Abstract:
An encoding and decoding method and apparatus support high speed multiplexing with a resolution of up to a single wavelength, in the speed range appropriate for photonic signal processing. The apparatus can support unbundling of sequential data patterns (such as packets etc.) down to an atomic level and rebundling for an arbitrary distribution pattern, with minimal overhead. A photonic encoder may encode at a rate governed by the cycle time of a photonic wave modulated in a domain selected from phase, frequency, amplitude, polarization, spread spectrum in time or frequency, or any combination thereof. Signals are split into daughter signals, having the exact wave form, absent amplitude equality, of the parent. Daughter signals may be serialized by a delay, spacing one daughter after another. A decoder splits the daughter signals into granddaughter signals and recombines them to provide noninterference, constructive interference, and destructive interference. By detection of photonic interference, a reconstituted output pulse may be formed, completely regenerating all information from the original signal. Overlaps between various daughter pulses may be used to provide amplitude increases in areas of interference having substantially reduced pulse durations, while lesser amplitudes remain elsewhere. Eventually, energy conservation may render lower amplitude regions below a noise level or cutoff level, thus concentrating the signal in a shorter duration, allowing more pulses to be encoded into a carrier, with less total energy density in the carrier for each pulse.

Description:
BACKGROUND  
         [0001]    1. The Field of the Invention  
           [0002]    This invention relates to computer systems and switches therefor and, more particularly, to novel systems and methods for switching and processing photonic information.  
           [0003]    2. Background  
           [0004]    Multiplexing is a method for transmitting multiple, distinct signals over a single physical carrier medium. Much of the protocol of computer hardware deals with the encoding and decoding of signals according to some time scheme for maintaining signal integrity and uniqueness from other signals. In conventional time-division types of multiplexing, signals are transmitted within specific time divisions or bit positions. In order to prevent individual bits from being transmitted at the same time, each is encoded into a signal and transmitted over the carrier medium at a specific time.  
           [0005]    As transmission rates increase, the individual time divisions available for each small quantity of information in a signal is reduced. However, with the advent of photonic processing, the transmission, encoding, and decoding of photonic signals taken from the electromagnetic spectrum, deserve further consideration. In conventional computer systems, as well as conventional telecommunications networks, the switching, routing, and transmission of signals throughout networks and between processors or processes is a major limiting factor in performance. Typically, transmissions of a signal require encoding of the signal in a carrier medium, according to a protocol or format.  
           [0006]    Thereafter, transmission occurs as a physical phenomenon in which light, or other electromagnetic radiation, electrical signals, mechanical transmissions, or the like are transferred between a source and a destination. At the destination, a decoder must then manipulate the physical response to the incoming signals, thus reconstructing original data encoded by the sender. Communications in general may include communications between individual machines. Machines may be network-aware, hardware of any variety, individual computers, individual components within computers, and the like.  
           [0007]    Thus, the issue of sending and receiving information or message traffic is of major consequence in virtually all aspects of industrial and commercial equipment and devices in the information age. Whether communications involve sending and receiving information between machines, or telecommunications of data signals, audio signals, voice, or the like over conventional telecommunications networks, the sending and receiving requirements of rapidly encoding and decoding are present.  
           [0008]    With the advent of photonic signals and photonic signal processing, new speed limits are being approached by transmission media. Moreover, origination of signals can now be executed literally at light speeds. Accordingly, what is needed is a system for multiplexing photonic signals over photonic carrier media in such a way as to maximize speed, while maintaining the integrity of information.  
           [0009]    Total throughput for any communication process will be limited by the slowest element or process occurring. Accordingly, faster computation in photonic computers and switches needs to be supported by appropriate communications within and between elements of such computers, as well as between computers, and between other telecommunications locations throughout the geography of the earth. Thus, multiplexing information over trunk carriers, with respect to collection of information and distribution of information on either end, will eventually become a limiting issue. Accordingly, what is needed is a method for multiplexing at maximum rates, while maintaining information integrity, to maximize throughput of systems.  
           [0010]    As advanced technologies are developed, the current infrastructure of the industrialized world will not disappear overnight. Accordingly, legacy equipment needs support. Moreover, in order to advance the deployment of high-speed technologies, it will be important for newer communication systems to interface with legacy equipment. Current telecommunication systems have been developed over decades. Accordingly, lines vary from wireless to copper wire, to fiber optics and the like.  
           [0011]    Likewise, the individual sending and receiving (transmitting/receiving) components operate at various speeds. In all communications, speed matching between components will be a major issue. With photonic communications, speeds are so drastically changed, that conventional protocols are inapplicable. Nevertheless, at some point, even a photonic network must communicate with an existing (legacy) piece of equipment. Matching signal formats, wave shapes, and the like, in order to be “understood” is necessary.  
           [0012]    What is needed is a method and apparatus for high speed multiplexing within the speed ranges appropriate for photonic signal processing. What is also needed is a convenient method and durable apparatus for interfacing between legacy equipment and photonic communications equipment. Also needed is an apparatus and method for encoding, routing, decoding, processing, manipulating, dividing, and recombining, complex wave forms containing information imbedded therein. Also needed is a method for literally assembling and disassembling complex structures of information in arbitrary manners in order to optimize the use of transmission resources.  
           [0013]    This process and apparatus should include unbundling sequential data patterns (such as packets etc.) and rebundling for an arbitrary distribution pattern, similar to the current package delivery system characterized by the Federal Express system. That is, in conventional telecommunications, packeting was more or less sacrosanct. Although packets were read, rewritten, repackaged, and so forth, they continued with their same internal structures. However, as the Federal Express system has proven with packaging, sometimes higher speeds can be achieved by centralizing or rerouting packaging and repackaging systems according to destination. Thus, some central, arbitrary hierarchical criteria whether organizational, geographical, priority, protocol, or other consistent thread of organization between certain information, may be useful as a mechanism for organizing transmission of information. Thus, according to the original receipt of information, information (data, communications, etc.) may need to be reorganized in order to provide faster and more effective or efficient delivery to destinations (receivers).  
           [0014]    One need in photonic telecommunications is the need for bundling and unbundling information (typically packets) for distribution. That is, like the Federal Express package delivery system, information must be gathered, sorted, and redistributed. In current systems, even those using fiberoptic cables, all bundling and unbundling is actually executed by devices operated electronically. Accordingly, the speed limits on transfer of information are imposed by the intermediary electronic equipment that must process signals for bundling and unbundling information.  
           [0015]    As photonic systems are developed, it would be an advance in the art to develop a fully photonic router that is capable of dynamic configuration for accomplishing both routing and provisioning functions in order to effectively and speedily distribute information. Creation of a fully photonic router, particularly one that could dynamically be reconfigured, would solve a major technological bottleneck that needs to be resolved before a fully photonic network can be implemented.  
           [0016]    Another need in photonic technology is the need for interfacing with legacy equipment. Interfacing with legacy equipment may be necessary where a legacy “last mile” of a network must interface with a fiber optic, photonic network. Moreover, as small fiber optic networks or photonic networks are installed, they must nevertheless interface with legacy interconnections existing in current infrastructure across the nation and the world. Thus, photonic systems must interface as interior elements of other networks, and must interface as terminal elements of other networks.  
           [0017]    Moreover, current technology in the electronic art provides for multiplexing. Both timedivision multiplexing and wave-division multiplexing may occur in legacy hardware. Bandwidth is increased by multiplexing, putting more signals over a single physical carrier in the same limited time and space. What is needed is additional bandwidth, and such bandwidth that will interface with legacy equipment. It would be an advance in the art if photonic multiplexers could be configured in series with conventional multiplexers, in order to increase bandwidth while interfacing with legacy equipment. Such massive increases in bandwidth can alleviate current limitations on information transfer.  
           [0018]    Thus, what is needed is a compound multiplexing system including serial multiplexing of both wave-division multiplexers and time-division multiplexers in series with new photonic multiplexers. Due to the “delay domain” provided by an apparatus and method in accordance with the invention, it is possible to provide a compound multiplexing system in which multiple photonic multiplexers are compounded with legacy multiplexers to send signals over a single physical carrier.  
           [0019]    Meanwhile, it would be a substantial advance in the art to compound multiple legacy multiplexers (time-division multiplexers, wave-division multiplexers, etc.) in a network served by photonic delayed-domain multiplexers feeding signals directly into the physical carrier medium.  
           [0020]    The high bandwidths available in photonic systems may be relied upon to carry highly secure communications. What is needed is an effective means for defeating interception or decoding of photonic information. It would be an advance in the art to provide a photonic communication network having multiple delay paths in order to provide security through integration of two separate routes. Accordingly, it would be an advance in the art if exact, coherent signals were required from two physically separate carrier medium passing through different geographical routes, in order to reconstitute secured information.  
           [0021]    It would be an advance in the art to add an additional level of multiplexing, by adding a delay-domain multiplexing capability to become compounded with NRZ equipment. Specifically, it would be an advance in the art to rely on delay-domain multiplex signals having the same frequency. It would be an advance in the art to be able to receive signals over multiple channels, from disparate sources, having the same, or substantially the same frequencies, and still be able to effectively multiplex those signals without cross talk.  
           [0022]    Much of legacy telecommunications equipment operates on a “non-return-to-zero” (NRZ) basis. That is, a signal is set, and remains at the set value until another signal unsets it or changes its value otherwise. Even fiber optic systems (photonic signal systems) may operate on an NRZ basis. It is important in developing a new technology, such as the photonic technology of the present invention, to continue providing support for legacy equipment. Since legacy equipment may include photonic (fiber optic, etc.) carriers and signals, including OC-48, OC-3, and other SONET systems, proper interfaces would be desirable when deploying new equipment in accordance with the invention.  
           [0023]    Thus, it would be an advance in the art to be able to create equipment in accordance with the invention that is effectively transparent to NRZ communications. Since conventional legacy equipment differentiates on a frequency basis, multiplexing is limited by the ability to distinguish individual frequencies.  
           [0024]    It would be an advance in the art to provide multiple channels associated with any individual time delay. Thus, when multiple sources, whether local or remote with respect to one another, are encoding in reliance on a particular time delay, it would be an advance in the art to provide channeling so that multiple messages or other information, having the same time-delay encoding, could nevertheless be managed simultaneously over the same carrier medium, by virtue of some multiplex method that allows coexistence through multiple channels. Alternatively, it would be an advance in the art to provide additional bandwidth by providing multiple channels at each individual delay-time, in order to increase input through a communication system. Moreover, it would be an advance in the art to be able to provide multiple channels through a single set of decoder hardware.  
           [0025]    No physical carrier medium can be fairly expected to carry an infinite amount of energy or to sustain an infinite energy density. Signals may be distorted as energy densities rise. Also, physical damage to carrier media and other components may occur due to excessive energy densities. As signals are multiplexed in greater number, the energy density in a carrier medium must be addressed.  
           [0026]    If not ameliorated, the energy density in the carrier medium may saturate the capacity of the medium, information may be lost by both the distortion of the encoded information in the medium, as well as through cross talk, and other sources of increased bit error rates. When electro-optics technology is relied upon at a receiving end of a transmission network, performance of the detection circuits and other devices may be adversely affected by the receipt of more energy than the saturation level will tolerate.  
           [0027]    What is needed is a method and apparatus for transmitting more information with less energy. Thus, when multiplexed together, multiple channels of signals or other multiplexed information streams need to have less energy so that more information can be passed over the same carrier medium.  
           [0028]    Specifically, it would be an advance in the art to provide a method and apparatus for narrowing the width (time) of a digital pulse in order to reduce the net energy in each pulse, while maintaining a minimum amount of energy to support the signal. What is needed is a reduced-energy transmission of information while maintaining a suitably high signal-to-noise ratio (SNR).  
           [0029]    In certain embodiments, encoding and decoding with high signal-to-noise ratios (SNRs) may be achieved with comparatively reduced energy.  
           [0030]    Electrical, electronic, and electro-optical devices have unacceptable speeds to handle photonic data transfer. Therefore, it would be a further advance in the art to provide a fully photonic method and apparatus for reducing pulse width, and thus concentrating information, while reducing energy levels, without sacrificing signal-to-noise ratio.  
         BRIEF SUMMARY AND OBJECTS OF THE INVENTION  
         [0031]    In view of the foregoing, it is a primary object of the present invention to provide a method and apparatus for encoding and decoding signals. Preferably, such an apparatus may include an ability to handle an input signal of arbitrary data rate.  
           [0032]    Consistent with the foregoing objects, and in accordance with the invention as embodied and broadly described herein, an apparatus and method are disclosed, in suitable detail to enable one of ordinary skill in the art to make and use the invention. In certain embodiments an apparatus and method in accordance with the present invention may include a photonic encoder connected to receive an input signal, and encode at a rate governed by the cycle time of a photonic wave. For example, in certain embodiments, encoding may occur within a single cycle of an electromagnetic wave, whether optical, microwave, or other spectrum. In alternative embodiments, a photonic decoder may connect to receive from an encoder an output signal over a transmission medium. A signal may be modulated in a domain selected from phase, spread spectrum over a time domain, over a frequency domain, over frequency itself, over amplitude, over polarization, or any combination of the foregoing.  
           [0033]    In certain embodiments, a modulated photonic source may encode signals by splitting a parent signal to provide subsequent daughter signals, having an exact wave form, absent amplitude equality, with the parent signal. Each of the daughter signals is coherent with each other, but the daughter signals may be serialized by a delay mechanism, spacing one daughter signal after another. In this way, the daughter signals are substantially identical to within the granularity of a single cycle of the photonic wave, except for amplitude. Input signals may actually be selected from digital pulses, analog signals, multi-level semaphore, multi-level logic signals, two-dimensional images, or the like.  
           [0034]    In certain embodiments, daughter signals may have a coherence characteristic rendering them unique as against all other transmitted signals. Amplitude equality is not required, since wave splitters or beam splitters typically provide some variation in the division of amplitude (energy content) of daughter signals.  
           [0035]    In selected embodiments, a coherence characteristic shared by daughter pulses may be selected from a coherence time less than a time duration of a wave form, a coherence time longer than the duration of a wave form, or a coherence time substantially equal to the duration of a corresponding wave form. Frequency content may be selected from a narrowband spectrum, broadband spectrum, or a combination thereof.  
           [0036]    Thus, first and second daughter signals, split from an original parent signal, may be characterized by a shared fingerprint comprising a combination of a coherence characteristic, and a frequency content. Meanwhile, a second daughter pulse or daughter signal (analog or digital, etc.) may be delayed with respect to a first daughter signal by a time delay characterized by a difference defined by traverse times between two paths. That is, a second daughter pulse may be delayed through a longer optical or photonic path, such as a changed index of refraction, a longer length or the like, in order to provide an offset in time between the two daughter signals.  
           [0037]    A combiner may be operably connected in order to recombine daughter signals, one now delayed, thus encoding the two signals for transmission to a destination. Delay mechanisms may include mirrors, prisms, holographic structures, fiber lengths, spatial paths, or the like calculated to provide a particular time delay. Meanwhile, image splitters or beam splitters may split the parent signal into daughter signals based on a domain selected from polarization, amplitude, wavefront, or the like. Moreover, multiple encoders and multiple decoders may be “ganged” in parallel or series.  
           [0038]    Similarly, at a receiving end of a communication, a decoder may also be formed using a splitter, for receiving daughter signals, and thus further splitting the daughter signals into granddaughter signals. Accordingly, a decoder combiner may then receive the granddaughter signals, recombining them in order to provide a combination of noninterference, constructive interference, and destructive interference. According to the photonic interference of the daughter signals, a reconstituted output pulse may be formed, completely regenerating all information from an original parent signal, which recombination can only be accomplished by exactly coherent waves such as the daughter signals and granddaughter signals, through photonic interference. Anything other than an identical (again absent amplitude) wave form will not produce the interference pattern required to give the reconstituted signal back.  
           [0039]    In certain embodiments, a method in accordance with the invention may include receiving first and second daughter pulses that arrive at a destination as a coherent set. The term “pulse” is for convenience and all that is stated regarding pulses applies to other signals as well. The daughter pulses may be characterized or created by receiving a pulse of energy, splitting a pulse into at least first and second daughter pulses, selecting a characteristic time, introducing a delay equal to the characteristic time, and transmitting the daughter pulses toward the destination as a coherent set. Thereafter, the method may include splitting from each daughter pulse, duplicate granddaughter pulses, delaying each according to the characteristic time and producing interference therebetween.  
           [0040]    The wave interference reflects the relative coherence between any set of first and second daughter pulses or granddaughter pulses. In certain embodiments, detection of the interference may rely on photonic detection, holographic detection, electronic detection, electro-optical detection, acoustic detection, or a combination thereof. Detection may also include detection of destructive interference, constructive interference, or differential therebetween.  
           [0041]    In certain embodiments, first and second daughter pulses may be received at a first destination as a coherent set and split into granddaughter pulses, one of which is then delayed with respect to a first granddaughter pulse by a time delay corresponding to an original encoding time delay. Recombining the granddaughter pulses produces wave interference, the output of which reflects the modulated information originally encoded. In certain embodiments, a plurality of photonic encoders and photonic decoders may be arranged in a configuration selected from parallel, series, or a combination thereof in order to provide effective multiplexing of signals. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0042]    The foregoing and other objects and features of the present invention will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Understanding that these drawings depict only typical embodiments of the invention and are, therefore, not to be considered limiting of its scope, the invention will be described with additional specificity and detail through use of the accompanying drawings in which:  
         [0043]    [0043]FIG. 1 is a schematic block diagram of a delay-domain multiplexing system in accordance with the invention;  
         [0044]    [0044]FIG. 2 is a schematic block diagram of a photonic network embodying an apparatus in accordance with FIG. 1;  
         [0045]    [0045]FIG. 3 is a schematic block diagram of a delay-domain multiplexer configured to receive a modulated signal containing information;  
         [0046]    [0046]FIG. 4 is a schematic block diagram of an encoder module, illustrating the details of internal operations thereof, in accordance with the apparatus of FIGS.  1 - 3 ;  
         [0047]    [0047]FIG. 5 is a schematic block diagram of an amplitude splitter for creating multiple daughter signals from an initial parent signal;  
         [0048]    [0048]FIG. 6 is a schematic block diagram of a polarization splitter configured to create daughter signals from an input parent signal;  
         [0049]    [0049]FIG. 7 is a schematic block diagram of a splitter illustrating the single-cycle character of the splitting function enabling single-cycle resolution of multiplexing information;  
         [0050]    [0050]FIG. 7A is a schematic block diagram of a splitter configured to process image signals and maintain spatial information in accordance with the invention;  
         [0051]    [0051]FIG. 8 is a schematic block diagram of one embodiment of a beam combiner in accordance with the invention;  
         [0052]    [0052]FIG. 9 is an alternative embodiment of a beam combiner in accordance with the invention;  
         [0053]    [0053]FIG. 10 is a schematic block diagram of an encoder module illustrating the operation of an assembly of beam splitters, mirrors, and other photonic elements;  
         [0054]    [0054]FIG. 11 is a schematic block diagram of a composite encoder module assembly configured to operate with multiple time delays, and thus provide multiple daughter signals from a single parent signal;  
         [0055]    [0055]FIG. 12 is a schematic block diagram of one embodiment of a decoder module, configured to provide coincidence detection in accordance with the invention;  
         [0056]    [0056]FIG. 13 is a schematic block diagram of one embodiment of a decoder module in accordance with the invention, and illustrating both holographic and beam splitter implementation;  
         [0057]    [0057]FIG. 14 is a timing diagram corresponding to the operation of the apparatus of FIG. 13;  
         [0058]    [0058]FIG. 15 is a timing diagram illustrating delay-domain multiplexing of multiple channels;  
         [0059]    FIGS.  16 - 17  are schematic block diagrams of alternative embodiments of a coincidence detection interferometer in accordance with the apparatus of FIG. 12 illustrating the single-cycle resolution of the interference process as used in an apparatus and method in accordance with the invention;  
         [0060]    [0060]FIG. 18 is a waveform diagram illustrating a delay-domain encoded analog signal;  
         [0061]    [0061]FIG. 19 is a timing diagram of one embodiment of a multi-level semaphore daughter signal set;  
         [0062]    [0062]FIG. 20 is a multi-domain signal, illustrating the characteristic fingerprint thereof, as an aggregate of time, frequency, and amplitude domains;  
         [0063]    [0063]FIG. 21 is a schematic block diagram of a decoder in accordance with the invention configured to process two-dimensional images;  
         [0064]    [0064]FIG. 22 is a schematic block diagram of a photonic processor for comparing differential outputs;  
         [0065]    [0065]FIG. 23A is a schematic block diagram of an alternative relying on an electronic processor for processing the complementary outputs of a decoder;  
         [0066]    [0066]FIG. 23B is a schematic diagram of a differential decoder as an alternative embodiment to the apparatus of FIGS. 22 and 23A, using noise cancellation to improve the signal-to-noise ratio;  
         [0067]    [0067]FIG. 24 is a schematic block diagram of a drop-rearrange-add apparatus for unbundling and rebundling multiplexed information;  
         [0068]    [0068]FIG. 25 is a schematic block diagram of compound-domain, broadcast multiplexing using a delay-domain multiplexor in accordance with the invention;  
         [0069]    [0069]FIG. 26 is schematic block diagram of an alternative embodiment of a compound multiplexing system in which the delay-domain multiplexing apparatus is interior in a network, with respect to conventional analog and other multiplexing apparatus;  
         [0070]    [0070]FIG. 27 is a schematic block diagram of one embodiment of a multiple-delay path for implementing encoding and decoding in accordance with the invention, and relying on integrated delay and delay correction;  
         [0071]    [0071]FIG. 28 is a schematic block diagram of one embodiment of an apparatus in accordance with the invention configured to process a non-return-to-zero (NRZ) signal transparently;  
         [0072]    [0072]FIG. 29 is a timing diagram corresponding to the apparatus of FIG. 28;  
         [0073]    [0073]FIG. 30 is a schematic block diagram of one embodiment of a phase-sequenced, dual-channel encoder;  
         [0074]    [0074]FIG. 31 is a schematic block diagram of a phase-sequence, dual-channel decoder;  
         [0075]    FIGS.  32 - 33  are timing diagrams for two channels of an apparatus in accordance with FIGS.  30 - 31 ;  
         [0076]    [0076]FIG. 34 is a schematic block diagram of one embodiment of a quadrature-encoding and decoding apparatus in accordance with the invention, incorporating two of each of the apparatus of FIGS.  30 - 31 ;  
         [0077]    [0077]FIG. 35 is a truth table for the decoder of FIG. 34;  
         [0078]    [0078]FIG. 36 is timing diagram corresponding to the apparatus of FIG. 34;  
         [0079]    [0079]FIGS. 37A and 37B are schematic diagrams of a polarization beam splitter, illustrating the relationship between the polarization components, with respect to an apparatus in accordance with the invention;  
         [0080]    [0080]FIG. 38 is a schematic block diagram of a double encoder relying on polarization sequencing to differentiate multiple channels sharing a single time delay between encoded daughter signals;  
         [0081]    [0081]FIG. 39 is a schematic block diagram of a double decoder relying on polarization sequencing to differentiate two channels sharing a single time delay, in accordance with the apparatus of FIG. 38;  
         [0082]    FIGS.  40 - 41  are timing diagrams corresponding to two channels of an apparatus in accordance with FIG. 39;  
         [0083]    [0083]FIG. 42 is a schematic block diagram of a pulse concentrator in accordance with the invention;  
         [0084]    [0084]FIG. 43 is a timing diagram illustrating the signal processing, and resulting concentration of pulses, of the apparatus of FIG. 42;  
         [0085]    [0085]FIG. 44 is a schematic block diagram of an apparatus in accordance with the invention provided with a burst generator and subsequent processing of a signal generated thereby;  
         [0086]    FIGS.  45 - 46  are schematic block diagrams of alternative embodiments of a burst generator in accordance with FIG. 44;  
         [0087]    [0087]FIG. 47 is a timing diagram of a burst generator in accordance with FIGS.  44 - 46 ;  
         [0088]    [0088]FIG. 48 is a schematic block diagram of a compound modulation apparatus in series with a delay-domain multiplexing system;  
         [0089]    [0089]FIG. 49 is a schematic block diagram of one embodiment of a pre-conditioning modulator corresponding to the apparatus of FIG. 48; and  
         [0090]    [0090]FIG. 50 is a chart reflecting one embodiment of a frequency shift between a delayed daughter signal associated with a first daughter pair and direct daughter signal associated with a subsequent daughter pair. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0091]    It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the system and method of the present invention, as represented in FIGS. 1 through 23, is not intended to limit the scope of the invention. The scope of the invention is as broad as claimed herein. The illustrations are merely representative of certain, presently preferred embodiments of the invention. Those presently preferred embodiments of the invention will be best understood by reference to the drawings, wherein like parts are designated by like numerals throughout.  
         [0092]    Those of ordinary skill in the art will, of course, appreciate that various modifications to the details of the Figures may easily be made without departing from the essential characteristics of the invention. Thus, the following description of the Figures is intended only by way of example, and simply illustrates certain presently preferred embodiments consistent with the invention as claimed.  
         [0093]    Referring to FIG. 1, an apparatus  10  for communications, over an all-photonic or fully-photonic transmission system may include an encoder  12  for encoding signals at photonic speeds. By photonic is meant all electromagnetic radiation in which communications may be embodied, regardless of frequency. Thus, photonic frequencies include microwave, radio waves, optical waves, and the like. The encoder  12  may transmit signals embodying information to a decoder  14  at a receiving end of a transmission system.  
         [0094]    The transmission medium  16  connecting the encoder  12  to the decoder  14  may be any medium suitable for carrying a photonic transmission in a wavelength selected. Typical transmission media may include fiberoptic fibers, fiber bundles, (particularly coherent fiber bundles in which positions of fibers in the bundle are maintained with respect to one another in order to transmit “pixel-light” elements of images) two-dimensional arrays of signals, and the like, while maintaining any spatial distribution or modulation imposed on the signals.  
         [0095]    Metal structures of various types may be used as wave guides in various electromagnetic frequency ranges. For example, microwave transmissions may include gold, copper, aluminum, brass, silver, or other wave guides shaped as wires, tubes, and the like, in order to transmit photonic signals. In general, the purpose of any communication network, such as the apparatus  10 , is delivery to a destination  18  of information (typically embodied in some type of a signal to be decoded) from a source  20  or a data stream  20 .  
         [0096]    In one presently preferred embodiment, the delivery of data  20  at an origin may be committed to the transmission process at an arbitrary rate or speed. Accordingly, in certain embodiments, an encoder  12  may operate at such speeds as to accommodate any arbitrary speed of the originating data  20 . In the limit, the encoder  12  and corresponding decoder  14  may operate at speeds suitable for handling data up to the cycle time of an individual wave of electromagnetic energy. This means that an individual bit, in the limit, may be represented as one wavelength of a photonic carrier modulated to embody the transmitted information.  
         [0097]    Information is embodied in signals. Signals have some minimum size or maximum level of resolution. That is, information ultimately must be recognizable in order to be encoded and decoded.  
         [0098]    Typically, in digital data, a bit is a single piece of information, a one or a zero value. Nevertheless, in an analog signal, the same principle exists. That is, some minimum level of distinguishable modulation must be interpreted as information. Often in a process of communication or competition, data is referred to as data at an “atomic” level. An atomic level of data is the smallest size that any process can recognize as an individual, processible unit.  
         [0099]    In digital data, a bit is the smallest atomic level of data. In certain embodiments, binary data may actually be digital or analog. Thus, referring to ones and zeros as digital or binary, should not be interpreted to restrict in any way an apparatus and method in accordance with the invention. Thus, in a binary sense, data can be modularized in accordance with the invention down to an atomic level corresponding to a single bit of data. Meanwhile, that bit can be modularized or embodied down to a single wavelength of a carrier.  
         [0100]    One may think of an apparatus and method in accordance with the invention as representing a time-division, multiplexer. That is, a multiplexer is an apparatus for combining information streams from various sources, and transmitting those streams, in a pseudo-simultaneous manner, by dividing portions of the information of each stream and interleaving them in a time-division multiplexed fashion. Thus, a single carrier may simultaneously carry streams from multiple sources, interleaved at some division level.  
         [0101]    Referring to FIG. 2, data  22  from a variety of sources, may be embodied in signals  24  (for example, signals  24   a ,  24   b ,  24   c ). Each of the signals  24 , embodying information  22  or data  22  must then be encoded in some type of encoder  12  in a fashion that may be interpreted later by a decoder  14  at a destination.  
         [0102]    Broadcast routing refers to the ability of a system  10  to combine the information  22  from disparate encoders  12  and even combine it through various junctions  28  (for example, the junctions  28   a ,  28   b ) at disparate times and places. Thus, by combining streams of information at various junctions  28 , a single line  30  may become a trunk carrying multiplexed information from widely distributed times and places, as it is transmitted to widely disparate destinations.  
         [0103]    Similarly, junctions  32  may be responsible to subdivide, physically, the energy embodied in a multiplexed signal, in order to deliver to ultimate decoders  14  at disparate destinations the information embodied in the original data  22 . At a destination, a decoder  14  corresponding to an encoder  12 , may decode signals for additional processing by a post processor  36 , ultimately responsible to deliver data  38  reconstituting the original data  22 .  
         [0104]    In certain embodiments of an apparatus and method in accordance with the invention, the lines  37  may have post processing. The signal  38  that is a virtually identical representation of the original signal  24 . Accordingly, the apparatus  10  or network  10  may actually become a virtual fiber, reconstituting signals  38  identical to signals  24 , regardless of intervening media, formatting, other multiplexed signals, or the like. Thus, a multiplexed signal, may be regarded as if it had been sent over a dedicated line, due to proper encoding and decoding.  
         [0105]    Referring to FIG. 3, a differential-delay multiplexer  10  may include a signal  22  received through a modulator  40  outputting a modulated signal  42 . The modulated signal  42  is received by a photonic source  44  and converted into a photonic signal  46 . The photonic signal  46  may be regarded as a parent signal  46 , such as a signal  24  of FIG. 2, which will eventually result in the daughter signals  48  output as a result of the operation of the encoder  50  (e.g. an encoder  12 ) in accordance with the invention.  
         [0106]    One principal mechanism used by the encoder  50  is imposition of a time delay  49  between daughter signals  48  that each embody all of the wave characteristics of the signal  46 , absent amplitude, since amplitude can vary from exact equality in a splitting operation. The responsibility of the encoder module  50  is to prepare a signal  48  suitable for transmission to an ultimate destination. In an apparatus and method in accordance with the invention, the encoder module  50  creates time-delayed signals  48 , thus creating a differential delay multiplexing encoder for creating a plurality of signals  48  of exact coherence, and virtually identical wave form absent amplitude.  
         [0107]    Referring to FIG. 4, an encoder module  50  may include a splitter  52  for producing duplicate signals  48   a ,  48   b  from a parent signal  46 . In one presently preferred embodiment, a time delay apparatus  54  may provide a differential delay  49  between the signals (e.g. pulses)  48   a ,  48   b . Thus, the path  55   a  may be regarded as a direct path, while the path  55   b  may be regarded as a delay path. The delay may be incorporated by any suitable mechanism such as a change in the indices of refraction between two materials or between portions of a single material, and additional distance in space or through a particular device, transmission medium, or the like. In certain embodiments, the time delay mechanism  54  may be adjustable. Nevertheless, in other embodiments, a fixed time delay  49  from the apparatus  54  may be adequate.  
         [0108]    In the embodiment of FIG. 4, a combiner  56  effectively multiplexes the signals  48   a ,  48   b  into the encoder output  48  illustrated. Thus, each of the pulses or signals  48   a ,  48   b , whether analog or digital, is separated by a time delay  49  between corresponding locations in the wave form.  
         [0109]    Referring to FIG. 5, a parent signal  46  may provide an input to a splitter  52  of various constructions. In the illustrated embodiment, the splitter  52  divides the parent signal  46  into daughter signals  48  relying on an amplitude splitter. Thus, the intensities or energy levels of the daughter signals  48  may be approximately halved with respect to that of the parent signal  46 .  
         [0110]    Nevertheless, all other aspects of the wave form of the daughter signals  48  can be expected to be coherent with each other, and identical to each other and the parent signal  46 , except for amplitude. That is, since the amplitude has been split, the total energy of each daughter signal  48  must be different from that of the parent  46 , and typically will be approximately half thereof. Nevertheless, the signals  48  are “complementary” in that the sum of their energies substantially equals the sum of the energy of the parent signal, but energies need not be equal to each other.  
         [0111]    Referring to FIG. 6, an input signal  46 , or parent signal  46 , may also be split by a polarization splitter  52 . In order to rely on a polarization splitter  52 , a polarization stabilizer  58  may be required. One reason for the polarization stabilizer  58  is that the daughter pulses  48  have different polarizations. Rather than dividing on amplitude, the daughter signals  48  are divided on polarization. That is, each may typically be a single component, orthogonal to each other, of the original parent signal  46 . Accordingly, if the polarization stabilizer  58  is not used, then care must be taken to assure that both orthogonal components and therefore both daughter signals  48 , are present.  
         [0112]    Otherwise, the polarization splitter  52  may effectively filter an entire component, rendering no daughter signal  48  in one of the channels. Commonly, when speaking of polarization, those in the art refer to a horizontal component and vertical component. These components are merely reflective of the orthogonal relationship between the two components, and do not necessarily refer to any absolute frame of reference.  
         [0113]    Referring to FIG. 7, one embodiment of a splitter, of which both amplitude and polarization splitters are available configurations, may rely on an input wave  62  having a plane wavefront  68 . Typically, a collimating apparatus may provide a plane wavefront  68  in a wave  62  input into a splitter  60 . Typically, a splitter  60  may be one of several types, including cubes, Wallaston prisms, Thompson prisms, calcite and other birefringent materials, and the like. In the embodiment of FIG. 7, the splitter  60  is of a cube type in which the splitter  60  includes a solid cube of optically or otherwise photonically transparent material. Along the surface  61  is a material that is partially transparent, even selectively transparent, depending upon the splitter type.  
         [0114]    For example, in a polarization splitter  60 , the surface  61  is polarization selective so as to transmit a wave  64 , representing part of the energy of the wave  62 , and to reflect a wave  66  containing the remainder of the energy of the input wave  62 . An amplitude beam splitter  60  transmits a portion of the energy of the input wave  62  into a transmitted portion  64 , reflecting the remainder in a reflected beam  66 .  
         [0115]    A significant feature of the beam splitter  60  is that the plane wavefront  68  remains a plane wavefront in the outputs  64 ,  66  because each individual wave  68  transmits or reflects on a cycle-for-cycle basis at the splitting surface  61 , without amalgamation, confusion, or loss of any of the embodied information.  
         [0116]    In one presently preferred embodiment, the surface precision of the surface  61  is sufficient to prevent any amalgamation of information between individual cycles (wave  68 ) with respect to either preceding or subsequent waves in the input stream  62 . Although a beam having a spherical wavefront could be substituted for the input bream  62 , and a spherical beam splitter surface could be substituted for the planar beam splitter surface  60 , the architecture of FIG. 7 is simple, reliable, and capable of effecting the splitting process while maintaining necessary coherent interaction on a wave-by-wave basis.  
         [0117]    Geometrically, it is clear that the surface  61  turns each wave  68  sequentially as it “walks down” the surface  61 , providing an exactly reconstructed plane wavefront  70  on reflection, or passing the wave  72 , each in turn walking down the surface  61 , and providing the output  64 . Accordingly, coherence and all other features of the waves  64 , 66  may be effectively preserved, with the exception of the feature that has been split off (amplitude, polarization state, etc.).  
         [0118]    Referring to FIG. 7A, one embodiment of a splitter  60  may receive input signals  63  configured to embody information contained in the spatial distribution of the signal  63 . Thus, energy may be distributed over an area, rather than just serially or sequentially in a single dimension as in the wave  62  of FIG. 7. Both temporally modulated and spatially modulated inputs or images  63  are available. Accordingly, when the splitter  60  passes a portion  65  or a daughter signal  65 , and reflects, a daughter signal  67 , each of the daughter signals  65 ,  67  contains a portion of the energy of the original signal  63 , but all of the spatially modulated and temporally-modulated information originally included in the input signal  63 . Of course, the daughter signals  65 ,  67  correspond exactly to daughter signals  48  of FIGS.  3 - 4 . Accordingly, each of the images  65 ,  67  may be encoded precisely as illustrated in the apparatus and method of FIGS.  3 - 4 . Therefore, as in all of the apparatus and methods of FIGS.  1 - 7 , the transmission medium  16  into which each of the signals  65 ,  67  is transmitted may operate at photonic transmission speeds and may be selected from any suitable medium, from free space interconnections, and any other coherence-maintaining image conductor, such as coherent fiber bundles, optical solids, or other fully-photonic, coherent image transmission systems.  
         [0119]    It should be remembered that each of the signals  63 ,  65 ,  67  may be modulated in time as an analog, digital, or sequential image, whether recognizable by human interaction or by other machine recognizable means. An additional benefit of the apparatus of FIG. 7A is that beam quality may be maintained. Specifically, beams typically embody a power distribution across their cross section. The variation may be referred to as a profile. Since the profile may vary in amplitude across an image, maintenance of beam quality assures full retrieval of the entire image profile upon decoding. Accordingly, the apparatus of FIG. 7A supports free space interconnection of multiple modules in any conceivable network configuration. Each individual component will be “transparent” to the transmitted images  63 ,  65 ,  67 .  
         [0120]    Referring to FIGS.  8 - 9 , a combiner  56  (see FIG. 4) may be embodied in one of several architectures. For example, in the illustration of FIG. 8, a mirror  76  or reflector  76  may reflect an input beam  55   b  to a path  77  or signal  77  reflected through a lens  78 . Meanwhile, a beam  55   a  (For example, the undelayed signal  55   a ) passes by the reflector  76 , and also passes through the lens  78 . Accordingly, the lens  78  combines the beams  55   a ,  55   b  (reflected  77 ) toward an aperture  80  for receiving the combined beam  84  to be conducted by a fiber  82  or other conducting mechanism. Thus, the lens  78  focuses the beams  55   a ,  55   b  such that the aperture  80  effectively multiplexes both signals  55   a ,  55   b  for transmission through the fiber  82 .  
         [0121]    Referring to FIG. 9, the input beam  55   a  may pass through a beam splitter type of combiner  56 , which may be of an amplitude or polarization type. Similarly, the input beam  55   b  (typically the delayed daughter pulse  55   b ) reflects from splitter  56 . Thus, the combined beam  84  represents the contribution of the reflected beam  55   b , and the transferred beam  55   a  passing through the combiner  56 .  
         [0122]    Referring to FIG. 10, an encoder module  50  may optionally receive a signal  46  through a polarization-orienting device  86 . The polarization-orienting device  86  is optional, and depends on the type of input signal  46 , relative to the operational characteristic of the encoder  50 . For example, polarization beam splitting requires that the signal  46 , or the signal  46 , after processing by an orienting device  86 , be properly prepared to operate in conjunction with the beam splitter  52  and the combiner  56 .  
         [0123]    In the embodiment of FIG. 10, a signal  46  is transmitted to a beam splitter  52  that passes a direct signal  55   a  to a combiner  56 , and a delayed signal  55   b  off mirrors  87 ,  88 , embodying a delay path. Accordingly, the distance involved in passing over the mirrors  87 ,  88 , being indirect, results in a time delay  49  between each of the daughter pulses  48   a ,  48   b  resulting as outputs.  
         [0124]    Meanwhile, the combiner  56  may be of one of several different available types. In one embodiment, the combiner  56  may be a hologram  90 . The hologram  90  receives the direct  55   a  and delayed  55   b  signals at a surface  91  configured for the purpose of combining the signals  55  into an output  48 .  
         [0125]    Similarly, a mirror-type or beam-splitter-type combiner  56  may involve a partially-transmitting/partially-reflecting mirror  92  having a combining surface  93  for combining the direct  55   a  and delayed signal  55   b  into an output signal  48 . Alternative embodiments of a combiner  56  may involve other phenomenon. For example, a combiner  56  may be selected from a fiber combiner, a collection of optical elements, various types of holograms, a non-focusing energy concentrator, partially reflecting mirrors, non-linear optical elements, a polarization combiner, or the like.  
         [0126]    Moreover, the delayed signal  55   b  may be delayed by one of several phenomena. Traversing distance as illustrated in FIG. 10, is one simple embodiment that operates well in free space. Alternatively, time delays may be introduced into the signal  55   b , or to delay the signal  55   b  from the signal  55   a , by the addition of a wave guide, films, free space and distance, optical fibers, optical elements of differing indices of refraction, or the like. Moreover, differing types of delays may be introduced in different portions of encoders and decoders for accomplishing the same purpose.  
         [0127]    For example, an encoder may use one mechanism for time delay, while a decoder may use a different mechanism to impose the same time delay in order to match the required time differential  49  between corresponding portions of daughter pulses  48   a ,  48   b  Moreover, in certain embodiments, an adjustable delay mechanism  54  may be used for the time delay  49 . An adjustable mechanism  54  may actually be programmed to track or hunt for a particular time delay, or to move in accordance with a pre-programmed algorithm for determining time delay.  
         [0128]    Thus, a certain amount of additional encoding, cryptography, or adjustment may be provided by an adjustable mechanism  54 . Moreover, a time delay  49  may be produced in an encoder  12  or decoder  14 , by a fixed delay mechanism  54 , while the time delay in the other may be provided by an adjustable time delay mechanism  54 . Thus, the transmission and receiving processes may be tuned to one another, much as a radio may be tuned up and down the available band to select a particular channel or a particular frequency. Meanwhile, adjustability may actually be done in a “digital fashion” or modular fashion, by which specific, fixed, time delays  49  may be introduced by selection and insertion, followed by removal in favor of another time delay  49 . Thus, as snap-in modules, time delay mechanism  54  may be replaced in a rapid, interchangeable fashion.  
         [0129]    An individual person is typically not capable of adjusting high-speed devices at appropriate rates. Accordingly, a computerized control mechanism may be used to adjust a time delay  49 . Similarly, changing channels, or tuning, as well as insertion and replacement, followed by further replacements of time delay mechanism  54  may be accomplished by a computerized control mechanism, servos, or the like.  
         [0130]    Referring to FIG. 11, an encoder  50  in accordance with the invention may rely on splitting a parent signal  24  in one or more splitters  52 , in order to provide a series of daughter pulses  48 . Each of the daughter pulses  48   a ,  48   b ,  48   c ,  48   d , and so forth, may have a separate, corresponding time delay  49   a ,  49   b ,  49   c ,  49   d , etc. In certain embodiments, alternative splitters  94   a  may continue to subdivide or split the energy of the original input signal  24 , as received by the splitter  52 . Splitters  94  may be arranged in a series, parallel, and in a variety of configurations in order to provide additional daughter pulses  48 .  
         [0131]    In one embodiment, individual time delays  49  may be created by time delay mechanisms  54  associated with each individual signal  55  (e.g.  55   a ,  55   b ,  55   c ,  55   d ,  55 E e  etc.) in order to provide improved signal processing. For example, some of the purposes for providing more than two daughter signals  48  include an improved signal-to-noise ratio in certain networks, and inclusion of additional addressing information in certain types of networks. Thus, each of the signals  48  may contribute to an improved signal-to-noise ratio, or may include additional addressing information.  
         [0132]    For example, not only can additional addresses or locations be identified for additional daughter signals  48 , but coding may actually be embodied in the actual signal profile. This profile may be used, for example, to encode additional addressing information that may be interpreted by a receiving network at some point. Particularly in complex combinations of the features of the present invention, in sophisticated networks, addressing information may be so encoded in order to provide additional addressability, without requiring additional bandwidth. An improved signal-to 5  noise ratio may not be evident in the daughter pulses  48  themselves, immediately. However, in keeping with the reconstitution of output signals  38  as a result of the decoder  14 , individual signals  48  are nonlinearly combined, thus, providing greater contrast against a baseline of noncoherent line noise or other signals.  
         [0133]    Referring to FIG. 12, a decoder  14  may receive a signal  48  through an optional filter  96 . Although the filter  96  is not required, filter technology is available to filter out unwanted noise, or to allow the use of an apparatus in accordance with the invention in a wave-division-multiplexed system. Thus, a filter  96  may permit filtering of inappropriate signal content, particularly in an interface with legacy networks.  
         [0134]    In one embodiment of the decoder  14 , a splitter  98  may split the incoming daughter signals  48  received from the encoder  50 . The splitter  98  may be selected from any of the types discussed above with respect to the encoder module  12 . Accordingly, the splitter  98  should typically correspond in operation to the functional operation of the beam splitter  52  of the encoder module  50 . Similarly, a splitter  98  produces or transmits a direct signal  102  and a delayed signal  104 . The delayed signal  104  may be delayed for an appropriate time delay  49  corresponding to the original delay  49  by the encoder  50 . Nevertheless, if a decoder  14  is to be operated at a resolution less than the cycle-for-cycle precision possible, then the time delay  49  between the signals  102  and  104  must be substantially the same as the encoder time delay  49 , but need not be exact. Thus, the time delay device  106  may be constructed and operated in accordance with the principles discussed for the time delay device  54 .  
         [0135]    Each of the signals  102 ,  104  may be thought of as a granddaughter signal, being a daughter signal  102 ,  104  of the original daughter signals  48 . A coincidence detection interferometer  100  has responsibility for comparing the granddaughter signals  102 ,  104  with one another. Accordingly, the interferometer  100  provides complementary outputs  108 ,  110 . One of the complementary outputs  108 ,  110  will result from constructive interference between the granddaughter signals  102 ,  104 . The other of the complementary outputs  110 ,  108  respectively, will result from destructive interference between the granddaughter signals  102 ,  104 . In one presently preferred embodiment, a device  18  or post processing device  18  may rely on photonic or electronic mechanisms in order to process the complementary outputs  108 ,  110 . In a photonic device  18 , the signals  108 ,  110  may simply be passed through or directed for further processing. Similarly, an electronic detector  18  may reduce the photonic signals  108 ,  110  to electronic signals, for incorporation into controls for other electronic devices. Also, if the signal  38  is photonic, after post processing in the device  18 , then it may be used directly as a signal, or as a control for other photonically controlled devices. All of the components necessary to construct a photonic post processor  18 , may be derived from basic photonic transistor technology and other associated logical photonic components.  
         [0136]    Referring to FIG. 13, a decoder module  14  may receive a signal  48 , constituting the relatively delayed daughter signals  48  from the encoder  12 , and specifically, from the encoder module  50 . The embodiment of FIG. 13, illustrates one method, relying on free-space delay techniques, although all delay techniques are available. Similarly, the coincidence detection interferometer  100  is illustrated in two alternative embodiments, although all of the polarization beam splitter, non-linear optical elements, partially reflecting mirrors, holograms, a collection of optical elements, and a fiber combiner are all possible elements to be relied upon by the interferometer  100 .  
         [0137]    The signal  48  may be split by a beam splitter  98  into granddaughter pulses  102 ,  104 . Accordingly, the mirrors  114 ,  116  may be fixed or adjustable mechanisms for adjusting the time delay  49 , and thus tuning the decoder module  14 . Meanwhile, the interferometer  100  receives the direct signal  102 , and the delayed signal  104  (granddaughter signals  102 ,  104 ). The delay device  120  may include adjustment in a direction  118 , of both mirrors  114 ,  116 . Alternatively, the delay adjustment mechanisms discussed heretofore may also be relied upon as delay devices  120 .  
         [0138]    The interferometer  100  of FIG. 13, includes a hologram  122  operating as an interferometer receiving a direct signal  102 , and delayed signal  104 . The hologram  122  is configured to output complementary signals  108 ,  110 , as described above. Similarly, in an alternative embodiment, a partially-reflecting mirror, or polarization beam splitter, may serve as the beam splitter  124 . The direct signal  102  and delayed signal  104  may input into the beam splitter  124  in order to provide the complementary outputs  108 ,  110 .  
         [0139]    Referring to FIG. 14, daughter signals  48   a ,  48   b  are displaced from one another by a time delay  49 . Each of the daughter pulses  48   a ,  48   b  is transmitted from the encoder  12 , to arrive, eventually, at the decoder  14 . In the decoder  14 , the daughter pulses  48   a ,  48   b  are further split into granddaughter pulses  126 ,  128 . A direct signal  102  includes one set of signals  126 ,  128 . Meanwhile, a delayed signal  104  includes a later set of signals  126 ,  128 . Inasmuch as the granddaughter pulses  126 ,  128  are coherent, superposition will result in constructive or destructive interference.  
         [0140]    In general, the signal  108  may result in an output condition that is either constructive or destructive. Similarly, depending upon the phase relationship between the granddaughter signals  126 ,  128 , the signal  110  may result in a destructive or constructive interference signal. The superposition signal  129  results from superimposing the signal  102  and the signal  104 . The result is a central constructive interference region  130 . The constructive interference region  130  provides an amplitude identifying the constructive interference resulting from the superposition of the granddaughter signal  126 , from the signal  104 , and the granddaughter signal  128 , from the signal  102 .  
         [0141]    Meanwhile, the superposition signal  131  results from destructive interference between the granddaughter signal  126 , from the signal  104 , and the granddaughter signal  128 , from the signal  102 . A non interference region  132  exists due to the presence of a granddaughter signal  126 , which provides no interference with another signal, but has an amplitude that is nonzero.  
         [0142]    Similarly, following the constructive interference signal  130 , the superposition signal  129  includes another non interference region  134 . In this case, the granddaughter signal  128  from the signal  104  has no corresponding, coherent signal with which to create interference, but has a nonzero amplitude. The superimposed signal  129  or superposition signal  129  is one embodiment of a complementary output  108 ,  110 , as appropriate.  
         [0143]    Meanwhile, between the noninterference regions  132 ,  134  of the superposition signal  131  (an alternative candidate for either one of the complementary outputs  108 ,  110 ), a destructive interference region  136  provides a zero-amplitude signal. The zero value in amplitude results from destructive interference between the granddaughter signal  126  out of the delayed signal  104 , and the granddaughter signal  128  out of the direct signal  102 .  
         [0144]    The result of the superposition signal  129  is a reconstituted output  38  in the case of constructive interference. In the case of destructive interference, a reconstituted output  38  may be a zero signal. Nevertheless, in one embodiment of the apparatus of FIGS.  12 - 13 , the decoder  14  produces constructive interference from one of the complementary outputs  108 ,  110 , and destructive interference in the other complementary output  110 ,  108 , respectively.  
         [0145]    Whether or not a complementary output  108 ,  110  is constructive or destructive depends on the phase relationship between the direct signal  102  and the delayed signal  104 . An adjustable time  1  e delay device  106  may be responsible for the adjustment  118  of the mirrors  114 ,  116  in the apparatus of FIGS.  12 - 13 . Thus, phase can be maintained in order to assure constructive or destructive interference in a complementary output  108 ,  110 .  
         [0146]    In one embodiment, phase may be maintained in order that one of the complementary outputs  108 ,  110  always represents (e.g. becomes) a constructive interference channel, while the other  110 ,  108  represents (e.g. becomes) a destructive interference channel. In other embodiments, phase may be manipulated in order to provide multiple channels of outputs, in which each of the complementary outputs  108 ,  110  may selectively provide destructive interference or constructive interference outputs.  
         [0147]    Referring to FIG. 15, different channels  24  may contain data derived from different parent signals. As illustrated in FIG. 2, parent signals  24  may come from various locations, and may be networked together in any geometric configuration over virtually any supportable geography. Broadcast routing may be supported by a multiplexing process in which individual daughter pulses  138   a ,  138   b , for example, on an individual channel  24   a , are separated by a time differential  148   a . (Any signal and waveform can be substituted for the work pulse herein) Other daughter pulses  140   a ,  140   b  on a different channel  24   b  may be separated by another arbitrary time differential  148   b . The system requirements to prevent unintended interference, to maintain channel isolation, and to prevent cross-talk in a broadcast routing environment are determined by the time differentials  148   a ,  148   b ,  148   c ,  148   d ,  148   e , the operating frequencies, and the coherence times of the respective photonic sources generating the parent signals  24   a ,  24   b ,  24   c . In other words, time differences and relative signal coherence properties govern system operations. By selecting unique time differentials  148 , and photonic sources having coherence times shorter than the shorter of the two: the shortest time differential and the shortest time difference between time differentials, unintended interference is precluded and channel isolation is guaranteed.  
         [0148]    Nevertheless, if the “unrelated” daughter pulses  138 ,  140 ,  142 ,  144 ,  146  are in danger of being coherent with each other, then the time differentials  148  may be adjusted accordingly, in order to multiplex overtime. Alternatively, photonic sources having shorter coherence times or different frequencies of operation may be employed.  
         [0149]    Coherence length is not an absolute measurement for any system. Accordingly, each set of daughter signals  138 - 146  should have different time differentials  148 , frequencies, or the like, in order to distinguish them. Nevertheless, the time differential  148  between any pair of daughter signals  138 - 146  is typically selected to be unique. Accordingly, in order to produce the constructive or destructive interference of FIG. 14, a set of daughter signals,  140   a ,  140   b , for example, has a time differential  148   b  known by the encoder  12  and the decoder  14 . Thus, unless a granddaughter signal  126 ,  128  arrives at the coincidence detection interferometer  100  both coherent and delayed by the proper time, proper constructive or destructive interference will not occur.  
         [0150]    In order to eliminate any potential interference between channels  24 , short coherent lengths are suitable. This will maximize the bandwidth, or number of channels  24 , that may be carried over an individual carrier. Typically, the coherence time (length) of a particular signal should be less than the shortest time differential  148  associated therewith. In certain embodiments, the coherence time (length) may be less than the longest time differential  148 , or less than the shortest time differential  148 . In certain preferred embodiments, the coherence time (length) may be less than the shortest time differential  148 , and shorter than the shortest signal pulse, or equivalent  138 ,  146 .  
         [0151]    It should be remembered that signals  138 - 146  need not be digital pulses. Nevertheless, in certain embodiments, the signals  138 - 146  may be pulses. In any event, a coherence length less than a signal length of interest may advantageously provide additional assurance against crosstalk between channels  24 .  
         [0152]    One advantage of an apparatus and method in accordance with the invention is that comparatively short coherence lengths may be used to advantage, whereas in conventional signal processing, a long coherence length is desired. Moreover, it is appropriate to speak of pulse width and pulse length, although signals  138 - 146  need not be pulses.  
         [0153]    Referring to FIGS.  16 - 17 , a beam splitter  122 ,  124  may be configured in one of several suitable configurations in accordance with the present invention. In the embodiment of FIG. 16, a beam splitter  124  may have an interferometric surface  150 . In accordance with the invention, an incoming signal  102 , a photonic signal input as a plane wave, enters the beam splitter  124 , eventually encountering the surface  150 . The incoming beam  102  walks up the surface  150 , encountering and creating interference with the delayed input beam  104 .  
         [0154]    As illustrated, the beams  102  (direct input) and  104  (delayed input) interact on a cycle-for-cycle basis. The complementary outputs  108 ,  110  result. In the event of constructive interference, and in accordance with an appropriate phase of each signal  102 ,  104 , relative to each other, a constructive interference wave may proceed out as either the complementary output  108 , or the complementary output  110 .  
         [0155]    Similarly, opposite to the output path  108 ,  110  of a constructive interference wave, a destructive interference wave may propagate out the opposite complementary output  110 ,  108 . Thus, by selective management of the relative phase of the input waves  102 ,  104 , two channels  108 ,  110  for constructive interference may be provided. A destructive interference condition may propagated in an opposite condition.  
         [0156]    Other shapes for the surface  150  are tractable. However, a plane surface  150  is a suitable and simple construction for ease of manufacture by several methods. It is advantageous to have plane-wave beams  102 ,  104  correspond to the planar surface  150 . Other wavefront surface geometries with corresponding splitter surface geometries  150  are possible. For example, spherical beams  102 ,  104 , with a spherical splitter surface  150  could be used.  
         [0157]    Referring to FIG. 17, the surface  150  may be a developed emulsion formed as part of a hologram  122 . As a practical matter, the surface  150  may be manufactured on a substrate that participates, or does not participate, in wave mechanics of the apparatus  100 . In one presently preferred embodiment, a direct input  102  as a plane wave  102  and a delayed input  104  as a plane wave  104  may walk up the surface  150 , interfering on a cycle-by-cycle basis. Depending upon the relative phase of the input beams  102 ,  104 , a constructive interference output beam may be produced as one of the complementary outputs  108 ,  110 . A destructive interference wave may be produced as the alternative output  110 ,  108 . That is, a set of inputs  102 ,  104  may produce constructive interference as one of the outputs  108 ,  110 . Accordingly, the other output  110 ,  108  would be a destructive interference wave. However, by manipulating the phase relationship between the beams  102 ,  104 , the constructive interference wave may be produced in the opposite complementary output  110 ,  108 , with a destructive interference wave in its opposite complement  108 ,  110 .  
         [0158]    Referring to FIG. 18, daughter signals  48   a ,  48   b  are illustrated as they may appear in analog format. Each of the daughter pulses  48   a ,  48   b  is separated from the other by a time differential  49 . The coherence time  154  of a photonic source is related to the coherence length by a constant value in any given uniform transmission medium. The coherence time of the source producing a parent of the daughter signals  48  should be less than the smallest time differential  49  used to separate corresponding, coherent, daughter pulses  48   a ,  48   b.    
         [0159]    As a practical matter, the coherence time  154  is actually a coherence time  154  associated with the originating photonic source that originally spawned a parent signal  24  from which the daughter signals  48  were derived. If the coherence time  154  becomes longer than the minimum time differential  49  used, then a danger of coherence between non-corresponding portions of the daughter signals  48   a ,  48   b  is a serious concern that may cause unwanted interference and frustrate proper encoding and decoding of the daughter signals  48 .  
         [0160]    Thus, analog daughter signals  48  are suitable, and can achieve the same result accomplished by digital or pulsed signals. An apparatus and method in accordance with the invention can process analog signals, digital signals, pulsed signals, multi-level semaphore signals, images, and so forth.  
         [0161]    Referring to FIG. 19, a multi-level semaphore  155  may be characterized by an energy sum  156 . The energy sum  156  may be envisioned as a graph integrating the energy from two multi-level semaphore signals. In the embodiment of FIG. 19, a daughter signal  48   a  begins at a starting point  157 . At a time differential  49  later, a start point  158  begins a daughter signal  48   b . Again, the coherence time  154  is less than the time differential  49 .  
         [0162]    Meanwhile, the total energy sum  156  follows the first daughter signal  48   a , follows the superposition thereof with the second daughter signal  48   b , and terminates with the amplitude of the second daughter signal alone after the end point  162  of the first daughter signal  48   a . In a circumstance existing between the starting point  158  that initiates the second daughter pulse  48   b  during a portion of the first daughter pulse  48   a , and up until an ending point  162 , the noninterferometric energy sum  156  represents total photonic signal intensity. Yet, because the contributions from each of the daughter pulses are incoherent during the overlapping time  158  to  162 , interference is not manifest. However, when the delay  49  is corrected in the receiver, interference occurs between matching wave components such as the components  157 - 158  representing the waveform in the output. One virtue of an approach as illustrated in FIG. 19, involving multi-level semaphore daughter signals is the potential for encoding additional information in the shape of the signal.  
         [0163]    Referring to FIG. 20, an alternative embodiment of a time-variant wave form  166  illustrates an amplitude that varies over time, and varies also with each of a variety of frequencies within its domain. Variations in the amplitude  165  over time  163 , throughout a number of different frequencies  167 , the wave form  164  may embody information in the variations available in a host of variable parameters. Thus, a method and apparatus in accordance with the invention, when used to operate with waveforms similar to those illustrated in the wave form  164  of FIG. 20, transmit and receive (encode and decode) multi-spectral, time-varying, amplitude-modulated, phase-modulated, spatially-distributed (image) information. (Not all of the available parameters need to be used in encoding information.) Nevertheless, as illustrated in FIG. 20, the instantaneous samples  168   a ,  168   b ,  168   c ,  168   d  illustrate that modulation in any available domain may be relied upon, encoded, decoded, and multiplexed. Each waveform  164  has a unique organization in the time domain, frequency domain and amplitude domain. It is, therefore, much like a unique fingerprint of the waveform. An apparatus and method in accordance with the invention duplicates, transmits, and then receives such a complex waveform, extracting it from the conglomerate of noise and other multiplexing signals. This is accomplished by reconstituting (reconstructing) the same wave form, by matching the fingerprint-like daughter pulses and outputting that which matches.  
         [0164]    Referring to FIG. 21, a decoder  14  is illustrated, managing daughter signals  48 , such as might be generated in an apparatus illustrated in FIG. 7 a . In the embodiment of FIG. 21, daughter signals  48   a ,  48   b  enter a beam splitter  98 . Granddaughter signals  126 ,  128  exactly matching the coherence and other wave characteristics of the daughter signals  48   a ,  48   b  (absent amplitude) pass through a direct path  102  and a delayed path  104 , including the spatial and color relationships indicative of an image.  
         [0165]    As described for other, simpler signals and pulses, the image signals  126 ,  128  are reconstituted in a coincidence detection interferometer  100 . Accordingly, in one embodiment, a complementary output  108  provides a constructive interference region  130 , flanked by non-interfering portions  132 ,  134 . Similarly, through another complementary output  110 , appears (or perhaps more properly disappears) a destructive interference portion  136 , flanked by unaffected noninterference portions  132 ,  134 . In certain embodiments, a differential amplitude may be detected between the constructive interference portion  130  of the complementary output  108 , and the destructive interference  136  of the other complementary output  110 . Thus, as illustrated in FIG. 21, the photonic apparatus  10 , particularly the encoders  12  and decoders  14 , can handle photonic signals regardless of their spatial distribution, time variance, or spectral extent. The destructive interference portion  136  is illustrated by an outline in FIG. 21. However, when the decoder  14 , in accordance with the invention, is optimally tuned, the destructive interference region  136  is actually an absence of a signal. Nevertheless, that absence may be detectable with respect to the constructive interference portion  130 , and even, in certain embodiments, with respect to the noninterference portions  132 ,  134 , which actually have a signal value. Nevertheless, the major value is that differentiation between a constructive interference portion  130 , and a destructive portion  136  can be detected and consequently, utilized.  
         [0166]    It is no exaggeration to state that image-domain multiplexing provides massive bandwidth available only through such parallel processing. Such processing can be synchronized with other simultaneously multiplexed information in other domains. Multiplexing may be compounded by delay-domain multiplexing. Compounded multiplexing may involve domains such as delay-domain, frequency, time, polarization, image-domain, and the like.  
         [0167]    An apparatus and method in accordance with the invention provide a practical way to implement bandwidths that other technologies have never contemplated. By coordinating information being multiplexed within various domains, synchronization of highly disparate types of information is tractable. For example, routing, data processing, various control instructions, hypertext, sound, background information, hierarchically databasing, and images may all be synchronized within the massive bandwidth available in accordance with the invention.  
         [0168]    Thus, rather than simply providing a sound and image track as is done with video systems and movies, multiple streams of data may be synchronized for any purpose. For example, image data and reference information may be transmitted with sound, image overlays, and database interaction control data on a single stream of multiplexed information.  
         [0169]    Potential applications include simply increasing bandwidth to comparatively massive proportions in a fully photonic, image switching system for supporting a holographic television system would overpower conventional technologies, but be highly tractable in accordance with the invention. Similarly, parallel processing of information management systems becomes almost trivial within the massive bandwidth available for a photonic computing system.  
         [0170]    Likewise, a “holodeck” image control and projection system can be supported by an apparatus in accordance with the invention. Mass data storage with light-speed retrieval systems is contemplated. Parallel image, pattern recognition within databases may increase by many orders of magnitude both the size of the database, and the speed at which data can be made available.  
         [0171]    Moreover, processing methods such as searching may be executed by image recognition at very high bandwidths of reviewed data, rather than the slower conventional systems currently used. Simultaneous examination of multiple petabyte databases may finally be tractable. Thus, an apparatus and method in accordance with the invention appears entirely capable of fully saturating virtually any current photonic transmission media, with precise, coordinated, multi-domain, information routing and control.  
         [0172]    Not only can bandwidth be increased, but data can be encoded to pass a maximum amount of information over the available bandwidth. Thus, an apparatus and method in accordance with the invention provide an enabling technology for deployment of photonic encoding, transmission, and decoding systems for telecommunications in general.  
         [0173]    Referring to FIGS. 22, 23A, and  23 B, processors  170  may receive and “post-process” the complementary outputs  108 ,  110 . In the embodiment of FIG. 22, the signals  108 ,  110  are illustrated schematically, borrowing the nomenclature (schematic illustration elements) from conventional digital logic. Accordingly, for example, the complementary output  108  is passed to a first AND gate  176 , and simultaneously to an inverter  174   b.    
         [0174]    Meanwhile, the photonic, complementary output  110  is provided to the AND gate  176   b  and the inverter  174   b . All the elements of FIG. 22 are photonic, and thus physical systems for providing these digital functions may be referenced in previous work of applicant. Accordingly, the outputs  178   a ,  178   b  provide differential detection of the signals  108 ,  110 .  
         [0175]    For example, if the complementary output  108  provides a constructive interference signal, and the complementary output  110  provides destructive interference, then the output  178   a  provides an output, indicating differential detection between the signals  108 ,  110 . Similarly, if the complementary output  110  receives a constructive interference signal, then the complementary output  108  receives a destructive interference output.  
         [0176]    Accordingly, the output  178   b  of the AND gate  176   b  provides an output, indicating a differential between the signals  108 ,  110 . Absent a full constructive interference or destructive interference in one of the complementary outputs  108 ,  110  and the opposite condition in the other complementary output  110 ,  108 , no output arrives at either output line  178   a ,  178   b . Meanwhile, an optional 2-input, OR gate connected to the outputs  178   a ,  178   b  provides a complete differential detection mechanism.  
         [0177]    Nevertheless, the photonic signals may be taken directly from the outputs  178 . As illustrated in FIG. 22, the channels  178   a ,  178   b  provides information regarding which phase relationship exits between the daughter signals  48   a ,  48   b . Accordingly, phase detection is available through the apparatus  170 . Thus, the processor  170  provides two-channel output when the input is appropriately modulated in phase.  
         [0178]    Referring to FIG. 23, a processor  170  for electronic processing receives the complementary outputs  108 ,  110  into detectors  180   a ,  180   b , which may typically be embodied as photodiodes  180   a ,  180   b . Accordingly, the outputs  108 ,  110  are converted to electronic outputs  182   a ,  182   b  reflecting the content of the outputs  108 ,  110 . In classical terminology, the signals  108 ,  110  have been detected electronically.  
         [0179]    The signals  182   a ,  182   b  are provided to AND gates  186   a    186   b  as illustrated. Accordingly, the AND gate  186   a  receives the signal  182   a , and the signal  182   b  through an inverter  184   a . Similarly, the AND gate  186   b  receives the signal  182   b , and the signal  182   a  through an inverter  184   b . Accordingly, the outputs  180   a ,  180   b  perform precisely the same functionality as the outputs  178   a    178   b , respectively in the illustration of FIG. 22. Nevertheless, the apparatus of FIG. 22 is a fully photonic apparatus, whereas the apparatus of FIG. 23 is electronic, after receiving the original photonic signals  108 ,  110 .  
         [0180]    Thus, the processor  170  of FIG. 22 receives photonic inputs  108 ,  110 , conducts photonic processing, and provides photonic outputs  178   a ,  178   b . By contrast, the processor  170  of FIG. 23 receives photonic inputs  108 ,  110 , provides electronic processing through the electronic AND gates  186   a ,  186   b  and inverters  184   a ,  184   b  and provides electronic outputs  188   a ,  188   b . Thus, the apparatus of FIG. 22 is a fully photonic processor  170 . Meanwhile, the processor  170  of FIG. 23 receives photonic inputs, but is a fundamentally electronic processor otherwise.  
         [0181]    Numerous applications exist for an apparatus  10  in accordance with the invention. Moreover, numerous specific benefits accrue as a result of implementing photonic encoding and decoding in accordance with the invention.  
         [0182]    An apparatus and method in accordance with the invention provide cycle-for-cycle levels of granularity in modulation or distinction of signals. A maximum rate of data transfer in a carrier (photonic carrier) may be possible since resolutions down to an individual wavelength may be used to transfer a single bit of information. Similarly, because of this high rate of resolution, a greater number of multiplexed channels may be available. That is, if resolution down to a single wavelength is possible for data, then switching data between channels, or multiplexing bits among channels, may be completed on an individual cycle-by-cycle basis.  
         [0183]    Hardware transparency is always a valuable feature, and more so as fiber optics require higher bandwidths. Removing electronic components, and removing electronic signal processing with its delays is a substantial advantage. In certain apparatus in accordance with the invention, analog, digital, multi-level semaphore signals, and the like may all be transmitted, along with images, or serial data. Data may be modulated by amplitude modulation, frequency modulation, phase modulation, pulsing, spatial distribution or modulation, and polarization modulation as well. Various protocols and bit rates may be used, since the apparatus is completely transparent thereto. Synchronous or asynchronous communication may be possible, including streaming data asynchronously, and simply interpreting it with a decoder  14 . Correlation may be accommodated so long as coherency is appropriate for the time delay involved in the two streamed daughter signals  48 . Narrow band and broadband communications may be promoted, including stretching and narrowing of pulses, according to the size of a pulse, and the relative overlap between two daughter pulses  48   a ,  48   b.    
         [0184]    Sources may include any spectrum from sunlight to microwave, including lasers, light emitting diodes, and other photonic signal sources. Moreover, pulses may be configured to be long, may be stretched to appear long, and thus interface with legacy equipment, or may be modified to become very short, by relying on only a short region of interference between two coherent daughter signals.  
         [0185]    Whereas coherence length has been preferred to be as long as feasible, in prior art systems, an apparatus in accordance with the invention can actually benefit from a very short coherence length. As discussed, coherence time and coherence length are related by a constant, the speed of light, in any particular medium. Thus, an apparatus and method in accordance with the invention will permit the use of continuous analog signals.  
         [0186]    Moreover, less expensive signal sources may be utilized, since coherence and timing prevent confusion and crosstalk. Virtually any variety of spectral fingerprints, and timing delays, which may be produced on some type of a regular or pseudo-random basis, may be used to provide unique fingerprints for communications. The limited ability of conventional signal time-frame techniques in digital communications to reduce ambiguities, and to verify sending and receiving, may be avoided by the apparatus of the invention.  
         [0187]    Moreover, in the instant devices, in accordance with the invention, frame ambiguities within the time frame of any particular signal of interest or pulse may be reduced by the nature of the short coherence length, the signal delay times, and the signal profile. Due to various factors, including the ability to match pulse lengths, and the like, an apparatus in accordance with the invention can connect to legacy equipment such as the OC-48, and the OC-192 protocols. The short coherence length, and the ease with which signals can be distinguished from one another provides for higher numbers of multiplexed channels over the same number of lines. Again, due to the short coherence length and coherence time, coherent noise may be reduced substantially.  
         [0188]    Modularization of information may be provided in such a way that individual messages may be provided in substantially any length, and may be routed to substantially any destination by broadcast routing. However, in terms of modularization of hardware, broadcast routing is available, without requiring dedicated trunk channels. Broadcast routing may be virtual at both a sending end and a receiving end, with a single trunk carrying the multiplexed information.  
         [0189]    Thus, an apparatus in accordance with the invention produces virtual fibers. The fibers are not actually unique, but rather carry such a high bandwidth of communication, and such a minutely differentiable amount of information, that routing to a particular destination may be done at a higher bandwidth, and may be done absolutely by virtue of time delays, coherencies, and the like inherent in hardware design for particular channels. Thus, a high degree of isolation between channels, and, in some circumstances, an absolute novelty between channels may be available.  
         [0190]    Additional modules may be added at a single station, in order to provide additional bandwidth, without necessarily affecting the remaining bandwidth of a connecting trunk. Thus, in sending or receiving mode, and not necessarily in both at once, modules in accordance with the invention may be configured in series and in parallel to create complex networks to direct and encode or decode messages, or to simply add additional bandwidth. Thus, as long as bandwidth is available in a trunk, various encoders and decoders may be cascaded or connected in series or parallel in order to optimize the use of available bandwidth.  
         [0191]    Particularly, because of the high degree of isolation of channels, additional channels can be added and subtracted at will from different geographical locations. In accordance with the invention, apparatus embodying decoders and encoders as described herein may be configured to unbundle individual bits. Bits can be rebundled into packets and encoded with headers to be routed over photonic networks. In certain embodiments, an apparatus in accordance with the invention may be configured as a fully optical, time-division, multiplexing system. Alternatively, an apparatus in accordance with the invention may neatly interface with legacy multiplexing equipment. The device can be configured to perform as a drop or add device for adding and dropping channels.  
         [0192]    Due to the adjustable delay feature, the apparatus may be tuned such that both transmitters and receivers are selectively interactive with other receivers and transmitters, respectively. Thus, devices may be configured to be tuned to channels temporarily as one would tune a radio.  
         [0193]    By contrast, delays may be embodied in fixed hardware. Accordingly, snap-in or snap-out methods may be used to input delays, much as crystal-controlled channels may be set in radios. Accordingly, such hardware may be less subject to vibration and thermal variation. Meanwhile, channels may be pre-selected to be dedicated to certain locations or hardware.  
         [0194]    Other applications for an apparatus  10  in accordance with the invention may include broadcast routing. Broadcast routing may eliminate the need for packet routing in many networks by providing virtual direct fibers. The fibers are not actually direct, but unused bandwidth may be used by adding and subtracting modules as needed. Accordingly, bandwidth may be provided as needed anywhere. Also such a system may consolidate information from diverse locations into a few locations.  
         [0195]    For example, various sensor information from remote parts of an apparatus, operational plant, industry, building, aircraft, watercraft, automobile, or the like, may be multiplexed over a single lightweight fiber displayed in a single control location. In another example, an aircraft may be configured to have multiple signals multiplexed over a single lightweight fiber displayed through a compact cockpit display. Similarly, controls for a physical plant may be consolidated by a small number of fibers into a central control room. In other embodiments, information may be dispersed. Control information from a device or control center may be dispersed through various hardware that needs remote control.  
         [0196]    In other embodiments, information may be consolidated from electrical meters to a central office. Alternatively, fiber cables, individual television channels or bundles of television channels may be sold in a single package that can be multiplexed over a single actual transmission channel. A subscribers decoder may have an appropriate delay installed in order to receive that subscribers chosen signals.  
         [0197]    In certain embodiments, signal swapping (sequencing) may double the bandwidth available in an apparatus in accordance with the invention. Fewer decoder components, with multiple channels on a single photonic transistor may be available.  
         [0198]    Images may actually be multiplexed. For example, the beam profile integrity, including the actual intensities or amplitudes of signals distributed throughout the spatial distribution of a beam, may be maintained for free-space interconnections, and wireless applications using longer wave energy. Multiple parallel simultaneous signals may be provided for each individual delay time. Thus, full image routing may be available, interfaces with coherent image transmission may be available through coherent fiber bundles, and so forth. In certain embodiments, a single composite fiber may actually transmit an image, collimated and then focused on an aperture for a single fiber.  
         [0199]    Phase sensitive or phase insensitive components may be utilized. Moreover, multiple daughter pulses or daughter signals may increase signal-to noise ratios. Additional address coding for interaction with complex networks may be available by suitable modulation outside of the actual content that would normally be associated with a header or address portion of a transmitted signal. That is, high-frequency modulation or other modulation may be used for signal addressing, independent of the content. Encoding methods may include phase encoding, polarization encoding, sequence encoding, as well as the time and frequency encoding mentioned.  
         [0200]    The degradation of signals that is a bane to current fiber optic technology may actually present little or no problem in an apparatus in accordance with the invention. The degradation of daughter signals from a common parent should be substantially identical, thus allowing for recovery of data at longer distances, or through dispersion, or other distortion, that would be otherwise unusable in other environments. One of the major efforts of fiber optic technology is correcting for dispersion. An apparatus in accordance with the invention, dispersion can be used to spread signals, or signals may be recovered and reconstituted from daughter signals at longer distances than are currently accessible, even with the same light sources and fiber technology.  
         [0201]    In certain embodiments, additional security may be available by sending daughter signals through separate routes. Phase matching may be accomplished by the tuning processes discussed above. Moreover, a fingerprint between two daughter signals is an encryption concept similar to a one-time key or shared secret. Thus, hopping through various time delays may effectively encrypt information, thus making it a highly-time-sensitive cryptographic feature. Just as spread-spectrum techniques are used in a frequency domain, an apparatus and method in accordance with the invention may be implemented as a spread-spectrum system in time. That is, the signal is spread in a time domain, rather than being distributed over a frequency domain.  
         [0202]    As signal processing needs are always driven by a need for real-time speeds, a decoder with an optical output can be used as a filter to remove specific delay information among multiplexed signals. Moreover, wireless transmissions may be effected on a single frequency, for telephones, data transceivers, or the like.  
         [0203]    Multiple communications units may actually operate on the same frequency. Unlike conventional radios, and cellular phones, due to the high bandwidth of such a photonic system, the time delays and high bandwidth of an apparatus and method in accordance with the invention can support multiple communications and be multiplexed at extremely high speeds, which will not affect the apparent content of the transmissions, due to the high photonic bandwidth of such a system. Since no electronic switching is required, the speeds of “administration” of the signals are substantially eliminated. For this and other reasons, legacy equipment such as the legacy optical equipment, legacy electronic equipment, signals such as SONET, ATM, and the like, may all be interfaced with an apparatus in accordance with the invention. Moreover, as photonics become ubiquitous, totally-photonic networks may be created.  
         [0204]    New devices may be enabled by the apparatus  10 . For example, some light encoders may be used in solar-powered, remote telephone systems, relying on fiber, and even using sunlight as a photonic source. Thus, non-powered systems may be laid, which are only powered during actual operation. In other developments, using different delay channels, rather than a phone number, may encode messages directly. Encoding occurs at a hand set, making a central office switching concept obsolete. In certain devices, a source may be located at some location other than at an encoder, or even at a decoder, by sending light through a fiber, through the encoder, and then reflecting the light back into the encoder in the forward direction of a modulating mechanism. Such a mechanism could be used for light-weight inexpensive communication with undersea divers, distance habitats, or into places requiring remote sensing, yet in which electronic equipment is difficult or dangerous to place.  
         [0205]    In some very pedestrian applications such as sensing the fuel level in an aircraft fuel tank or in multiple tanks, simple fibers may receive light signals from an encoder, reflecting the same back to a decoder, depending on whether or not the index of refraction of the surrounding medium is comparatively high or low (detecting the density of a surrounding medium), thus detecting liquid or air. Rather than using bundles of cable or fibers, a single fiber may conduct sufficient information.  
         [0206]    In other embodiments, a photonic burst generator may use a beat frequency between two sources, mismatched in order to provide the differential frequency that is so common in acoustics. Such a device may enhance performance of differential delay (delay-domain) multiplexing systems. Moreover, since the sources of photonic signals may be inexpensive lasers, cost may be substantially reduced.  
         [0207]    Rather than matching lasers closely, lasers that are badly mismatched may actually become the norm, providing higher bandwidth in the beat frequency. Such a device actually reduces the energy level in a transmission medium by removing the constant presence of a carrier signal, and replacing it with a very short burst that occurs in a pseudo-random manner, thus providing much shorter bursts of energy in the signals in the apparatus  10 . Moreover, such a mechanism may allow for more channels by providing, again, much shorter pulses. Since the apparatus  10  in accordance with the invention can deal with pulse lengths of an order of magnitude of a single wavelength, no other practical limits seem to constrain the shortness of a particular bit signal.  
         [0208]    In certain embodiments, a non-return-to-zero type of pulsing system may enhance performance of differential delay multiplexing systems. For example, in such a system, inexpensive lasers or direct optical inputs may be relied upon. Again, since a non-return-to-zero mechanism may be used, the overall energy level for transmission may be minimized. Moreover, the transmission bandwidth requirement is minimized. Again, such an apparatus allows for more channels, reduces the problems with chromatic dispersion, and actually benefits therefrom. For example, such an apparatus may use chromatic dispersion to assist in interfacing with the slower electronic components, thus having a naturally built-in method for pulse stretching. Moreover, such an apparatus may connect directly to legacy equipment such as the devices operating under the protocols of OC-192 and OC-48, or higher.  
         [0209]    Referring to FIG. 24, a drop-rearrange-add apparatus is illustrated for the bundling, unbundling, and rebundling of information, as packets, channels, or the like. The apparatus  190  of FIG. 24 may serve to dynamically configure a router, or to provision a network with channels. By providing adjustability of time delays, by any of the mechanisms discussed herebefore, various lines  192 ,  194 ,  196 ,  198  may be interconnected to receive selected sets of signals.  
         [0210]    That is, channels may be created by virtue of the uniqueness of a time delay associated with a pair of “double-pulsed” signals. By providing an additional variable to work with, a time delay, creating a time-delay domain in which to operate an apparatus  190 , new operational characteristics may be defined by that new variable. Thus, a time-delay or a delay-domain multiplexing scheme may rely on the uniqueness of time-delays in order to define channels. Since a time-delay is not exclusive of a frequency (wavelength) or an ordinary time-division multiplexing scheme, then a delay-domain multiplexer can operate in tandem with other wave-division multiplexers and time-division multiplexers of the prior art. Moreover, a delay-domain multiplexer may operate with analog equipment as well.  
         [0211]    In one embodiment, various decoders  14  may be provided with unique delays  200 , 202 , 204 . Associated with each decoder  200 ,  202 ,  204  is a resulting signal  201 ,  203 ,  205 , respectively. Thus original information provided in the line  194  is decoded by the decoders  14  to create individual delays  200 ,  202 ,  204  which may also be thought of as individual channels  200 ,  202 ,  204 , respectively. Accordingly, separated signals  201 ,  203 ,  205 , respectively, pass from the decoders  14  for re-encoding by the encoders  12 . Thus, content can be routed from one channel  200 ,  202 ,  204 , to another channel  206 ,  208 ,  210 .  
         [0212]    Meanwhile, the delays  206 ,  208 ,  210  (channels) may each be directed or redirected then to another line  196 ,  198  as desired. Of course, switches may be added to the lines  196 ,  198  in order to reroute signals thereon. Although an encoded signal must be decoded by a decoder having the same effective time delay  49 , at re-encoding a new delay  49  may be used in order to create a signal and a new channel.  
         [0213]    Referring to FIG. 24, the delay  204  in the apparatus  190  must correspond to a previously encounter delay  49  by which the signal was encoded. However, the signal  205  may be encoded by any arbitrary time delay  210  before being launched into the carrier medium  198  or fiber  198 , for example. Thus, the D 3  channel  204  has been routed away from the other channels  200 ,  202 . Effectively, in the apparatus  190 , the channel  204  is dropped, by being re-encoded as a channel  210 . The channel  210  is rerouted into a new carrier medium or fiber  198 .  
         [0214]    Meanwhile, the channel  200  is re-encoded as the new channel  206 . The delay  200  is not the same as the delay  206 , and thus, the delay  200  is available again for output onto the line  196  by a different encoder  12 , using the delay  211  identical to the delay  200 . The new line  198  can encode with the delay  210 , identical to the delay  200 , and the delay  211  since the lines  196  and  198  are distinct.  
         [0215]    Thus, the information is unbundled, some is dropped, some is rearranged, and some is added, and all is rebundled for output. That is, for example, the channel  204 , is dropped, the channels  200 ,  202  are rearranged, and the channel  211  is added to the net flow of information passing from the line  194  through to the line  196 .  
         [0216]    Referring to FIGS.  25 - 26 , compounded multiplexing systems include delay-domain multiplexers compounded (in series, parallel, or both) with multiplexers from other domains such as frequency, time-division, and so forth. A variety of encoders  12 , may each be provided with an appropriate wavelength  212 . In one embodiment, a series of encoders  12   a ,  12   b ,  12   c  may have a shared wavelength  212   a . Another series of encoders  12   d ,  12   e  may receive signals having a wavelength  212   b . Although sharing a particular wavelength  212   a , the individual lines  46   a ,  46   b ,  46   c  carry their own distinct information. Similarly, the lines  46   d ,  46   e  carry their own individual information, but each uses the same wavelength  212   b.    
         [0217]    The encoders  12   a ,  12   b ,  12   c  may be thought of as channel  12   a ,  12   b ,  12   c  each having its own individual delay  49 . Accordingly, each of the encoders  12   a ,  12   b ,  12   c  is connected through the various junctions  28  to provide an input having a single wavelength  212   a  fed to the wave-division multiplexer  214 . Similarly, each of the encoders  12   d ,  12   e  may be thought of as a single channel  12   d ,  12   e . Accordingly, each of those channels  12   d ,  12   e  is combined through a junction  28  in order to provide a signal having a single wavelength  212   b  fed to the wave-division multiplexer  214 .  
         [0218]    Thus, two inputs, each operating at a distinct wavelength  212   a ,  212   b , respectively may be received by a wave-division multiplexer  214 . The wave-division multiplexer  214  then provides an output that effectively is a compound signal, having different information as the various wavelengths  212   a ,  212   b , and so forth, all carried by the main trunk  30  or carrier medium  30 . All the information carried in the line  30  is encoded in both a frequency domain by the wave-division multiplexer, and in the delay domain of the present invention.  
         [0219]    At a destination, a wave-division demultiplexer  216  divides the incoming signals according to their wavelengths  212   a ,  212   b . Accordingly, each of the decoders  14   a ,  14   b ,  14   c  receives a signal through a junction  32  at a wavelength  212   a . Likewise, each of the decoders  14   d ,  14   e  receives a signal through a junction  32  at a wavelength  212   b.    
         [0220]    Information is recovered from the delay domain by the decoders  14   a ,  14   b ,  14   c  to provide outputs  218   a ,  218   b ,  218   c , respectively. Similarly, the information is recovered from the delay domain by the decoders  14   d ,  14   e  to provide the outputs  218   d ,  218   e , respectively. Thus, in one embodiment of an apparatus and method in accordance with the invention, information is combined in the delay domain by the encoder  12 , and then further combined in the frequency domain by the wave-division multiplexer  214 , then re-divided in the frequency domain by the demultiplexer  216  and re-divided in the delay domain by the decoders  14 .  
         [0221]    Referring to FIG. 26, while continuing to refer generally to FIG. 25, and FIGS.  1 - 24 , the central carrier  30  of FIG. 26 may be thought of as a photonic network carrier medium  30 . By contrast, the carrier medium  30  of FIG. 25 may be a legacy carrier medium  30 . Accordingly, in the apparatus of FIG. 25, the encoders  12  and decoders  14  are compounding on legacy equipment operating in the frequency domain, whereas in the apparatus of FIG. 26, the legacy equipment operating in the frequency domain is compounded on a delay-domain, photonic network.  
         [0222]    Because the encoders  12   a - 12   f  and decoders  14   a - 14   f , in accordance with the invention, are independent of protocol, format, and other legacy encoding processes, the apparatus of FIG. 26 can compound, over a single network (e.g. trunk carrier medium  30 ), signals  46  from a variety of legacy equipment. Legacy equipment may include wave-division multiplexers  214   a ,  214   b ,  214   c ,  214   d , time-division multiplexers  214   e , as well as other apparatus.  
         [0223]    For example, a non-return-to-zero (NRZ) such as an OC-48, or other SONET network equipment, and the like, may be accommodated. The NRZ sources  220  may be multiplexed by the multiplexer  214  to result in NRZ outputs  221  after decoding. A differentiator  222 , in accordance with the invention, may be connected to a delay-domain multiplexer  12   a  operates in combination with the flip flops  224  to recover the NRZ outputs.  
         [0224]    Meanwhile, an analog system  226  may connect to one of the delay-domain encoders  12   f . Signals from the analog system  226 , as a unique channel, may be recovered by a destination analog system  228  after a decoder  14   f , in accordance with the invention.  
         [0225]    Referring to FIG. 27, one embodiment of an apparatus and method in accordance with the invention may combine features of the encoder module  50  of FIG. 4 and a decoder  14 , in accordance with FIG. 12. In the embodiment of FIG. 27, a splitter  52  provides daughter pulses  48   a ,  48   b . The daughter pulses  48   a ,  48   b  travel down different carrier media  30   a ,  30   b . The carriers  30   a ,  30   b  may actually be identical or different media, but are distinct hardware. In one presently preferred embodiment, both are identical. For example, one carrier  30  may be free space and another carrier may be glass fiber, but both, in one presently preferred embodiment, are photonic carrier media.  
         [0226]    The signal  48   a  or daughter pulse  48   a  arrives at a coincidence detection interferometer  100 . Meanwhile, the daughter pulse  48   b  arrives first at an adjustable time delay  106 . The adjustable time delay  106  provides a correction of the delay between the daughter pulses  48   a ,  48   b , in order to properly produce coincidence at the points of its coincidence detection interferometer  100 . Accordingly, complementary outputs  108 ,  110  may result from constructive interference and destructive interference in accordance with the invention.  
         [0227]    Referring to FIGS.  28 - 29 , a photonic NRZ input source  220  may provide a signal  230  as in input to a photonic differentiator  222 . In the differentiator  222 , the NRZ input signal  230  strikes a splitter  232  which divides the pulse into daughter pulses traveling over a direct path  102  and a delay path  104 . The delay path adds time to a daughter signal by a suitable mechanism, as discussed above, such as mirrors  234 . Eventually, the signal from the direct path  102  and the delay path  104  arrive at a photonic transistor  236 . Photonic transistor provides, or may provide, both a constructive interference output and a destructive interference output.  
         [0228]    In the apparatus of FIG. 28, the output that provides destructive interference is selected as the output signal  238   a . Since destructive interference is selected, then the absence of a signal provides a zero. Meanwhile, the presence of destructive interference provides a zero condition. However, in those transition regions  239   a ,  239   b  in which destructive interference is absence, the time delay between the daughter pulses provides an offset resulting in a single short pulse  238   a ,  238   b  for each transition that occurs in the original NRZ input  230 .  
         [0229]    A major advantage of differentiation in accordance with the invention is that the net energy transferred or launched through the carrier  30 , is greatly reduced. Reducing the overall energy level per channel, and thus the overall energy within a carrier medium  30 , allows carrying more channels of information.  
         [0230]    In certain embodiments, the differentiator  222  may be adjustable. Also, in certain embodiments, the differentiator  222  may be configured to provide extremely precise time delays  49 , in order to precisely control the width of the pulses  238   a ,  238   b . Pulses may be controlled for purposes of information interfaces, requiring pulse-width control, or for purposes of reducing overall energy by reducing the width of a pulse, while leaving all information intact.  
         [0231]    Moreover, this manipulation of pulse width effectively controls the energy duty cycle of the apparatus. This is of special advantage in a system that can switch at a resolution of a single wavelength, in accordance with the invention (see e.g. FIGS. 7, 16,  17 ). It is important to note that the short pulses  238   a ,  238   b  are not daughter signals  48  from an encoder  12 . Although daughter pulses may be generated in the differentiator  222 , they have been recombined by the photonic transistor  236 , and exist with an appropriate delay therebetween dictated by the transitions  239   a ,  239   b  corresponding to the NRZ input  230 .  
         [0232]    The time delay  240  between the short pulses  238   a ,  238   b , does not correspond to the time delay  49  created in the differentiator  222 , in association with the daughter signals. Rather, the offset  240  or time delay  240  corresponds to the beginning time  242   a , and ending time  242   b , of the NRZ input signal  230 . Thus, the delay  240  between the short pulses  238   a ,  238   b  is dictated not be the differentiator, but by the input data of the signal  230 , not by the hardware of the differentiator  222 . Thus, the delay  240  is a data phenomenon, not a hardware phenomenon.  
         [0233]    The encoder  12  operates as discussed herein, to encode each short pulse  238   a ,  238   b , independently as separate, distinct parent signals  46  (pulses  46 ), effectively unrelated to one another for purposes of encoding. Accordingly, the decoder  14  provides fully reconstituted short pulses  238   a ,  238   b  as inputs to a flip flop  224 . In a fully photonic system, the flip flop  224  is a photonic flip flop. In an electro optical apparatus, the flip flop  224  is an electronic flip flop. The output  221  of the flip flop  224  is a reconstituted NRZ signal  230 . Of course, the flip flop  224  may be initialized in accordance with standard practice, as known in the art.  
         [0234]    When an invention in accordance with FIG. 28 is used in a compound domain environment, (e.g. FIG. 26) a legacy multiplexer  214  may be inserted between multiple NRZ sources  220 , and a differentiator  222 . Correspondingly, a legacy demultiplexer  216  may be inserted between a decoder  14 , and multiple flip-flops  224 .  
         [0235]    It is an important feature in at least one embodiment of an apparatus and method in accordance with the present invention that the duty cycle of each datum be reduced leaving an off time  240   a . This not only reduces the amount of energy needed to transmit the data, but makes available an empty time interval immediately following each transmitted pulse. An apparatus may take advantage of this “dead” space in at least two ways.  
         [0236]    For example, when a pulse  238   a  travels through a dispersive medium, various types of dispersion, including may occur. Dispersion types may include chromatic, polarization, and the like, effectively stretch the corresponding received pulse  238   c  into a time period  240   a . Ordinarily, dispersion would cause cross talk with adjacent (in time) bits. The present invention may synchronize a dispersed pulse with an intentional subsequent blank time interval to remedy cross talk between adjacent bit time intervals.  
         [0237]    Also, such newly useful dispersed pulses  238   a  can be directed into a flip flop  224 . Meeting a threshold value at a time  241  changes the state of the flip flop  224 , reproducing the original NRZ signal. Moreover, the internal capacitance of photo diodes need no longer be bothersome in electrooptical embodiments. Capacitance may actually be desirable, providing integration of a pulse  238 . Such integration may aid photodetection. As a result, an apparatus in accordance with the invention can rely on comparatively inexpensive photodiodes having slower speeds than those typically specified to detect short pulses  238 . Meanwhile, problems associated with dispersion are ameliorated.  
         [0238]    Referring to FIGS.  30 - 36 , while continuing to refer generally to FIGS.  1 - 29 , a parent signal  46   a  may enter an encoder  12   a  providing a pair of daughter signals  48   a ,  48   b . Meanwhile, another parent signal  46   b  enters an encoder  12   b  to produce daughter signals  48   c ,  48   d . The time delays  49   a ,  49   b  are substantially equal but different by sufficient time to produce a phase difference of 180 degrees. Thus, the daughter signals  48   a ,  48   b  are in phase with respect to one another, while the daughter pulses  48   c ,  48   d  are out of phase with one another. The sets of daughter signals  48   a ,  48   b  and  48   c ,  48   d  can be combined at a junction  28  or other combining mechanism, and launched into a carrier medium  30  toward a destination. Thus, two, distinct, phase-sequenced channels have been created, using the same effective time-delay  49 , to carry two distinct and disparate signals  46   a ,  46   b.    
         [0239]    Referring to FIG. 31, a high level, schematic, block diagram of a decoder relies on phase sequencing to manage dual channels. A carrier medium  30  may provide an input to a decoder  14 . As discussed hereinabove, complementary outputs  108 ,  110  result from the decoder  14 . The outputs  108 ,  110  are then processed in a processor  170  (see e.g. FIGS.  22 - 23 ) in order to provide reconstituted signals  178   a ,  178   b  corresponding to the parent signals  46   a ,  46   b.    
         [0240]    Referring to FIGS.  32 - 33 , timing diagrams illustrate the decoding in channel separation processes of the apparatus of FIG. 31. The decoder  14  has only a single time-delay  49   a , since the time-delay  49   b  is merely the delay  49   a  shifted in phase by 180 degrees. Referring to FIGS.  32 - 33 , a time-delay  49   a  exists between corresponding locations in granddaughter signals  126 ,  128  from the decoder  14  in the outputs  108 ,  110 , respectively.  
         [0241]    [0241]FIG. 32 illustrates the pair of granddaughter signals  126 ,  128  in phase, while FIG. 33 illustrates the pair of granddaughter signals  126 ,  128  that are out of phase. The direct signal  102  reflects only the delay-time  49   a  between the signals  126 ,  128  (e.g. pulses  126 ,  128 ). Meanwhile, the delayed signal  104  reflects the additional delay of  49   a  applied by the decoder  14 .  
         [0242]    Thus, the leading pulse  126  from the direct path  102  or direct signal  102 , in each case provides no interference, and thus no contribution to the reconstituted signal  178 . Similarly, in each case, the trailing signal  128  from the delayed path  104  or delayed signal  104  produces no interference and thus no contribution to the reconstituted output  178 .  
         [0243]    By contrast, interference between the trailing signal  128  of the direct path  102 , and the leading signal  126  of the delayed path  104  produce destructive interference as the complementary output  108  in a first channel. Similarly, the same two pulses  128 ,  126  provide constructive interference  30  in the complementary output  110 . Accordingly, the reconstituted signal  178   a  of FIG. 32 provides an output pulse  38 .  
         [0244]    Since the granddaughter pulse  128  of the direct path  102  of the second channel illustrated in FIG. 33 is 180 degrees out of phase with the leading granddaughter pulse  126  of the delayed path  104 , the complementary output  108  sees the constructive interference  130 . Thus, the complementary output  110  sees destructive interference  136 . Accordingly, a reconstituted signal  178   b  provides a pulse  38 .  
         [0245]    The differential between the complementary output  110  and the complementary  108  exists in each case (channel), but is reversed in sense to differentiate the two channels. In the illustrated embodiment, the different channels receive the parent signals  46   a ,  46   b  at different times. The value in channeling is to distinguish one result across one path from another result across another path.  
         [0246]    Clearly, in the embodiment of FIGS.  32 - 33 , simultaneous occurrence of both the reconstituted pulses  178   a ,  178   b  would not occur, or rather the pulses  38  would not occur in the reconstituted outputs  178   a ,  178   b . The presence of a constructive interference output and destructive interference output on each of the complementary outputs  108 ,  110 , simultaneously would eliminate any differential therebetween, nullifying the effect.  
         [0247]    Referring to FIG. 34, the encoders  12  reflect two instantiations of the entire apparatus illustrated in FIG. 30, each instantiation being 90 degrees out of phase with the other. Meanwhile, as a decoding mechanism, the apparatus of FIG. 34 contains two complete instantiations of the entire apparatus of FIG. 31, each shifted 90 degrees out of phase with respect to the another. The result is four channels of throughput.  
         [0248]    The inputs  46   a ,  46   b  into the corresponding encoders  12   a ,  12   b  may be thought of as equivalent to those illustrated in FIG. 30. Accordingly, two channels of output are provided, as discussed. However, by providing an encoder  12   c  shifted 90 degrees from the encoder  12   a , and an encoder  12   d  shifted 90 degrees from the encoder  12   b , two additional channels of output are available. By “shifted” is meant not that the first daughter pulse  126  is shifted, but that the phase shift of the second daughter pulse  128  with respect to the first daughter pulse  126  takes on one of four corresponding values, zero, 180 degrees, 90 degrees, or 270 degrees. Accordingly, two pairs of encoders  12  are each producing a trailing daughter pulse  128  that is 180 degrees out of phase with a leading pulse  126 .  
         [0249]    In the apparatus of FIG. 34, two coincidence detection interferometers  100  operate 90 degrees out of phase with respect to one another, due to a phase shifter  244 . Accordingly, four outputs  245   a ,  245   b ,  245   c ,  245   d  result. These may be referred to as quadrature outputs  245 .  
         [0250]    Referring to FIG. 35, a truth table juxtaposes several channels  46   a ,  46   b ,  46   c , 46   d  of inputs as they will be encoded and decoded into different quadrature outputs  245   a ,  245   b ,  245   c ,  245   d . Thus, the quadrature outputs  245  reflect the state of each of the outputs  245 , depending upon which channel  46  is active (contains a data signal).  
         [0251]    Referring to FIG. 36, a timing diagram illustrates the value of each output  245  for a single input, channel four (the input  46   d ) in this example. Timing diagrams like those of FIG. 36 may be illustrated to reflect each of the channels  46  in the truth table of FIG. 35.  
         [0252]    Continuing to refer to FIG. 36 while referring generally to FIGS.  1 - 35 , a time interval  247   a  corresponds to a granddaughter pulse  126  in a direct path  102 , producing no interference, and no differentials between any of the channels  245 , and thus no output  37 . Similarly, during the time interval  247   c , a trailing granddaughter pulse  128  over the delay path  104  produces no interference, and thus no differential between the outputs of the various channels  245 . Therefore, a null value of the output signal  34  results during the time interval  247   c.    
         [0253]    By contrast, during the time interval  247   b , the trailing granddaughter pulse  128  of the direct path  102  is coincident with the leading granddaughter pulse  126  over the delay path  104 , resulting in constructive interference  130  in the output  245   d  and destructive interference  136  in the output  245   c . This produces a differential between the values of the constructive interference  130  and the destructive interference  136 , resulting in an output pulse  38  in the output signal  37 .  
         [0254]    The trailing granddaughter pulse  128  of the direct path  102  and the leading granddaughter pulse  126  of the delay path  104  result in coincidence  246   a ,  246   b  in the outputs  245   a ,  245   b , respectively. However, due to the 90-degree shift in phase, the relative amplitudes are equal in each case, thus producing no differential. Accordingly, the output  248  resulting at the corresponding output  178  (see FIG. 31) will be null.  
         [0255]    That is, depending on which of the channels  46  was providing an input, the corresponding reconstituted parent signal  178  will have a value of the reconstituted pulse  38  in the output  37  that corresponds to the correct reconstituted parent signal  178 . The zero value of the output  248  will correspond to the paired reconstituted parent signal  178  from the same processor  170 . Thus, for example, if a first channel  46   a  has an input, then a paired second channel  46   b  will not. Similarly, if, as illustrated in FIG. 36, a fourth channel  46   d  has an input, then the output  37  has a pulse  38 , while all other channels  46   a ,  46   b ,  46   c  reflect the null value of the output  248 .  
         [0256]    In another way of thinking, if a fourth channel  46   d  is receiving data, then a matched third channel  46   c  has a null output  248  as a result of the process illustrated and explained with respect to FIGS.  32 - 33 . Meanwhile, at the same time, the first and second channels  46   a ,  46   b , respectively have a null value for the output  248 , due to the 90 degree phase shift that produces no differential. Thus, in any pair of channels  46 , when one of the pair is receiving data, its matched companion has destructive interference, resulting in no output from the companion.  
         [0257]    Only one channel  46  of any channel pair (companions)  46   a ,  46   b  or  46   c ,  46   d  in the example, may be used at one time. Any number of sets ( 46   a ,  46   b  is a set,  46   c ,  46   d  is a set) may be used simultaneously.  
         [0258]    Referring to FIG. 37, a polarization splitter  60  relies on the surface  61  to act as a polarization separation surface  61 . Accordingly, an input signal  24  is split between two output signals  48   a ,  48   b . However, the input signal  24  has a horizontal component  252 , and a vertical component  254 . The horizontal component  252  and vertical component  254  are relative to one another, and not relative to absolute space. Nevertheless, in entering the splitter  60 , the horizontal component  252 , and vertical component  254  are or do become defined relative to the separation surface  61 .  
         [0259]    For example, one may think of the axes  253   a ,  253   b ,  253   c , as defining the geometry of the splitter  60 . Thus, the axes  253  form the frame of reference for the geometry of the splitter  60 , and its associated splitting surface  61 . Therefore, regardless of the orientation of the polarization of the input signal  24 , so long as it has at least two orthogonal constituents (components), the plane  61  defines the horizontal component  252  and vertical component  254  in term of itself. The plane  61  controls the separation of the outputs  484   a ,  484   b  having a polarization defined by the reference frame of the axis  253 . Thus, speaking of the polarization of the signal  24  is a matter of convenience. Meanwhile, speaking of the polarization of the outputs  48   a ,  48   b  and their polarization components  252 ,  254  is real and relative to the reference frame of the axes  253 . As a result, the orientations of the horizontal polarization component  252  and the vertical polarization component  254  are anchored in the geometry of the apparatus  10 , of which the splitter  60  is a component.  
         [0260]    Referring to FIG. 38, an input signal  24   a  enters a splitter  60   a , which separates out the signal  256   a , containing the horizontal component  252 , and the signal  256   b  containing the vertical component  254 . The orientation of the horizontal component  252 , and the vertical component  254  represented in the signals  256   a ,  256   b , respectively, is maintained from the splitter  60   a  to the photonic element  56   a , responsible for directing the signals  256  into the carrier medium  30  as sequential daughter signals  256   a ,  256   b . Thus, introduction of the parent signal  24   b  into the splitter  60   b  at an orientation orthogonal to that of the entry of the signal  24   a  into the splitter  60   a , produces splitting at the surface  61   b  at a different set of orientations.  
         [0261]    That is, the horizontal component  252  is embodied in the direct signal  258   a  while the vertical component  254  is embodied in the delayed signal  258   b . As with the signals  256   a ,  256   b , the optical element or photonic element  56   b  (as appropriate) launches the daughter signals  258   a ,  258   b  into the carrier medium  30  via the combiner  28 .  
         [0262]    Significantly, the signal  256   a  leads, having a vertical component  254 , while the horizontal component  252  in the signal  258   a  leads. The delay  49   a  between the signals  256   a , 256   b  results from the fact that the signal  256   a  passes directly from the splitter  60   a  to the photonic element  56   a . Meanwhile, the signal  256   b  passes indirectly through a time delay  49   a  to the photonic element  56   a.    
         [0263]    By contrast, due to the orientation of the incoming signal  24   b , and the orientation of the surface  61   b , the signal  258   a  passes directly from the splitter  60   b  to the photonic element  56   b . Meanwhile, the indirect signal  258   b  passes through the time delay  49   b  on its path to the photonic element  56   b . Accordingly, the signal  258   b  trails the signal  258   a , and embodies the vertical component  254 , in contrast to the relative components  252 ,  254  of the signals  256   a ,  256   b.    
         [0264]    The paths  256   b ,  258   b , or signals  256   b ,  258   b  may be subjected to the corresponding delays  49   a ,  49   b  by any suitable optical elements, including mirrors, optical fibers, changes in refracted indices, and so forth. The significance of the apparatus of FIG. 38 is the creation of two separate channels sending data simultaneously over the carrier medium  30  by virtue of polarization sequencing.  
         [0265]    In one embodiment, the functions of the splitter  60   a  and the splitter  60   b  may be consolidated into a single splitter  60   b . In such an alternative embodiment, one merely need pass a signal  255  directly into the splitter  60   b , as illustrated, to provide the same signal and identical functionality as the signal  24   a . Since the path  255  or input signal  255  is orthogonal to the path and signal  24   b  relative to the surface  61   b , the functionality of this alternative embodiment is identical to that of the twin splitters  60   a ,  60   b . However, one advantage of the illustrated embodiment is that the splitter  60   a  and the splitter  60   b  can be in remote locations with respect to one another. Thus, different locations, even different cities, may be served by the splitters  60   a ,  60   b  acting as encoders  12 .  
         [0266]    Referring to FIG. 39, a double decoder  14  separates polarization sequenced signals  256 ,  258  in order to differentiate two channels of information having the same time delay  49 . The time delays  49   a ,  49   b  in FIG. 38, and the time delay  49  in FIG. 39 are substantially the same.  
         [0267]    The signals  256 , 258  enter the decoder  14  over the carrier medium  30  as multiplexed signals. The decoder  14  is responsible to de-multiplex the two channels. The method for producing the delay  49  may be similar to, or identical to, any of those heretofore discussed, as appropriate. The multiplexed signals  256 ,  258  arriving over the carrier medium  30  are divided by the amplitude splitter  98  between a direct path  102  and a delay path  104 .  
         [0268]    The direct path  102  or direct signal  102  passes into the divider  260  serving as a polarization channel divider  260  (a splitter  60 ) to be split on the basis of polarization between a horizontal component  252  and a vertical component  254 . The horizontal component will be reflected upward toward the component separator (polarization component separator)  266 , while the vertical component  254  will be transmitted through the divider  260  toward the polarization component separator  268  (separator  268 ).  
         [0269]    Meanwhile, the delayed path  104  or delay signal  104  enters the divider  260  orthogonal to the signal  102  or path  102 . Accordingly, the vertical component  254  of the signal  104  is transmitted through the divider  260  toward the separator  266 . By the same token, the horizontal component  252  of the signal  104  is reflected from the surface  61  a toward the separator  268  (polarization component separator  268 ).  
         [0270]    In providing the delay  49 , the decoder  14  of FIG. 39 relies on mirrors  114 ,  116 . Nevertheless, any suitable method discussed herein, or an equivalent known in the art, may suitably provide the delay  49 .  
         [0271]    The functions of the polarization component separators  266 ,  268  are identical. Therefore, the explanation of one, reflects the operation of the other. For example, the intermediate signal  262  represents all signals that may arrive in the illustrated orientation, regardless of channel. Similarly, the intermediate signal  264  represents all signals that may arrive in the illustrated orientation, regardless of channel. The intermediate signal  262  is split by the surface  61   b  into complementary outputs  108   a ,  110   a , having orthogonal polarizations. Similarly, the complementary outputs  108   b ,  110   b  have orthogonal polarizations. The complementary signals  108 ,  110  enter a coincidence detector  270 . Note that the trailing reference letters refer to specific instances of the more generic item identified by the corresponding reference number.  
         [0272]    The coincidence detectors  270   a ,  270   b  may utilize fully photonic configurations (circuitry, components, etc.) or electronic configurations. However, for simplicity and clarity, electronic circuitry is illustrated. Nevertheless, the photonic circuitry for accomplishing the function has been described in the prior art. In the illustrated embodiment, a pair of diodes  272 ,  274  feeding into an AND (e.g. a Boolean AND circuit)  276 . When both complementary outputs  108 ,  110  corresponding to a single channel are “coincident,” a reconstituted parent signal  37  is output from the AND gate  276 . Any other condition produces a null output as the signal  37 .  
         [0273]    Referring to FIGS.  40 - 41 , a timing diagram illustrates the functioning of the apparatus  14  of FIG. 39. The timing relationships of the timing diagram of FIGS.  40 - 41  illustrate why the functioning of the decoder  14  of FIG. 39 produces channeling based on polarization sequencing.  
         [0274]    Referring to FIG. 40, a timing diagram for a first channel provides a direct signal  102  and a delayed signal  104  representing the signal  256  received at the divider  260 . The leading pulse  256   c  contains the vertical component  254 , and the trailing pulse  256   d  contains the horizontal component  252 . Similarly, the leading pulse  256   e  contains the vertical component  254  while the trailing pulse  256   f  contains the horizontal component  252  in the delayed signal  104 .  
         [0275]    In the same fashion, the leading pulse  258   c  contains the horizontal component  252  and the trailing pulse  258   d  contains the vertical component  254 . In like manner for the delayed signal  104 , the leading pulse  258   e  contains the horizontal component  252  while the trailing pulse  258   f  contains the vertical component  254 .  
         [0276]    It is important to remember that each of the signals  102 ,  104  in the timing diagrams of FIGS.  40 - 41  represent granddaughter pulses created by the amplitude splitter  98  of the apparatus  14  (decoder  14 ) of FIG. 39. In any event, the leading and trailing relationship of the vertical and horizontal components of any signal are reversed to differentiate a first channel from a second channel. In certain embodiments, one may refer to this sequencing of polarization as an encoding scheme, and consequently a decoding scheme for a telecommunications network.  
         [0277]    The process of decoding is illustrated by observing its performance during adjacent time intervals  278 ,  280 , 282 . During the time interval  278  the leading pulse  256   c  of the direct signal  102  contains the vertical component  254 . The vertical component  254  is separated by the divider  260  to provide the intermediate signal  264 . The signal energy is then transmitted through to the complementary output  110   b  leaving all the other signals null.  
         [0278]    Similarly, during the time interval  282 , the delay signal  104  contains a trailing pulse  256   f  embodying the horizontal component  252 . Accordingly, the divider  260  outputs the intermediate signal  264  containing the energy of the horizontal component  252 , which is then directed into the separator  268  to be output as the complementary output  108   b . All other signals are null.  
         [0279]    As a result, during these two time intervals  278 ,  282 , the reconstructed parent signal  37   b  is null, as is the reconstructed signal  37   a . During the time interval  280 , coincidence exists between the trailing pulse  256   d  of the direct signal  102 , and the leading pulse  256   e  of the delayed signal  104 . Accordingly, both the horizontal and vertical components  252 ,  254  are present.  
         [0280]    Thus, the energy of both pulses  256   d ,  256   e  may be output as the intermediate signal  262  of a first channel. That energy is separated by the separator  266  into the complementary outputs  108   a ,  110 . Therefore, the coincidence detector  270  detects the coincidence and produces the pulse  38  as the reconstructed parent signal  37   a . The other signals  264 ,  108 ,  110   b ,  37   b  of the second channel are null.  
         [0281]    The response  284   a  corresponds to a first channel, and the response  286   a  represents a second channel, to the signal set  288  received as a multiplexed input. Similarly, the response  284   b  of the first channel, and the response  286   b  of the second channel are in correspondence with the signal set  290  received as a multiplexed input of the second channel.  
         [0282]    The time delays  49  for both channels are identical. Accordingly, during the time interval  278 , the leading pulse  258   c  contains a horizontal component  252  directed into the intermediate signal  262  and subsequently directed to the complementary output  110   a . The remainder of the signals during the time interval  278  are null. Similarly, the trailing pulse  258   e  of the delayed channel  104  contains a vertical component  254  transmitted through (directed to) the intermediate signal  262 . The complementary output  108   a  contains that same energy of the vertical component  254 . The value of all other channels during the time interval  282  is null.  
         [0283]    During the time interval  280 , the coincidence time, the trailing pulse  258   d  of the direct signal  102 , and the leading pulse  268   e  of the delayed signal  104  are directed into the intermediate signal  264  of the second channel. Subsequently, the energy thereof is divided by the separator  268  into the complementary outputs  108   b ,  110   b . The result of the operation of the coincidence detector  270   b  is a reconstituted parent signal  37   b  embodying the pulse  38 .  
         [0284]    Referring to FIGS.  42 - 43 , a method and apparatus are available for narrowing the width of a pulse containing information, such that more pulses may be launched in a carrier medium per unit time, without saturating the carrier medium. Meanwhile, signal-to-noise ratios are maintained, and information is not lost.  
         [0285]    One valuable application of such a method and apparatus is to provide an initial parent pulse  24  suitable for a delay-domain multiplexer in accordance with the invention. An initial photonic input  292  may be thought of as a base or initial parent pulse, which could have been received as a parent pulse  24  into a delay-domain multiplexer  10 . However, the function of the apparatus of FIGS.  42 - 43  is to further reduce such a pulse in width in order to provide an improved parent pulse  24 . Thus, one may think of the input pulse or input signal  292  as a raw pulse of arbitrary width, which width is to be reduced further. Thus, one may think of the apparatus and method of FIGS.  42 - 43  as an improved signal processing device for pre-processing a parent signal  24  prior to entry into a delay-domain multiplexer.  
         [0286]    In the embodiment of FIG. 42, a photonic input  292  is directed toward a partially reflecting mirror  294 . In this particular embodiment, the mirror  294  operates to provide two separate functions at two distinct locations  296 ,  298 . A splitting portion  296  splits the input signal  292  into a transmitted portion  300 , and a reflected portion  302 . The transmitted signal  300  is reflected back from the retroreflecting mirror  304  towards the interferometer portion  298 . The interferometer portion  298  of the mirror  294  transmits a portion of the incoming signal  300 , and reflects a portion  308 .  
         [0287]    Meanwhile, the reflected signal  302  is reflected back from the mirror  306  (a retroreflecting mirror  306 ) to create superposition with the reflected portion  308  of the signal  300 . Accordingly, the interferometer portion  298  provides two complementary outputs  308 ,  310 .  
         [0288]    Referring to FIG. 43, while continuing to refer to FIGS.  1 - 42 , generally, an initial parent pulse  312  may be contained in the input signal  292 . The mirror  294  splits the pulse  312  at the splitting portion  296  to produce two daughter pulses  314   a ,  314   b . Since the mirrors  304 ,  306  are adjustable in their respective adjustability directions  305 ,  307 , the daughter pulses  314   a ,  314   b  may be timed in order to produce an overlap  315 . The overlap  315  may be thought of as an adjustable overlap  315 . One of the outputs  308 , 310  will produce constructive interference, during the overlap  315 , and the other will produce destructive interference during the same time period. The recombined pulse  316  occurs in which ever of the complementary outputs  308 ,  310  produces constructive interference.  
         [0289]    In certain embodiments, the pulse  316  may be input into another pulse concentrator  291  (see FIG. 42), or may be launched directly into a delay-domain multiplexer. In the embodiment of FIG. 43, two passes may occur through the same or different concentrators  291 . A concentrator  291  having a shorter time delay is used for clarity of illustration. The recombined pulse  318   a  is the result (output) of a second concentrator  291 . Further passes through the same or a distinct concentrator  291  are possible, feasible, and, in some cases, recommended. Nevertheless, for the purposes of illustration, the example of FIG. 43 is sufficient.  
         [0290]    The effect of the concentrator  291  is to redistribute the energy from the initial parent pulse  312  between the daughter pulses  314 , and then into the constructive interference portions  317   a  and associated skirts  317   b ,  317   c  of the reconstructive pulse  316 . The effect is to concentrate a greater proportion of the energy into the constructive interference portion  317   a  during the overlap time period  315 .  
         [0291]    Further concentration through a pulse concentrator  291 , having the recombined pulse  316  as an input, produces the second recombined pulse  318   a . In this instance, the constructive interference phenomenon concentrates more energy per unit time in the signal portion  319   a . Interference contributes to the energy per unit time in the shoulders  319   b ,  319   c , as well as in the secondary shoulders  319   f ,  319   g.  However, the most significant signal portion  319   a , best improves the overall signal-to-noise ratio. One may note that the skirts  319   d ,  319   e  occur during times when no constructive interference occurs in any of the concentrators  291 , regardless of how many have been cascaded together.  
         [0292]    An additional benefit may be obtained in certain embodiments of an apparatus  291  in accordance with the invention. The second recombined pulse  318   a  is attenuated to produce the attenuated pulse  318   b . Attenuation may be accomplished through a variety of mechanisms. In certain presently preferred embodiments, attenuation may be accomplished by an attenuator proximate the production of the recombined pulse  318   a.    
         [0293]    In an alternative embodiment, natural attenuation occurring in a transmission line may be relied upon to produce the attenuated pulse  318   b  from the pulse  318   a . Thus, attenuation may be accomplished, respectively, either before or after entry of a pulse  24  into a delay-domain multiplexing encoder  12 . Moreover, attenuation may occur by either natural attenuation of certain transmission media or by inclusion of a specific attenuating device intentionally positioned either before or after an encoder  12 .  
         [0294]    In certain embodiments, such as the configuration of FIG. 26, junctions  28  or combiners  28  may present a certain degree of attenuation or loss of signal. Accordingly, the network of FIG. 26 may take advantage of the loss occurring in the individual combiners  28  in order to produce the attenuated signal  318   b  for launch onto the carrier medium  30 . As a direct, reliable, and even calculable and deterministic result, more encoders  12  may be multiplexed together to feed (launch) information into the carrier medium  30  without saturation. This effect is directly traceable to the overall reduction of energy in each pulse  318   b  transmitted. Due to the accentuated SNR, a detection threshold  320  may easily be met. The remainder of the pulse  318   b  may be discriminated as noise or otherwise ignored as noise would be. Thus, in the time domain  324 , the concentration of signals provides adequate amplitude, with minimum energy in each bit.  
         [0295]    Referring to FIGS.  44 - 47 , a burst generator  325  provides an alternative method and apparatus for reducing the transmitted energy per bit, while maintaining adequate SNR. In the embodiment illustrated in FIGS.  44 - 47 , energy transmitted is substantially decreased, the pulse width of a parent pulse may be maintained, and the SNR is substantially maintained.  
         [0296]    The signal conditioning provided by the burst generator  325  is “undone” by a combination of an integrator  326  and a subsequent Schmitt trigger  328 . The reconstructed output pulse signal  329  looks substantially identical to the input signal  332 . The effect of the burst generator  325  is to replace an electronic input  332  with a series of much shorter photonic “spikes” occurring pseudo-randomly within the time period of the original pulse of the signal  332 .  
         [0297]    The original pulse is converted into a signal best described as a series of pedestals or a series of bristles, each having a large void fraction in the time domain. A delay-domain multiplexer, in accordance with the invention, thereafter transmits the bristle-like signals, requiring substantially reduced energy per channel of information. The bristles may be converted back to electronic form by an electronic post processor  36 . The electronic version of the “bristle signals” is integrated by the integrator  326 , provided as a signal  327  (integrated output  327 ) to drive the Schmitt trigger  328 , which, in turn, produces the reconstituted output  329 .  
         [0298]    Referring to FIGS.  45 - 47 , while continuing to refer generally to FIGS.  1 - 44 , a pulse input  332 , characterized by a pulse  362  extending over a time interval  364  is provided as an input  332  into a pair of lasers  334   a ,  334   b  operate at frequencies that are close, but not identical. A tremendous advantage in this configuration for the laser  334  is that exact frequency matching is not required. Provision of two lasers  334  that are substantially close in frequency, but not identical is a relatively inexpensive proposition. Thus, a comparatively inexpensive burst generator  325  is possible.  
         [0299]    By contrast, in the art of laser design, a distinct tendency exists to seek longer coherence lengths, and higher precision and predictability in the output of lasers. Meanwhile, an apparatus in accordance with the present invention takes advantage of comparatively inexpensive lasers, to provide a distinct advantage in generating signals, a distinct improvement in the art.  
         [0300]    The lasers  334   a ,  334   b  produce beams  335   a ,  335   b , respectively, that are directed toward one another at a selected angle  336 . The angle  336  is exaggerated in the illustration, and may be selected to produce the desired effect of interference therebetween. Optional optical elements  338  may further condition the beams  335 . Nevertheless, with or without the optical elements  338 , the beams  335  are superpositioned to produce a Young&#39;s-type interference fringe. If the optional lenses  338  or other equivalent optical elements  338  are used, then an expanded beam  340  may result from each of the respective beams  335 .  
         [0301]    Nevertheless, by either mode, Young&#39;s-type interference occurs within an image region  342 . Within the image region  342 , a constructive interference point  344  moves continually in a lateral direction  346  across the interference region  342  in accordance with the “beat frequency” corresponding to the two frequencies associated with the respective lasers  334   a ,  334   b.    
         [0302]    The constructive interference point  344 , or constructive interference  344 , continues to sweep back across the region  342  defined by a width  343 . An aperture  350  is smaller than the width  343  of the interference region  342 . The aperture width  351  may correspond to an optional mask  348 , or a significant plane (e.g. diameter of cross-section) of an output fiber  352 . In either event, the ratio between the aperture width  351  and the width  343  of the interference region  342  defines a duty cycle of the individual spikes  354 . The result is a continual stream of spike pulses (bristle pulses)  354  as long as the pulse  362  remains on during the interval  364 .  
         [0303]    Each of the pulses  354  (see FIG. 47) maintains the desired SNR, yet contains substantially less energy than that contained in the original pulse  362  during the same corresponding time interval time period. Thus, all of the bristle pulses  354  together have less net energy during the time interval  364  than does the pulse  362 , while maintaining a high SNR.  
         [0304]    One may think of the bristle pulses  354  as having a period  356  determined by the beat frequency, resulting in an off time  358  therebetween. Just as the signal  332  contains a pulse  362 , the output signal  359  of the burst generator  325  contains a series of pulses  354  that are effectively “bursts” for bristle pulses  354 .  
         [0305]    The burst pulses  354  or bristle pulses  354  pass into the encoder  12 , and eventually through the decoder  14 , as the complementary outputs  108 ,  110 . The pulses  354  are then processed by the electronic post processor  36  to become the output signal  37 . The integrator  326  receives the signal  37  and produces the output signal  327  containing a wave form  365 . The wave form  365  remains above a trigger threshold  366  at all times during the time interval  364 .  
         [0306]    For example, each burst pulse  354  (e.g. pulse  354   a ) includes a rise portion  368  followed by a decay portion  370 . Immediately thereafter, the next burst pulse  354  (e.g. burst pulse  354   b  in the example) has a subsequent rise portion  368 B followed by a decayed portion  370   b . Accordingly, during the entire time period  364 , the value of the wave form  365  remains above of the trigger threshold  356 . This wave form  365  of the signal  327  drives a Schmitt trigger  328 .  
         [0307]    Referring to FIG. 47, the Schmitt trigger  328  of FIG. 46 triggers at the threshold value  366  producing an output signal  329 . The output signal  329  is characterized by a reconstructed pulse  372  extending over substantially the same time interval  364 . In reality, due to the shape of the wave form  365 , and the operation of the Schmitt trigger  328 , the actual time interval  374  may differ slightly from the original time interval  364 . Nevertheless, all the digital information contained in the original pulse  362  is reconstituted in the output pulse  374  from the Schmitt trigger  328 . Thus, all the information included in the signal  332  is contained in the output signal  329 .  
         [0308]    The apparatus of FIG. 46 illustrates an alternative embodiment of a burst generator  325 . In the embodiment of FIG. 46, the lasers  334  may operate identically to those of FIG. 45. Nevertheless, rather than relying on masking or separation by virtue of an aperture in a mask or an aperture of a single output fiber, the constructive interference point  344  is permitted to sweep across a plurality of output fibers  352 , thus creating a plurality of sequenced burst pulses  354  sequentially in those fibers  352 . Each fiber  352  may be thought of as a single aperture accessed in sequence. The signals in each of the output fibers  354   a ,  354   b ,  354   c ,  354   d  may be subsequently modulated with their own unique information as multiple, sequenced channels. A photonic, time-division multiplexing operation may be thus conducted. This embodiment also exhibits the dispersive advantages of pulse  238  of FIG. 29.  
         [0309]    Referring to FIGS.  48 - 50 , an apparatus  410  may receive an input signal  414  into a modulator  412 . The modulator may pass a modulated signal  416  into a preconditioning modulator  418 . The function of the preconditioning modulator is to continually vary the value of a parameter used for modulation, in order to provide a preconditioned signal  420  into a delay-domain encoder  12 . The preconditioning of the signal  416  assures that a leading daughter signal  419   a  associated with one daughter pair  419  (e.g.  419   a ,  419   b ), will not provide coherence coincidence with a trailing daughter signal  421   b  from a preceding daughter pair  421  (e.g. signals  421   a ,  421   b ).  
         [0310]    The transmission medium  30  carries the signals  419 ,  421  to a delay-domain decoder  14  for de-multiplexing. Thereafter the information can be retrieved by demodulation in the demodulator  422 . The purpose of the modulation in the preconditioning modulator  418  is accomplished by the mere avoidance of accidental coherence coincidence, and thus no corresponding demodulation is required. Also, the multiplexing and demultiplexing are independent from the modulation of the original modulator  412  embodying the information in the signal  416 .  
         [0311]    The input signal  414  may be any suitable analog or digital signal, including a legacy signal from a fiberoptic system, or a conversion of an electronic signal to a photonic signal. In one presently preferred embodiment, the input signal  414  is modulated in any suitable domain, including modulation in multiple domains. Modulation for embedding information may be compounded by modulation for preconditioning.  
         [0312]    Domains for pre-conditioning modulation, may include, for example, amplitude, frequency, phase, and polarization. The pre-conditioning modulator  418  may include a splitter  426  that passes one signal along a path  428  directly, and another signal into a modulator  430 . In certain embodiments, modulation may be accomplished by a Mach-Zehnder phase modulator  430  driven beyond the typical 180 degrees of phase shift, in order to produce frequency modulation. Experiments have shown that this phase modulation technique to produce frequency modulation produces the desired result.  
         [0313]    In certain embodiments, the modulator  418  may include a splitter  426  selected to split based on amplitude or another suitable domain. A phase modulator  430  may be configured to continually alter the input signal  416  to produce frequency modulation at varying values of frequency. The preconditioned signal passes through the path  434  to the combiner  432 . Meanwhile, the direct signal passes through the bypass path  428  to the combiner  424 . The splitter  426  and combiner  432  may be solid, fiber, or free-space devices.  
         [0314]    Thus, in certain embodiments, an original input signal  414  may be modulated in a first domain, and then modulated in a second domain to provide compound modulation. The domains may preferably be different. Domains may include amplitude, frequency, and polarization. The compound-modulated input signal  420  may, after this preconditioning, be launched into a delay-domain encoder  12  for multiplexing.  
         [0315]    At any given instant of time, a signal  426  may be propagated at a frequency  438  as illustrated in FIG. 50. A conventional or legacy signal  414 ,  416 , modulated (e.g. FM) to a signal  420  with its new protection against accidental coherence coincidence between disparate information, may be launched into a delay-domain encoder  12  for splitting into daughter signals  48 , 419 , 421  as discussed earlier. An amplitude  440 , plotted against a frequency  438  illustrates an embodiment of a direct daughter signal  442 , and a delayed daughter signal  444 .  
         [0316]    By the time a delayed daughter signal  428  is ready to be re-combined, a parametric value (e.g. a frequency) of a direct signal from a subsequent wave form  412  has moved slightly off the nominal value of the preconditioning-modulation-domain parameter (e.g. frequency) in the compound modulation, preconditioning domain. Due to the shift, No interference can occur between the trailing (delayed) daughter  444  of a first set of daughter signals and the leading (direct) daughter  442  of the subsequent set of daughter signals. Thus cross-talk due to accidental interference (coherence coincidence) may be greatly reduced.  
         [0317]    Time delays used for multiplexing in a delay domain may be selected for optimum performance. The domain and the drift or continual shifting in the value of a modulated parameter in a preconditioning domain can be selected to operate in tandem (compounding) with another modulation domain relied upon to encode information. By coordinating, for example, a frequency in a frequency modulation of a signal, with the delay used in a delay-domain encoder of a delay-domain multiplexing system, accidental coherent coincidence may be avoided.  
         [0318]    The present invention may be embodied in other specific forms without departing from its structures, methods, or other essential characteristics as broadly described herein and claimed hereinafter. The described embodiments are to be considered in all respects only as illustrative, and not restrictive. The scope of the invention is, therefore, indicated by the appended claims, rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims are to be embraced within their scope.