Optical autodiscovery for automated logical and physical connectivity check between optical modules

Optical autodiscovery is provide between two optical modules to insure that when an optical signal is coupled between the two optical module, the optical signal from a first module does not interfere with operation of a second module. The autodiscovery is implemented by sending an optical identification signal from the first optical module via the coupling to the second optical module from which signal, the second optical module can verify and determined acceptance of the coupled first optical module. During this autodiscovery process, the optical identification signal from the first optical module may be attenuated or shifted in optical spectrum so as not to interfere with the operation of the second optical module. Autodiscovery may also be employed in cases where a first optical module is to receive an optical signal from a second module.

INVENTORY OF TERMINOLOGY TERMS

BMM—Band Multiplexer Module. There may be one for C Band and one for the L Band.

Channels—A signal channel that minimally includes a modulated source. The channel may be in discrete form or in integrated form. In integrated form in a TxPIC, there is a plurality of modulated signal channels each having a modulated source of different emission wavelength. The outputs of the signal channels are coupled to an integrated combiner which provides a combined output signal of the channel signals.

DLM—Digital Line Module. A substantially line side module that includes a PIC module having a TxPIC and RxPIC.

EMS—Element management system basically comprising software to operate a management and control module (MCM).

MCM—Management and Control Module is responsible for operating network elements (NEs) and the communication between network elements.

Modulated sources—With reference to a TxPIC comprises a modulated semiconductor laser or a continuous wave (cw) laser integrated with an external modulator. The laser may be, for example, a distributed feedback (DFB) laser or a distributed Bragg reflector (DBR) laser. Examples of an external modulator are electro-absorption modulator (EAM) or a Mach-Zehnder modulator (MZM).

NE—Network element in an optical transport or transmission network.

OCG—Optical Channel Group. OCG has particular reference to the group of combined or multiplexed channel signals at the output of a TxPIC.

OSC—Optical supervisory channel for optical signals that provide, as one example, communication between network elements.

PIC—Photonic Integrated Circuit. A plurality of optical elements integrated on a single semiconductor substrate, such as a Group III-V substrate, e.g., InP substrate, or on a polymer substrate. A planar lightwave circuit (PLC) is sometimes referenced as a PIC but a PLC generally has reference to a plurality of optical active and/or passive elements that are aligned and/or butt joined together in an optical communal relationship.

RxPIC—Receiver Photonic Integrated Circuit. The circuit comprises a circuit-integrated demultiplexer with a plurality of outputs to an integrated array of photodetectors (PDs).

TxPIC—Transmitter Photonic Integrated Circuit. The circuit comprises a plurality of integrated signal channels with inputs provided to a circuit-integrated multiplexer.

WDM—Wavelength Division Multiplexing—Concurrent transmission of optical data on a plurality of different wavelengths in a given direction. WDM herein is intended to include dense wavelength division multiplexing (DWDM).

BACKGROUND OF THE INVENTION

This invention relates to autodiscovery relative to optical network modules and more particularly to optical autodiscovery between two optical or electro-optical modules employed in a network element of an optical transmission network.

In optical transmission equipment, many equipment manufacturers or vendors authenticate card placement in the equipment chassis by electronically monitoring via the overall network manager or element management system (EMS) in the equipment of network element. EMS is software that manages the network element (NE), which software here is what we refer to as network management software in a management and control module (MCM). It is known in such equipment to apply electronic autodiscovery to determine if a module card has been place in the correct slot in the equipment chassis in a network element and/or if the module card is electrically working properly. However, the technique of electronic monitoring does not and cannot provide a guarantee that the optical paths connecting optical module line cards or optical modules, for example, have been properly connected by a technician or operator upon their installation. A typical optical line side network card in an optical transceiver provides for optical signal generation and optical signal reception of optical client signals from an optical transmission link. These optical client signals are generally generated on the line card side of the transmission equipment but can also be generated on the client or customer-connected side of the network element equipment as well. We refer to the optical modules that includes these optical transmitters and optical receivers as a digital line module (DLM) which includes a plurality of optical signal channels each designed to respectively generate or receive an optical client signal where the optical signals are of different wavelengths so that these signals are then combined and decombined, as the case may be, such as via wavelength division multiplexing (WDM). When a set of optical channel signals from a plurality of signal channels are combined, such as via optical multiplexing, we call the resultant WDM signal an optical channel group (OCG).

The lack of the aforementioned optical module connectivity guarantee is a particular problem where an optical module is improperly connected to another optical module port via an optical cable or fiber in network element equipment chassis. For example, the connected optical module may include another OCG that contains channel signals, for example, that are already present in another optical module that has been previously connected or provisioned in the network element equipment. There are many optical connectors and ports on the front of the equipment chassis and it is not uncommon for the technician to incorrectly interconnect an optical cable, which is also referred to in this disclosure as optical patching, between optical modules. Such incorrect optical cabling or patching is not electronically detectable. Such an incorrect optical connection between first and second optical modules may result in incapacitating other provisioned and working optical signal channels through coherent crosstalk, particularly if one or more of the signal wavelengths of the incorrectly first optical module are identical with one of the signal wavelengths already installed or provisioned to the second optical module. If the error is not detected in advance of optical patching of such incorrect optical patching, the ongoing traffic through the second optical module will be corrupted.

What is needed is some way of optical detection signaling, such as optical autodiscovery, to check for proper optical connectivity, or the lack thereof, which would add significant benefit in booting up WDM network element equipment or permit the network to continually operate without impairment when adding a new optical module into equipment chassis at a network element.

SUMMARY OF THE INVENTION

According to this disclosure, optical autodiscovery is provided between two optical modules where if an optical output signal from a first optical module, such output signal comprising, for example, an information modulated signal, is coupled through a module port of a second optical module, such as via an optical patching. The optical output signal from the first optical module is initially attenuated or its wavelength or wavelength bandwidth is spectrally shifted until the second optical module is able to authenticate that the first optical module is a proper module for connection to the second optical module via a second module port. How this authentication is accomplished is explained below. The attenuation can be applied by an element either at the first optical module or the second optical module or a combination of both modules. In the embodiments shown here, attenuation or wavelength or wavelength band shifting is illustrated as initiated in the first optical module. If the identity of the first optical module is confirmed as proper, then the first optical module receives an acceptance from the second optical module and the first module is allowed to remove the attenuation from its output signal or spectrally re-shift the its wavelength or wavelength bandwidth to its proper spectral position, as the case may be. In the case of attenuation, therefore, a full power output signal is allowed to be provided to the second module port. We refer in this disclosure to the first optical module as an “aggressor” module and we refer to any previously connected or patched optical modules to the second optical module as a “victim” or “victims”.

There are three primary situations where authentication between first and second optical modules is desired. First, connecting a first optical module to an incorrect port of a second optical module. Second, connecting a first optical module to an incorrect second optical module or vice versa. Third, connecting a first optical module of a first product generation to a second and incorrect optical module of a second product generation or vice versa.

In the first situation, there are two possible scenarios. In the first scenario, a first optical module is patched to an incorrect port of a second optical module where the second optical module is correct for the first optical module. The autodiscovery provisioning in this scenario is called pre-provisioning where the second optical module expects to find the first optical module patched at a particular port of the second optical module. In the second scenario, the first optical module is “correct” for a given module port of the second optical module but is still incorrect because another first optical module has already be provisioned for that given port through previous autodiscovery with that particular earlier provisioned first optical module. The autodiscovery provisioning in this scenario is called auto-creation which allows any first optical module of a first predetermined optical signal or optical channel group (OCG) signal to be provisioned to a predetermined port of the second optical module. However, once an appropriate first optical module has been associated with the predetermined port of the second optical module, then, the second optical module will not accept any other first optical module into that port even if another such first optical module has the same optical signal type or OCG signal type. This second scenario prevents the situation from occurring where, for example, during equipment chassis replacement, the placement or patching of the incorrect first optical module, having a first predetermined optical signal or OCG signal and a first module superimposed first ID signal, with an incorrect second optical module that already previously provisioned an identical first optical module with a first module superimposed second ID signal having the same first predetermined optical signal or OCG signal. In exemplary examples in this disclosure, reference will be primarily made to the first situation. However, it should be realized that the second and third situations are equally applicable to the principals explained in this disclosure.

It should be realized, at this point, that the identify of the first optical module is usually accomplished by module identification rather than by optical signal or OCG signal identification, or by both module identification and optical signal or OCG signal identification. However, the principals of this disclosure can be equally extended to identification through optical signal or OCG signal identification rather than a particular first module.

Also, the principals of this disclosure can be extended to the identification as to a proper optical module connection may be the identification of the second optical module by the first optical module where the first module identifies the second module as an incorrect second optical module. This is particularly true in the case where the first optical module not only transmits, via patching, an optical signal or an OCG signal to the second optical module, but also in the second optical module transmits, via patching, an optical signal or an OCG signal to the second optical module that are proper for that module. Such a particular case is where the first optical module is an optical transceiver. However, the need of identification of the second optical module by the first optical module can be resolved by employing a duplex fiber connection for patching which allows checking for proper module identification in only one transmit direction between the first and second optical modules under the assumption that the other or opposite transmit direction is the same for the dual fiber port at the second optical module.

The identity of the first optical module may come from the first module to the second optical module and may be in the form of an additional modulated signal superimposed on the first module optical output signal, whether a single optical signal or an OCG signal, with a modulation frequency that is spectrally different from any other data modulation signals appearing on the first module optical output signal. Alternatively, the optical signal identifying the first optical module may be in the form of a separate modulated identification optical signal added to (such as multiplexed) or separate from the first module optical output signal. The first module output signal may further be a plurality of modulated signals, e.g., an optical channel group (OCG) WDM signal of a plurality of optical channel signals from a plurality of optical modulated sources, or may be a plurality of different optical channel group (OCG) signals combined or interleaved together at the first optical module.

Optical signal identification of the first optical module is provided through the optical fiber connection or optical cable to the second optical module, which connection is also referred to as optical patching, between, for example, an optical first module comprising an optical channel group (OCG) transceiver or a group of OCG transceivers in a digital line module (DLM) and a companion optical second module called a band MUX/DEMUX module (BMM), for banding and disbanding such optical channel groups (OCGs) from one another. The connectivity check of this disclosure provides a DLM/BMM authentication process which is accomplished without harming other operating optical signal channels in other optical channel groups (OCGs) already coupled, authenticated and provisioned from a DLM to a BMM if, indeed, the DLM/BMM connection that is to be patched turns out to be an improper optical patched connection.

This invention, therefore, can be utilized as an optical autodiscovery technique in any situation where two optical modules are being coupled together in any optical transmission system, including, but not limited to, optical transport networks or local area networks, particularly where there is a danger of causing faulty operation to optical signals already coupled or provisioned between two such modules.

DETAILED DESCRIPTION OF DISCLOSURE EMBODIMENTS

Before delving into the optical autodiscovery embodiments of this disclosure, an explanation of the exemplary modules in the implementation of the disclosed embodiments should be first explained. Reference is first made toFIG. 1which discloses a photonic integrated circuit (PIC) group designated as PIC module A. PIC module A comprises a chip set of two PIC chips. Although the chip circuits could, alternatively, be integrated on a single chip. The transmitter PIC or TxPIC chip10contains a group of optical signal channels (1) to (N) where each channel15minimally includes a laser14and an electro-optical modulator (EOM)16. The lasers (1) . . . (N) may each have an associated heater13which is control via a wavelength locker (not shown) to maintain a peak wavelength forming a wavelength grid of signal channels15across the channel array of TxPIC10. Each channel15may include additional electro-optic elements, such as shown here comprising back and front monitoring photodetectors (PDs)12and18. The modulated signal output from each optical channel15in TxPIC10is combined via MUX20into a WDM signal referred to as an optical channel group (OCG) providing a WDM output OCG(A) signal at21which is then provided to an output cable26A (FIG. 2A). MUX20may be an arrayed waveguide grating (AWG) or an Echelle grating, but also can be a free space coupler or a multi-mode interference (MMI) coupler. Further details of TxPIC10can be seen in published Application No. US 2003/0095737 A1, published on May 22, 2003, which is U.S. nonprovisional patent application, Ser. No. 10/267,331, filed on Oct. 8, 2002, which application is incorporated herein by its reference.

An important aspect of this disclosure is that the OCG output signal at26A from the multiplexer20, as shown inFIG. 1, passes through an optical signal attenuator, shown here as a variable optical attenuator (VOA)22. Also, a low frequency modulator (LF MOD)24is coupled to attenuator22to modulate any output at26A with a communication signal to be provided to BMM40. With reference toFIG. 2A, attenuator22is employed in conjunction with optical autodiscovery to initially attenuate OCG(A) signal on cable26A when cabled to a BMM port42A so as not to optical interfere with other previously connected OCG signals, such as, for example, OCG(B), OCG(C) or OCG(D), already optically patched to band multiplexer module (BMM)40already optically patched to other digital line modules or DLM (B), DLM (C) or DLM (D), respectively, via other BMM input/output ports42B,42C or42D, until such a cabled OCG signal, here, the OCG(A) signal on cable26A, is, first, authenticated as a proper combined signal to be optically coupled to a particular BMM input/output port42. For example, improper optical patching or cabling of a TxPIC output OCG signal from its corresponding DLM with at least one signal wavelength substantially identical to a signal wavelength of already provisioned within an OCG signal from another DLM, previously, optically patched to BMM40, would wash out those identical wavelength signals. Therefore, it is important to make sure that identical spectral signals are not accidentally provided to the same BMM40which has the function combining together the plural OCGs.

The PIC output VOA22may be integrated on the same semiconductor substrate as all the other integrated elements12,14,16,18and20of TxPIC10or it may be a separate optical component, such as a MEMs VOA, optically coupled to receive the OCG output at21. Also, as indicated above, the OCG signal in TxPIC VOA20may be modulated with a low frequency signal (LF) from low frequency modulator (LF MOD)24indicative of the identity or ID tag of a particular DLM17and a particular OCG. This LF signal is also provide for signal communication from a DLM17containing PIC module (A) and BMM40to authenticate that this particular DLM17is the proper module for connection to a particular BMM input/output port42. In this connection, the important point here in understanding the deployment of this attenuation functionality is that the communication via a low intensity modulated signal from VOA22of an aggressor DLM to be connected is sufficiently low in power that it will not optically interfere with other optical signals from one or more other victim DLMs already provisioned into the BMM, even though the victim DLMs may possible include at least one signal wavelength that is identical to signal wavelength in the DLM to be connected. This is because the attenuated signal intensity from the aggressor DLM17is too low to conflict with any victim DLM17that has an OCG that includes at least one channel signal identical with that of the aggressor DLM17.

It will be realized by those skilled in the art that this low frequency identification (ID) signal can be superimposed on optical signals elsewhere in TxPIC10or within the DLM17. For example, the low frequency ID signal may be superimposed on one or more lasers14or on a photodetector18of TxPIC10, either as positioned in a signal channel15or, alternatively, provided by a separated but integrated light source on TxPIC10, or from a source separate from and outside of the integrated TxPIC10. Furthermore, the coupling of an unauthenticated OCG signal into a particular BMM input/output port42could, as previously indicated, be disastrous to previously provisioned OCG signals in continuous communication with BMM40.

Returning now toFIG. 1, PIC module (A) also includes a receiver PIC or RxPIC chip30comprising an input for OCG (A) signal optically patched from BMM40via cable26A to a decombiner32where the OCG input signal is optically demultiplexed into individual channel signals which are, respectively, converted into electrical signals by an array of integrated photodetectors (1) . . . (N) at34. Details of RxPIC30can be seen in published Application No. US 2004/0033004 A1, published on Feb. 19, 2004, which is U.S. nonprovisional patent application, Ser. No. 10/267,304, filed on Oct. 8, 2002, which application is incorporated herein by its reference.

Also, illustrated inFIG. 1is PIC digital signal processor (DSP) controller36which includes a digital processor or CPU36A. Controller36not only controls functionality on TxPIC10and RxPIC30but also controls the TxPIC laser wavelength locking and power control and maintains this optical circuit at their operating states. This control is maintained in spite of the fact that output VOA22of the DLM (A) ofFIG. 2may have been attenuated to a low intensity level to protect BMM40from potential optical interference with other OCG signals already provisioned to BMM40.

Reference is again made toFIG. 2Awhich shows additional DLMs, to wit, DLM (B), (C) and (D) with their respective WDM OCG signals OCG (B), OCG (C), and OCG (D) patched to respective BMM ports42B,42C, and42D of four port BMM40. Each DLM17has a respective output attenuator or VOA22. These four DLM output VOAs22, as a group, perform three functions. First, they are deployed to provide power balancing among the output OCG signals across several DLMs17which is basically a power balance of the average power between or among a plurality of DLMs. This is the subject matter of copending patent application, Ser. No. 11/425,988, filed Jun. 20, 2006, which is owned by the common assignee herein and is incorporated herein in its entirety by its reference. Second, VOAs22provide compensation over life in changes to the total DLM output from its respective TxPIC due to aging, for example, among other changing PIC parameters. In this regard, each signal channel on TxPIC10may also include an integrated VOA in each channel15(not shown) so that the power levels across the N channel signals of the PIC can be equalized. Third, VOAs22are employed for provisioning of DLMs17to BMM40by having their optical outputs initially attenuated and then modulated via LF MOD24to provide a low intensity communication that includes data identifying the DLM and its OCG and permitting BMM40to check with other resources to determined if a particular DLM17is the proper one to be provisioned for patching to BMM40at a particular BMM port42.

Thus, each DLM17, when patched to BMM40, as shown inFIG. 2A, undergoes this provisioning process with their attenuated output OCG signal at26modulated, via VOA22, in order to communicate directly with DSP controller40A in BMM40via a low frequency modulated signal to initiate and complete an autodiscovery authentication process. After authentication has been confirmed, the output power from DLM17is increased to its desired higher operating level by removing at least some of the power suppression on the DLM output OCG signal which is done by reducing the applied negative bias to output VOA22. Not all the bias is removed because some bias level may be maintained to insure that all DLM OCG outputs are power balance or have equalized power levels prior to OCG signal transfer to BMM40. The provisioned DLM signal is then received in BMM40and multiplexed at N:1 MUX48with other OCG signals from other cabled DLMs17. The power balancing can be accomplished with the use of taps44where a part of the input to BBM40is tapped and detected by photodetectors46for power level evaluation as well as signal communication with the DSP controller63(seeFIG. 3) for autodiscovery. It should be noted that the bandwidth response of photodetectors46does not include the data or client frequency signals of the OCG signal from DLM17which are in the GHz range but rather are only responsive to the lower frequency modulation of the modulated identification signal that is superimposed on the OCG signal.

Reference is now made toFIG. 2B, which discloses another embodiment of a DLM50which includes a plurality of PIC modules comprising PIC module (A), PIC module (B), PIC module (C), and PIC module (D), where each of the PIC modules are similar to PIC module (A) shown inFIG. 1. Each PIC module has its own attenuator22, designated respectively as VOA1, VOA2, VOA3, and VOA4on their respective PIC module outputs21, and provide their respective outputs OCG (A), (B), (C), and (D) signals via its output VOA22are provided on output lines26A to interleaver52. Interleaver52interleaves the OCG signals from the four PIC modules into a single output signal provided on interleaver output53. The combined interleaved output from interleaver52is provided to a DLM attenuator59that is optically coupled to low frequency (LF) signal modulator (MOD)57. Thus, the interleaved signal output is provided on output line50A as an OSG (1) signal via a patch cable to BMM60(FIG. 3).

Also, there is an OCG (1) signal input from the patch cable patched to BMM port62A to input line50B of DLM50to its deinterleaver51. The transport signals from BBM60that are proper for OSG (1) and respective PIC modules, PIC module (A), PIC module (B), PIC module (C), and PIC module (D) are received via line50B at deinterleaver51where they are deinterleaved as signal groups OCG (A), OCG (B), OCG (C), and OCG (D) and provided to respective PIC modules (A), (B), (C), and (D), via PIC input lines28A, in the same manner indicated inFIG. 1with respect to PIC Module (A) at RxPIC30.

Thus, the digital line module (DLM)50which includes PIC Group A OCG (A) fromFIG. 1now, as well, includes three other such signal groups OCG (B), OCG (C), and OCG (D). These channel groups are also connected to operational electronics indicated as electrical signal processing at54which, in turn, is connected to electronic cross-connection switch56. Switch56may be also connected to the electrical signal processing on one side and may be, as well, connected to other corresponding DLMs, or to optical tributaries (also called tributary adapter modules or TAMs which are not shown here) for connection to client signal transport equipment to receive from and send to client signals for transport or reception, respectively.

DLM50also includes PIC control electronics55to operate and to control the integrated electro-optic elements on the PICs in the PIC modules as well as provide wavelength locking of the lasers to predetermined peak emission wavelengths in each TxPIC. More detail of a DLM like DLM17can be seen in U.S. nonprovisional patent application, Ser. No. 11/154,455, filed Jun. 16, 2005, which application is incorporated herein by its reference. Also, more details concerning PIC control, such as for wavelength locking including PIC control, can be seen in published application No. 2003/0095736, published on May 22, 2003, which is U.S. nonprovisional patent application, Ser. No. 10/267,330, filed Oct. 8, 2002, and in U.S. nonprovisional patent application, Ser. No. 11/427,624, filed Jun. 29, 2006, all of which applications are incorporated herein by their reference. Also, DLM50inFIG. 2Bcontains a DLM DSP controller58, similar to DSP controller19inFIG. 1A, to control various functioning on the module as well as participate in optical autodiscovery which will be discussed later on. It should be noted that the same electronics diagrammatically illustrated here may also employed, in part, in the embodiment ofFIG. 2A.

It should be noted that it is within the scope of this invention that the PIC modules (A), (B), (C) and (D) each have a VOA, as previously mentioned in connection with PIC module A inFIG. 1, with a low frequency DLM ID signal applied via low frequency modulator (LF MOD)24to modulate the OCG signal from each respective PIC module passing through a respective VOA1, VOA2, VOA3and VOA4. The modulated signal is the same low frequency modulation provided on all DLMs17via modulator24and the signal bits represent an optical ID identification signal, identifying the DLM and its signal group, which is transmitted to a BMM60. However, as shown inFIG. 2B, all of the output OCG signals OCG (A), OCG (B), OCG (C), and OCG (D), respectively, from PIC module (A), PIC module (B), PIC module (C) and PIC module (D) are interleaved or otherwise multiplexed together to form a combined OCG (1) signal for patching, for example, to OCG input/output port62A of BMM60, as seen inFIG. 3. Thus, a common VOA59may be provided at the output of interleaver52for low attenuated signal communication between DLM50and BMM60in accordance with the teachings of this disclosure. However, the four VOAs22are still needed with the PIC modules (A), (B), (C) and (D) for output OCG signal power equalization across the PIC module array, which is the subject of Ser. No. (P076), supra.

Further, it is within the scope of this disclosure as another embodiment to employ one of the VOAs22of a single PIC module (A)-(D) inFIG. 2Bto provide for the low attenuated signed communication directly with BMM60on behalf of all OCG signals in DLM50where, in such a case, the other VOAs of these other OCG signals in DLM50would have their output OCG signals reduced to a negligible level during startup so as not to interfere with the communicating VOA22during the DLM/BMM authentication process. Thus, in this embodiment, VOA59would not be required for autodiscovery.

With reference to the DLM modules17ofFIG. 1AorFIG. 3, optical autodiscovery is provided as a way to check the optical connectivity between optical line side cards comprising DLM (A), DLM (B), DLM (C), and DLM (D) for physical and logical correctness, which may be circuit board cards in same equipment chassis or circuit board cards in different chassis. Such as circuit board card may be comprised of a digital line module (DLM), such as DLM17or DLM50, as previously discussed, and an interleaving or banding/disbanding card where groups of multiplexed or WDM signal groups, e.g., OCG (A), (B), (C), and OCG (D) signals, are interleaved or banded to form a resultant banded WDM signal or are deinterleaved or disbanded into WDM signal groups, i.e., OCG signal bands. Optical autodiscovery further provides a method by which the correct optical patching of the optical channel group (OCG) between a DLM17/50and a BBM60can be verified for physical as well as optical/electrical circuit logical correctness. Optical patching means optical connection of an OCG from a DLM50to BMM60which is usually handled by an optical cable with its end connectors plugged between these two optical modules.

Reference is now made toFIG. 3which illustrates further details of the band MUX/DEMUX module (BMM)60. In the following descriptions well as later description, reference is made to DLMs17as optically patched to BMM60. However, it should be understood that DLMs17with DSP controllers19may be a plurality of different DLMs50, each with multiple PIC modules and a DSP controller58, optically patched to the several input/output ports42/62of BMM40/60are basically the same except that more detail is shown for BMM60. Thus, it is to be importantly noted that DLMs17with DSPCs19in FIG.3alternatively may be a perspective DLM50with DSP controller58illustrated inFIG. 2Bwhere each provide a plurality of OCG signals combined, respectively, as OCG (1), . . . , and OCG(n), with n=4, which are respectively provided to respective BMM ports62A,62B,62C, and62D. However, as it would be understood by those skilled in the art, n may be any other number, within reason, such as, for example, n=8 or 10. Also, it should be noted that reference to DLMs17with DSPCs19inFIG. 3alternatively should be taken to alternatively also mean DLMs50with DSP controller58illustrated inFIG. 2B.

As seen inFIG. 3, the PIC OCG signals OCG (1), OCG (2), OCG (3), and OCG (4) from DLMs17are, respectively, patched to BBM input/output ports62A,62B,62C and62D. Thus, OCG (A) signal from DLM17ofFIG. 2Ais shown patched to BBM port62A. The same is true for other DLMs17, which are, respectively, patched to BMM ports62B,62C, and62D for coupling of combined channel signals OCG (B), OCG (C), and OCG (D) to BMM60. A small portion of the inputted OCG signals are tapped at photodetectors (PDs)61which PDs have a bandwidth to recover the autodiscovery signaling provided by discovery signaling from a modulated light source from a respective DLM17such as via its respective modulated VOA22. The optical-to-electrical discovery signals are received at the BMM DSP controller63. It should be noted that the bandwidth response of photodetectors61does not include the data or client frequency signals of the OCG signal from the DLM17which are in the GHz range but rather are only responsive to the lower frequency modulation of the modulated identification signal that is superimposed on the OCG signal.

Thus, for example, if an aggressor DLM (C) is patched to BMM input/output port62C, a modulated signal from its respective output VOA22may be received at BMM60via photodetector61C that identifies the DLM and its OCG signal. The BMM DSP controller63may contain information in memory as to what DLM and optical channel group (OCG) is proper for its particular input/output port62C. If a different DLM17than the DLM and OCG signal expected is patched to port62C, then BMM60will reject it as explained in further detail later on. The other signal taps91A,91B,91C, and91D are for monitoring input power of the respective DLMs17after autodiscovery has been achieved where the input power levels of OCG (1), OCG (2), OCG (3), and OCG (4) are substantially made equal to one another via operation of their respective output attenuators, such as VOAs22inFIG. 2A, as discussed in patent application, Ser. No. 11/425,988, filed Jun. 20, 2006, supra.

On ingress of BMM60, OCG (n) pairs, such as alternate pairs OCG (1) and OCG (3); and OCG (2) and OCG (4), respectively, are banded together via input band multiplexers64A and64B. Thus, two band MUXs64A and64B provide together two OCG interleaved signals. In this way, the groups of channel wavelengths are banded together as a banded signal. Then, the two banded signals from band MUXs64A and64B are multiplexed together at a 2:1 multiplexer66and passed through a band booster amplifier68, e.g. EDFA or other optical amplifier. An optical service channel or optical supervisory channel (OSC) signal may, then, be added to the amplified signal via OSC filter70, which multiplexes the OSC signal from OSC transmitter71to the amplified combined and banded signal from amplifier68. OSC transmitter71is in communication with BMM control processor63. Other banded signals from other wavelength bands, such as, for example, from the L band if, for example, BMM60here is a designed for C band signals, may be also added to the composite signal at C/L filter72. A 2% tap74provides an output to a monitoring photodetector (not shown). The banded signal is then provided to an optical link via BMM output76.

The receiver side of BMM60shown inFIG. 3generally contains some similar optical components as the transmitter side except that they are, of course, operative in a reverse mode. A banded composite signal at BMM input78from an optical link or line is received first by C/L filter80, via monitoring tap79(coupled to a photodetector which is not shown), where other signal bands, such as L band signals, if the BMM60ofFIG. 3is designed for the C band, are demultiplexed from the incoming composite signal. The remaining C band composite signal may then pass through an attenuator82to reduce the signal power level, if required, to a level where the downstream band booster amplifier86operates to provide optimum gain to the composite signal. Next, any OSC signal in the composite signal is demultplexed from the banded signals at OSC filter84and the OSC signal is received and detected at OSC receiver85. OSC RX85is in communication with BMM control processor63. After the banded signal is amplified by band booster amplifier86, e.g., an EDFA, the DLM banded composite signal is disbanded at deinterleaver85into two OCG banded signals. The disbanded signals are then demultiplexed at band DEMUXs90A and90B into OCG signal pairs, OCG (A) and OCG (B), and OCG (C) and OCG (4D). The optical channel group (OCG) signals OCG (A), OCG (B), OCG (C), and OCG (D) are provided to their respective DLMs, i.e., DLM (A), DLM (B), DLM (C), and DLM (D) via BMM input/output ports62A,62B,62C, and62D, as shown patched in the embodiment ofFIG. 3.

BMM control processor63handles functions on the BMM board as well as plays a role in the optical autodiscovery procedure set forth below in more detail.

While there are many approaches to how the control and management can be accomplished among various modules and line cards making up network element equipment, the control methodology illustrated inFIG. 4may be followed as an example. Here, network element controller (NC)101in management and control module (MCM)100is in communication with the DSP controllers19in each of the electro-optic DLMs17and a BMM60at the network element. Also, there the element system management (ESM) which is the software that operates MCM100to coordinate control and communication functions among and between DLM DSP controller19and BMM DSP controller63via network element controller (NC)101of MCM100.

Optical autodiscovery provides the following protection against system fault conditions. First, for example, if a technician or operator optically cables or connects a second DLM17(the “aggressor”) to the incorrect BMM input/output port62, the second, aggressor DLM17OCG signal output is initially attenuated significantly so that its resultant output is sufficiently low in power so as not to be disruptive to an OCG signal of a first DLM (the “victim”) previously patched and provisioned to the same BMM60. Thus, optical auto discovery prevents an aggressor DLM17from possibly generating any coherent crosstalk with a patched and operating victim DLM17, particularly where the aggressor DLM17includes an OCG signal having at least one identical wavelength which already exists in a previously patched OCG signal of the victim DLM17.

Second, if the technician or operator optically patches an aggressor DLM17to a BMM60, whether to a correct BMM port62or not, and such a connection is in conflict with currently desired provisioning, then, again, the aggressor DLM OCG output is attenuated so that its resultant output is sufficiently low in power as not to be disruptive threat of any previously provisioned victim DLM OCG of a victim DLM OCG in the future. This prevents the aggressor DLM from being brought into service in a configuration that differs from that which was intended to be provisioned through MCM100and BMM60.

Thus, protection to an already provisioned DLM or DLMs17is achieved by attenuating the overall optical channel group (OCG) output power of an aggressor DLM17to be patched an provisioned to a BMM60, whether the aggressor DLM17is provisioned with one TxPIC module, as illustrated inFIG. 2A, or the aggressor DLM50is provisioned with multiple TxPIC modules, as illustrated inFIG. 2B. In either case, the OCG power output is attenuated to a non-destructive power level via VOA22or VOA59of these DLMs, as the case may be. Therefore, the attenuated output of the aggressor DLM17does not substantially interfere with already existing and another operational optical channel group (OCG) of a victim DLM17previously patched to the same BMM60. The optical channel group (OCG) being patched includes an optical low frequency modulated ID signal, which is separated spectrally separated significantly from the OCG signal bandwidth of signals being transmitted. The low frequency signal is representative of an ID tag for the particular OCG signal and the signal is modulated with information identifying the DLM17as well as its particular OCG being ported to a particular BMM input/output port62. Thus, optical discovery process specifically identifies the particular transmitting, aggressor DLM being optically cabled to a particular BMM port62. This OCG signal ID tag is detected at BMM input/output port62via input photodetector63, and the resultant electrical signal is decoded at the BMM DSP controller63. In response to this signal, controller63provides either an acceptance signal to the aggressor DLM17via an electrical communication signal, either directly or via network element controller101or, on the other hand, raises an alarm to an operator that the aggressor DLM17is either an incorrect OCG signal group and DLM, or is patched to an incorrect BMM input/output port62. If the physical connectivity made is accepted by BMM60, then, as just indicated above, an acceptance is reported to the aggressor DLM17, which may be an electrical signal or return optical signal. Thus, if the detected DLM/BMM optical port association matches the pre-provisioned association in memory at BMM DSP controller63, or if auto-provisioning is enabled, the aggressor DLM17being patched to BMM60is then enabled by BMM DSP controller63for power output turned up from its initial lower, attenuated power level, which is accomplished through reduction of applied negative bias to DLM output VOA22, permitting a full power OCG signal output from the aggressor DLM. Therefore, DLM signal operation with BMM60is allowed to proceed by transmission of an OCG signal from the now accepted DLM which is no longer an “aggressor”. The foregoing procedure is explained in further detail later on with respect to the flow chart set forth inFIG. 6.

The respective BMM ports63are sequence through the operational states during optical autodiscovery illustrated in the state diagram ofFIG. 5.FIG. 5shows the DLM-to-BMM port state machine, which is maintained by DLM DSP controller19and BMM controller62. The state definitions are useful in understanding the operation of this disclosure but are not necessarily sequentially followed as shown inFIG. 5and all states shown are not necessarily included in an implementation of optical autodiscovery. However, these states, or their equivalents, must be maintained by DSP controller19because, in some cases, such states must persist through, for example, a PIC module processor (CPU)36A reboot process (FIG. 1). As shown, the signaling states can only be entered into when a DLM DSP controller19of an aggressor DLM17has provided a valid DLM ID to BMM60enabling autodiscovery. An autodiscovery initiation may first be started with a signal from DLM controller19to the PIC DSP Controller36after a DLM processor reboot for autodiscovery has been initiated to determine PIC module status. If the DLM DSP controller19detects that the PIC module processor36A in a “down” condition, it must first clear any existing enabled state.

The states inFIG. 5are described as follows:

INITIALIZATION—In this state, the TxPIC10in PIC module (A) has not yet completed stabilization, which is referred to as DLM TURNUP and, therefore, the module is not ready to be put into service. From the standpoint of this discussion, a “catastrophic” fault is one that prevents further turnup. It should be noted that all fault types do not necessarily prevent further turnup. For example, a subset of TxPIC lasers14on a TxPIC10may have failed but initialization is allowed to proceed because the remaining and operating TxPIC lasers14are wavelength locked and are operating within the correct power range. Such a fault prevents the DLM17from exiting the initialization state. During initialization, VOA22in DLM17is set to its lowest rated attenuation level. That level is dictated by being sufficiently high in its attenuation to prevent disruption of an existing transmitting or victim DLM but still sufficiently low in its attenuation so as to allow enough optical power to be coupled to the BMM so that BMM photodetectors61are bale to detect the optical signal provide via modulated VOAs22.

LIGHT BLOCKED—The TxPIC module (A) is fully initialized and is transmitting a modulated waveform at the correct (open OCG loop) power and (closed loop) wavelength. The VOA22or59at an aggressor DLM17output is set to the maximum rated attenuation level in this state, which level is one that will not provide an OCG signal to a BMM60that would optically interfere with previously patched and enabled DLMs.

SIGNALING—This state is the same as LIGHT ATTENUATED state except the aggressor DLM VOA22/59is being used to amplitude modulate the overall OCG signal with a DLM ID message, which is repetitively sent to BMM60. The DLM ID uniquely identifies the particular aggressor DLM17and its associated OCG signal output, such as, but not limited to, by its manufacturing serial number. The identification here is, therefore, of a serial number of a particular DLM which identifies to a second optical module, such as a BMM, that the connected or patched DLM is connected to the correct BMM. Such identification could include the particular OCG signal type, such as in the C band or the L band, but OCG identification can be determined by inspection via software to determine which OCG type is configured with respect to a particular DLM. It should be noted further that the identification to be made here is that of the particular DLM unit17, but it is also within the scope of this disclosure that the ID tags can be, respectively, provided for several different PIC modules (A), (B), (C), and/or (D) included in a single DLM50ofFIG. 2Bwith each having its own respective ID rather than one DLM ID tag representing a tag for all the PIC modules (A), (B), (C), and (D) associated with a particular DLM50.

WAIT FOR OGC SAMPLE—In this particular state, VOA22/59of the aggressor DLM17/50is set to a low attenuation level and is waiting for the event of a first OCG acceptance from BMM60.

NORMAL/ENABLED—In this state, BMM60has accepted the aggressor DLM17as legitimate and its VOA22in this state is set to its operational range and is employed via an OCG power control loop to set the OCG signal power at the respective BMM port62to normal full power condition by removing the attenuation of VOA22.

DISABLED—TxPIC lasers14are powered down and VOA22/59is set to a low attenuation level if a VOA timer has timed out. This is basically a “bottom” state of the state diagram ofFIG. 5.

TX SHUTDOWN—A critical fault has been detected that causes TxPIC10to be disabled, such as, for example, incorrect bias on laser heaters13on TxPIC10, incorrect bias current provided to TxPIC lasers14and/or a PIC thermoelectric controller (TEC) to control the temperature of TxPIC10(not shown) is not a correct setting.

In summary, therefore, if an aggressor DLM17is erroneously patched to an incorrect BMM port62, which BMM is already handing banded optical signals via other BMM ports62, optical interference may be incurred with other OCGs already provisioned through the other BMM input/output ports62if one or more OCG identical wavelengths of an aggressor DLM17are the same wavelengths in the provisioned OCGs. Since BMM60is provided with no mechanism for blocking an OCG input provided at a port62, the in-error OCG input from such an aggressor DLM50is first attenuated at the aggressor DLM17to an optical level, via DLM VOA22, that would fail to provide any possible optical interference with any provisioned OCG. Once there is verification by BMM60that the particular DLM port connection is correct and the OCG of the patched aggressor DLM17is deemed correct, the attenuation initially placed on the DLM OCG signal via DLM VOA22is lowered to permit the OCG output from the patched aggressor DLM to be placed at its normal operating optical signal level for input via its provisioned port62.

The autodiscovery sequence must be performed at a BMM port62whenever proper physical connectivity is in question. Such cases may be when either a BMM50or a DLM17is separated from the equipment chassis, or where DLM17or BMM60is power cycled or rebooted, or where DLM17or BMM60is power enabled for a first time and the BMM has detected a lack of clock synchronization, or where a technician or operator has manually called for a forced autodiscovery restart which is exemplified later inFIG. 6. After the autodiscovery signal is transmitted from a DLM17to a BMM60, via a BMM port62, transition to the NORMAL/ENABLED state may additionally require that the DLM/BMM association created by the optical cabled connection is provisioned with the aid of the management and control module (MCM)100. In this case, a DLM ID received by a BMM60via input photodetector61is verified at the BMM against a correct DLM ID held in MCM memory. However, the correct DLM ID may also, instead, be held in memory at BMM DSP controller63to be provisioned to a particular BMM, which DLM ID information, when required, is then downloaded to the BMM.

Successful completion of autodiscovery for DLM/BMM patching for transport of a given OCG DLM output requires that DLM DSP controller19, BMM DSP controller63and network element controller (NC)101are all active and executing operational software. Network element controller (NC)101can be on a different shelf in an equipment chassis so that it is coupled through backplane cables to BMM DSP controller63and DLM DSP controller19. The active network element controller (NC)101may be responsible for validating the received DLM ID at BMM60and then authorizing the transition to the NORMAL/ENABLED state inFIG. 5. A time window exists, such as one or more seconds, between the time BMM DSP controller63reports the received DLM ID and the time that DLM17turns up power across the channel laser array in TxPIC10and BMM60then enables the opening of BMM port62undergoing identification and acceptance. If an aggressor DLM17is erroneously plugged into a BMM port62on BMM60, signal power above a predetermined level will be detected and BMM DSP controller63will issue an alarm to a technician or operator. If BMM DSP controller63detects a loss of power condition at a BMM port62that is operating in the NORMAL state, then, the pre-existing DLM ID for that port will be invalidated and BMM60will inform MCM network element controller (NC)101of this condition which will then cause disablement of such an apparently now unconnected DLM.

An example of the sequence of events for autodiscovery activation relative to authentication occurring at MCM100rather than by BMM60through its own authentication processes is as follows. First, a DLM17is powered up and initialized. Second, a BMM40/60is powered up and initialized. Third, network element controller (NC)101is power up and initialized. Fourth, a desired DLM/BMM association is provisioned via the management software in MCM100. One type of provisioning is called pre-provisioning which is a key provisioned via the management software in MCM100as to what DLM is to be linked to what BMM and which DLM should be expected at one of its BMM ports62including the DLM OCG that it should expect. The other type of provisioning is called auto-creation, where neither the management software nor an operator performs the provisioning. Rather, a particular BMM port does not have any particular DLM identification associated with it but the BMM identifies an OCG type that will acceptable at a given BMM port. Thus, the BMM will accept any DLM at a given BMM port provided that the OCG type (a given C band group or L band group, for example) of the DLM matches the OCG type that the BMM expects at that given port. Once an acceptable OCG type of a patched DLM is present, no other DLM is permitted to be patched to that given port even if of the same OCG type. Of course, the same OCG would not be permitted at another BMM port of the same BMM. Fifth, the correct OCG cable from the aggressor DLM17is installed to the correct BMM DLM port62by an operator. Both the DLM and BMM DSP controllers19and63are booted and receive provisioning data via network element controller (NC)101from MCM100. Once both DLM17and BMM60are ready for autodiscovery, network element controller (NC)101directs DLM17to transmit its unique DLM ID via low frequency modulation from modulator24superimposed on its attenuated OCG signal at VOA22. It should be clear to those skilled in the art that all laser source channels need not necessarily be contributing to the OCG signal output during this low frequency ID signal modulation.

The DLM ID is then detected at a given BMM port62and received by BMM controller63. BMM DSP controller63then forwards the DLM ID to network element controller (NC)101. At MCM100, the BMM/DLM association based upon the received DLM ID is checked via a provisioning database that may be part of MCM100to determine if there is a correct association and match for BMM60with the aggressor DLM17. If provisioning is affirmative, then, network element controller101forwards to BMM DSP controller63the proper DLM address. This address then authenticates that the proper DLM has been associated with a proper BMM60. Then, BMM60provides a nominal value for the OCG signal power to the now accepted DLM17and the accepted DLM begins to transmit the DLM OCG signal at the proper power level in support of a per OCG power control procedure set forth in patent application, Ser. No. (P076), infra.

Upon any subsequent reboot of the DLM DSP controller19, no new exchange of authentication is necessary as long as DLM controller19is already in the NORMAL/ENABLED state inFIG. 5. If it is not, the DLM DSP controller19is directed to restart the initialization sequence again, at the conclusion of which the autodiscovery sequence. Since BMM60, at this point of time, will detect a loss-of-light condition at an associated BMM port62due to such an initiated DLM reboot, BMM DSP controller63will automatically invalidate the particular BMM port62and is ready to accept a new DLM ID address from the DLM upon its re-activation.

In the case of BMM DSP controller reboot, BMM DSP controller63checks for the occurrence of a loss-of-light condition on any one of the BMM ports62. If a loss-of-light condition is detected for a port, no action is necessary since the optical connectivity is known to have been preserved, i.e., if the condition of NORMAL/ENABLED existed at the time of BMM reboot, then that state is known to have persisted by BMM DSP controller63before its reboot. If the loss-of-light has occurred, BMM DSP controller63invalidates the DLM ID previously received by it and restarts an ID capture sequence while also notifying MCM100of this course of action. The MCM network element controller101, in turn, also informs the DLM17that was previously provisioned or is to be autoprovisioned now for the particular BMM port62and is directed to restart optical autodiscovery signaling procedure.

After BMM60successfully receives and accepts a DLM ID and DLM17is authorized to transition to NORMAL/ENABLED state, then a timer at BMM DSP controller63is commenced and if, during a predetermined time interval of the BMM timer, the maximum or high power level of the DLM OCG signal is not detected at the provisioned BMM port62, then, BMM controller63directs the DLM DSP controller19, such as through electrical signaling to the DLM17, to transition back to the SIGNALING state inFIG. 5and restart the autodiscovery sequence.

Another way of accomplishing optical autodiscovery is through the deployment of out-of-band wavelength signals to do the optical autodiscovery procedure. Such a different wavelength signal is separate from the DLM OCG signal group but may be multiplexed, for example, with the OCG signal. Since the separate ID signal is an out-of-band signal, it will not harm working or provisioned OCG signals previously provisioned to the BMM since the optical autodiscovery signal wavelength is out of the data signal bandwidth, such as the C band or L band, for example. These optical autodiscovery signals can alternatively be generated by an additional laser or on-chip laser or LED in a DLM17/50or on a TxPIC10. In the case of a laser, for example, its modulated “discovery” frequency for autodiscovery would not be in the frequency range of the data carrying optical frequencies of the OCGs. However, this approach employing separate optical signals may be more expensive than the embodiment discussed above relating to deploying low frequency modulated signal placed on an attenuated OCG signal from an aggressor DLM17to be patched to BMM60.

Reference is now made toFIG. 6which illustrates a flow diagram of the autodiscovery communication that occurs between DLM17and a BMM60. As seenFIG. 1, VOA22is couple to a low frequency modulator (LF MOD)24so that DLM DSP controller19provides an optical DLM ID signal to BMM DSP controller63, via a BMM port62and PD61, which signal identifies the DLM and its particular optical channel group or OCG to controller63. InFIG. 6, DLM17at START102first insures that the power to lasers14in TxPIC10is off as indicated at step104. Next, at step106, DLM17is patched to a desired BMM port62of a respective BMM60, which particular port is identifiable by BMM DSP controller63through a DLM ID signal received through a particular input photodetector (PD)61A,61B,61C, or61D. As seen at step108, the DLM attenuator22is then set HIGH so that minimal power is permitted at the DLM output followed by turning on of TxPIC laser power. Next, as shown at step110, a communication signal is sent from the patched, and now aggressor, DLM17, via a modulated signal from LF MOD24and superimposed of the attenuated OCG signal to BMM DSP controller63, through input photodetector61, identifying the particular DLM17and its associated OCG within the signal band, such as a sub-band in the C band or L band.

In the meantime, at BMM60beginning at START112, BMM controller63is looking for a DLM ID signal on an associated photodetector61as it scans across the photodetector outputs. Controller63in this case may cycle through each of the respective photodetector outputs that have not yet been authenticated to determine if an aggressor DLM is now possibly patched to an aggressor DLM. As seen at step116, if a communication signal has not been received from the aggressor DLM17, BMM controller63continues to look, per step114, until such a signal is received, at which time a determination is made, per step118, as to whether the DLM ID received from the aggressor DLM17is the expected OCG and DLM at the particular BMM port62. If it is not the expected DLM and associated OCG, as determined at step120, then an alarm is sent to the operator, as depicted at step121, indicative of an incorrect patching of the aggressor DLM17. On the other hand, as seen at step120, if BMM authenticates that the DLM and its associated OCG signal are those expected at the particular BMM port, then, BMM DSP controller63at step122dispatches an acceptance signal to the aggressor DLM17. This signal may be, for example, an electrical signal sent to the aggressor DLM17via network element controller101. At the DLM side, if the acceptance signal is received at step124, then, the LF MOD24is stopped, as seen at step132, followed by the setting of the attenuator22or59to LOW at step133so that the operation of PIC lasers14in TxPIC10can be set to full power condition, followed by the commencement of the power control loop between the DLM and the BMM as described in copending and incorporated patent application, Ser. No. (P076).

During step110, DLM LF MOD24continually sends its request for identification to BMM60during a predetermined time period. This is represented by step124where no acceptance signal has been yet received and at step126, the predetermined minimum time period has not yet elapsed (condition “no”) so that the DLM ID signal is repeated at step110. Thus, the DLM17continues sending its identification request at step110until an acceptance is received from BMM60at step124. If, on the other hand, an acceptance signal is not received from BMM60within the predetermined minimum time period at126, such as, for example, but not limited to, a ten minute period of time (condition “yes”), then the DLM LF MOD24is stopped, as indicated at step128, and a operator manual reset is required before resignaling from the aggressor DLM17to BMM60is carried out again via steps108and110. This also permits the operator to check for any errors in patching an incorrect DLM to a particular BMM port or patching a correct DLM to an incorrect BMM port.

A still further way of accomplishing optical autodiscovery is an embodiment of detuning the wavelength grid of a TxPIC module so that its output OCG signal wavelength grid is frequency shifted in a manner as illustrated inFIG. 8where three signal wavelengths are illustrated out of N such signal channels on a TxPIC10. By temporarily shifting the wavelength grid of the OCG signal154so that the wavelength grid is detuned from the standardized wavelength grid, such as the ITU grid, to a shifted OCG wavelength grid156by a shifted spectral amount indicated at155. With this shifted signal grid at156, the OCG signal can now be provisioned without any attenuation since none of its output wavelengths, forming part of the aggressor DLM shifted OCG would interfere with any other signal wavelengths on other previously provisioned victim DLMs since the detuned or shifted signal wavelength grid at156is no longer wavelengths on any standardized wavelength grid, such as the ITU grid. As a result, the TxPIC VOAs22may not be further necessary in the execution of the autodiscovery procedure as set forth inFIG. 6. However, they would be necessary, for example, in carrying out active control loop for power control of OCGs being patched to the same BMM, for example, as set forth in incorporated patent application, Ser. No. (P076), infra. Such a detuning can be either a red shift or blue shift of the PIC wavelength grid. Once authentication is complete, the OCG shifted wavelength grid156is shifted back to its proper standardized wavelength grid position at154. This embodiment would require that no wavelength locking be active on the TxPIC module during the time of wavelength grid shifting in order to safely accomplish the autodiscovery process.

Furthermore, due to the fact that the OCG wavelength grid154is detuned as illustrated inFIG. 8, also a reduced BER penalty will be experienced as illustrated in connection withFIGS. 7 and 9. The solid line curve150inFIG. 7illustrates the BER penalty experienced over a range of relative power differences between a victim DLM at full power OCG signal output and an aggressor DLM at attenuated power OCG signal output over a given range of power. As illustrated inFIG. 9, this relative power difference is what is experienced before there is any imposed temporary wavelength grid shift of OCG signal154so that the interference penalty shown at curve108inFIG. 9is at its highest point where the BMM provisioned victim DLM would experience peak interference due to a presence of optically conflicting aggressor DLM OCG channels. It can be readily seen that by shifting the wavelength grid154of an aggressor DLM to be patched to a BMM port, the interference penalty is reduced by an amount151shown inFIG. 9, which also reduces the BER penalty as depicted by dash lined curve152inFIG. 7by the same amount151from a higher BER penalty at position Y1, to a lower BER penalty at position Y2. This is an additional advantage in deploying this wavelength grid shift of the DLM OCG output signal156which can be accomplished in the aggressor DLM by shifting all of the tuned wavelengths of TxPIC lasers14. For example, this shifted wavelength grid can be initiated by applying additional heat uniformly across heaters13of the entire PIC laser array of TxPIC10. InFIG. 6, the step of the offset of the aggressor OCG wavelength grid to position156is depicted at step107and the reset of that offset back to the standardized wavelength grid to position154is depicted at step133. Again, the set attenuator High at step108and set attenuator Low at step133may be eliminated, if desired.

While the invention has been described in conjunction with several specific embodiments, it is evident to those skilled in the art that many further alternatives, modifications, and variations will be apparent in light of the foregoing description. For example, the exemplified communication discussed in this disclosure is explained in connection with a digital line module or DLM seeking recognition and acceptance via a low frequency modulation signal, by a band multiplexer module or BMM. However, it will be evident to those skilled in the art that the exemplified optical autodiscovery procedure inFIG. 6can be adopted between any two optical or electro-optical modules in any kind of system where a first (aggressor) optical or electro-optical module seeks recognition and acceptance by a second optical or electro-optical module upon their mutual optical connection or coupling and there is a concern that the first optical or electro-optical module may materially affect the successful connection of previously connected or provisioned (victim) optical or electro-optical module to the same second optical or electro-optical module. Further, the communication between the first and second modules may be all electrical modulated messaging, partly electrical and partly optical modulated messaging as is the case in the foregoing embodiments, or all optical modulated messaging. All optical messaging is not necessary in the foregoing embodiments since there is no provisioning of optical signals from a BMM to a DLM because the provisioning of received and disbanded OCG signals for output to respective DLMs has already been provisioned for the same OCG signals to be properly patched to the BMM.

Thus, the invention described herein is intended to embrace all such alternatives, modifications, applications, and variations as may fall within the spirit and scope of the appended claims.