bluuebunny/crossref_metadata_2025 huggingface dataset:
Operating Curves for Optical Bistable Devices
Authors: Wheatley P. , Midwinter J.E.
Published: February 2023

There is much interest in the use of optical bistable devices as logic gates for optical processors. Although desirable properties have been reported, it is difficult to see how these are offset by less desirable ones. All properties of the device can be controlled to a certain extent, principally by the bias conditions. Here we show how steady state and dynamic responses vary simultaneously with these parameters. These operating curves can be used to see the capabilities of a device or to choose the optimum bias conditions.
A 1.5 Gigabit-per-Second, Time-Multiplexed Photonic Switching Experiment
Authors: Erickson J. R. , Nordin R. A. , Payne W. A. , Ratajack M. T.
Published: February 2023

Current experimental Ti:LiNbO3 switching systems need electronics for control, regeneration, and compensation for the imperfections of the photonic switching fabric. These early photonic switches do, however, have advantages over their electronic counterparts: 1) Their switching fabric can carry 100 Mb/s or 10 Gb/s with little modification, 2) Their switching fabric is synergistic with fiber transmission, especially when optical amplifiers can be used, 3) They provide valuable experience in optics and photonic switching, 4) They give insight into the future of optical switching and how the signaling and protocols of the network need to evolve to accommodate this emerging technology[1].
GaAs-AlAs Monolithic Microresonator Arrays
Authors: Jewell J. L. , Scherer A. , McCall S. L. , Gossard A. C. , English J. H.
Published: February 2023

Miniaturization of optical logic devices has long been considered to be a key to minimizing their energy requirements but difficult to achieve1-4. We demonstrate a straightforward technique for fabricating arrays of GaAs/AlAs Fabry-Perot etalon devices (microresonators) as small as 1.5 μm in diameter. The growth of integrated GaAs-AlAs nonlinear etalons by molecular beam epitaxy5 (MBE) represents a tremendous advance over previous fabrication techniques6. From the sample of reference 5 we have formed close-packed arrays of monolithic "posts" or microresonators 1.5-5 μm across by ion-beam assisted etching7 and have performed optical NOR/OR gating experiments on them using picosecond pump and probe pulses. These microresonators represent a qualitative advance over the GaAs devices reported by Lee et al8. In that work pixels 9×9 μm square were formed in the active material only, and then sandwiched between dielectric mirrors in the usual way.6 Growth of integrated devices by epitaxial techniques such as MBE allows us to etch right through both mirrors and the active material. This is critical since in an optimized nonlinear etalon the dielectric mirrors comprise most of the total thickness. The lateral optical confinement in these waveguiding structures allows efficient operation with diameters as small as one can focus the light. Elimination of carrier diffusion9,10 out of the devices permits very close spacings. Reduction of energy requirements is expected due to the decreased volume of interaction. Finally, surface recombination8,11 on the sidewalls of the microresonators should produce fast relaxation times. Our experiments show reduced energy requirements (factor of >8), essentially uniform response over small arrays, practically no crosstalk with 3-μm center-center spacing, ~200 ps full recovery time, and thermal stability at 82 MHz operating frequency.
A Rigorous Analysis of Intersecting Waveguides
Authors: McCaughan L. , Agrawal Niraj
Published: February 2023

Intersecting waveguides are becoming an important guided wave element for integrated optics. The simplicity of the geometry, i.e., an absence of S-bends, makes it possible to achieve higher levels of switch integration with a switch element based on this geometry than is possible with directional couplers. Cross-connections between elements of integrated optical circuits are also possible because inter-waveguide coupling is a strong function of the crossing angle. No unified theory has thus far been constructed to explain all of the observed optical characteristics of various intersecting geometries. We report the derivation of a closed form expression which does quantitatively agree with experimental observations. As the results of our calculations show, intersecting waveguides have unique optical properties which cannot be predicted by seeking analogies with directional couplers.
A Photonic Switching Demonstration Display
Authors: Erickson J. R. , Hseih C.G. , Huisman R.F. , Larson M.L. , Tokar J.V. , Bogert G.A. , Murphy E.J. , Ku R.T.
Published: February 2023

As fiber optic communication proliferates, it becomes important to explore the possibilities of photonic switching. As a near-term photonic switching technology, titanium-diffused lithium niobate (Ti:LiNbO3) needs to be evaluated by its use in experimental systems. In this display, a Ti:LiNbO3 array switches video from cameras to monitors.
Photonic Switching with Stripe Domains
Authors: Torek E.J. , Krawczak J.A. , Nelson G.L. , Fritz B.S. , Harvey W.A. , Hewitt F.G.
Published: February 2023

This paper describes a cross-bar switchboard for optical fibers. The switchboard is all optical, solid state (i.e. no moving parts), rugged, wide temperature, fast (2µsec), non-blocking, latching (i.e non-volatile), requires no initial polarization, is capable of switching both digital and analogue signals, and is theoretically capable of handling very large numbers of inputs and outputs in a single stage. The light is deflected from input fiber to any output fiber by a stripe domain deflection element, so there are no splitting losses; the efficiency does not decrease as more outputs fibers are added.
Single-Mode Fiber Switch with Simultaneous Loop-Back Feature
Authors: Young W. C. , Curtis L.
Published: February 2023

As applications for lightwave systems expand, new challenges for photonic switches are constantly evolving and some of these challenges can be satisfied by moving-fiber type switches. In the case of optical fiber networks having many regenerative nodes, it is necessary to bypass those nodes that are not in use and to ensure that in-operative nodes are not permitted to enter the network and cause a total network failure.1 In this paper, we report on a moving-fiber-array switch that provides these important switching functions in evolving single-mode fiber (SMF) networks. In particular, the switch is designed to provide the bypass function through only one SMF butt-joint; therefore, it exhibits very low insertion loss and permits networks to be designed that have a large number of off-line nodes for a large percentage of the time. A second feature of this switch is that while in the bypass position the switch establishes an optical loop-back circuit, for the regenerative node (a receiver/transmitter combination), permitting self-testing of the node. If the self-test is negative, due to an in-operative node, then the switching function (switching to the on-line position) can be blocked thereby avoiding a total network failure. In the event a node failure occurs after switching, the actuator is de-energized and the switch returns to the normal position (bypass position). In the on-line position the optical path through the switch uses low loss single-mode fiber to multimode fiber (SMF/MMF) "photon-bucket" type joints between the line input and the node’s receiver, and again only one SMF/SMF joint between the node’s transmitting SMF and the network’s SMF. Solenoid actuation is used for achieving the on-line position and a compression spring is used to return and hold the switch in the bypass position.
An All-Optical Switch for Signal Routing Between Fibres
Authors: Paton C.R. , Smith S.D. , Walker A.C.
Published: February 2023

Non-linear interference filters (NLIF) incorporating ZnSe spacers were first shown to exhibit optical bistability in 1984 [1,2]. Since then they have been successfully used in a number of digital optical circuit demonstrations [3]. Although these devices, which rely on a thermally induced nonlinearity, have limited low-power switch speeds (0.1 µs-100 µs) they have a very high transmission bandwidth, up to several THz, and can therefore act as an all-optical relay. They are therefore excellent candidates for spatial switching, or signal routing applications. A single NLIF may be configured as a 2 × 2 spatial switch by using both reflection and transmission outputs, as shown in fig. 1. An array of such devices may be used to form a non-blocking switch network or crossbar switch [4].
Photonic Switching Components: Current Status and Future Possibilities
Authors: Midwinter J E
Published: February 2023

The interest in optical switching seems to stem from several factors. One might well be cost, avoiding the need for two opto-electronic interfaces at the switching node. Further to that, in a local or campus network, the low insertion loss and bandwidth of single mode fibre offers the possibility of truly "transparent" networks, in which the format and data rate are set by the communicating terminals and the routing is achieved independently in a way that does not require synchronous or rigidly formatted data streams. Such switches may also support bidirectional operation both within the fibre and the switch. Another attribute of such technology is likely to be the provision of very large communication bandwidths as well as the usual optical advantages of low cross talk and distortion.
Overview of Switching System/Network Architectural Possibilities
Authors: Yasui Tadahiko , Kikuchi Katsuaki
Published: February 2023

To ensure the provision of high-speed, broadband services, new telecommunications networks should be constructed using both high-speed, broadband switching systems as well as high-speed transmission systems.
Thermally Stable, Optically Bistable AlGaAs Etalon with a Silver Combined Mirror and Heat Sink
Authors: Masseboeuf E. , Sahlen O. , Olin U. , Nordell N. , Rask M. , Landgren G.
Published: February 2023

Room-temperature, low-power and nanosecond switching of bistable AlGaAs étalons with a silver mirror/heat sink, which are thermally stable for half a second, is reported.
Time Response of a Crossed Resonator
Authors: Capron Barbara A. , Derstine Matthew W. , Holm David A.
Published: February 2023

We present a time dependent model of an optical switching device consisting of two crossed Fabry-Perot resonators filled with a nonlinear medium. Results are shown for parameters appropriate for nonlinear organic media in integrated optic geometries. In the small signal limit, gain-bandwidths of hundreds of GHz are predicted. With pulsed inputs, gains of 10 and larger can be achieved without pulse breakup.
Two-Dimensional Perfect Shuffle Networks
Authors: Taylor M. G. , Midwinter J. E.
Published: February 2023

A new approach to the design of two dimensional multistage interconnection networks is presented. The method provides a general solution to the problem of finding algorithms for such networks, by converting those already known for 1D networks.
All-Optical Shift Register Using Symmetric Self-Electro-Optic Effect Devices
Authors: McCormick F. B. , Lentine A. L. , Chirovsky L. M. F. , D’Asaro L. A.
Published: February 2023

We demonstrate an all optical shift register using a single reflective Symmetric-Self Electro-optic Effect (S-SEED) device array. The space­multiplexing interconnection techniques used are extensible to large arrays of devices. The cascaded devices are all resident on the same array and are driven at relatively low power levels by laser diodes.
Optical Interconnection Networks Employing Multiplexed Cross Points
Authors: Healey P.
Published: February 2023

New multi-stage image switching networks employing spatially multiplexed crosspoints and birefringent interconnects are described which simultaneously reduce both the crosspoint count and the switch control complexity to the theoretical minimum. The networks may be one-sided or two-sided, and both types are non-blocking in the strict-sense.
Broadband Electronic Switching
Authors: Berthold J. E.
Published: February 2023

As we seek application for photonic technology in future broadband switching systems we must be aware of the changing nature of switching. While circuit switching will continue to find application in telecommunications facilities protection, network rearrangement, and in providing very high speed channels to subscribers, a packet­like transport called Asynchronous Transfer Mode or ATM is expected to play an increasingly important role. This memo describes some functions that may be provided in an ATM switch, and reviews progress in high speed electronics technology for circuit and ATM switching as a technology baseline for our use in assessing opportunities for photonic technology.
Switch Matrix with Semiconductor Laser Amplifier Gate Switches: A Performance Analysis
Authors: Gustavsson Mats , Thylén Lars
Published: February 2023

A performance analysis of a space division switch matrix based on semiconductor laser amplifier gate switches is presented in terms of technological and systems requirements.
High-Gain Optical Transistors Resistant to Pump Instability
Authors: Maier Alexander A.
Published: February 2023

Self-switching of radiation in nonlinear systems with two unidirectional distributionally coupled waves is considered for general case when both waves are fed into the system and their nonidentity is taken into account. The possibility is discussed of optical transistors with a high gain that are resistant to pump intensity instability.
Novel Light Modulator and Optical Transistor for the Far-Infrared Region: A Proposal for a Modulable Mirror
Authors: Kuijk Maarten , Vounckx Roger
Published: February 2023

A novel concept for modulating far infrared light is presented. For TM-polarized light incident on a layer of a dens free electron gas high reflection properties arise due to plasma resonance. A change in electron density or in electron effective mass modulates the electron plasma frequency and hence the reflectivity of the layer. This leads to a small, integrable, and fast modulable mirror which may be used as a switching device (ellectrically, or optically driven).
Photonic Packet Switch Using Optical Buffer Memories
Authors: Suzuki S. , Suzuki H. , Kasahara K. , Fujiwara M. , Takeuchi T.
Published: February 2023

Extremely high-speed photonic packet switches using wavelength-division multiplexed fiber loop buffer memories or massively parallel interconnected optical memory two-dimensional array are proposed.
Diffusion-Assisted Optical Switch: A New Optical Logic Device
Authors: Sizer Theodore , Livescu Gabriela , Cunningham Jack , Miller David A. B.
Published: February 2023

Theoretical and experimental results from a new optical logic device are presented which indicate that it has speeds of many GHz, sub 100 femtojoule energies, and is easily fabricatable.
Multiple Quantum-Well Asymmetric Fabry-Perot Etalons for High-Contrast, Low-Insertion-Loss Optical Modulation
Authors: Whitehead M. , Parry G. , Rivers A. , Roberts J. S.
Published: February 2023

A method of improving the performance of an electroabsorptive optical modulator is presented. By using GaAs-AlGaAs multiple quantum wells as the active region of an asymmetric (low-finesse) Fabry-Pérot cavity it is possible to achieve both large, broad-band reflection changes and high contrast with low operating voltage.
Batch-Fabricated Symmetric Self-Electro-Optic Effect Devices
Authors: Chirovsky L. M. F. , D’Asaro L. A. , Tu C. W. , Lentine A. L. , Boyd G. D. , Miller D. A. B.
Published: February 2023

The Symmetric Self Electro-optic Effect Device has been previously shown to have the minimum of the device characteristics necessary for digital optics systems and many additional desirable features. We describe here the design and fabrication of arrays of Symmetric Self Electro-optic Effect Devices with an internal dielectric minor. Advantages of this design compared to previous transmissive designs include: amenability to batch fabrication, shorter switching times, increased output beam contrast and better heat-sinking. We present details of the necessary epitaxial growth, the dielectric mirror design, the device structure, the array layouts, the fabrication techniques and the testing performed. The results of the testing show that large arrays of reflective Symmetric Self Electro-optic Effect Devices can be batch fabricated and that these arrays are suitable for system tests.
Compact InGaAsP Quantum-Well Electro-Optic Waveguide Switch
Authors: Zucker J. E. , Jones K. L. , Young M. G. , Miller B. I. , Koren U.
Published: February 2023

We have utilized the large excitonic electrorefraction and tunable bandgap in high-quality InGaAsP quantum wells to produce compact directional coupler switches operating at 1.55 µm wavelength.
Vertical Cavity Single-Quantum-Well Laser
Authors: Jewell J. L. , Huang K. F. , Tai K. , Lee Y. H. , Fischer R. J. , McCall S. L. , Cho A. Y.
Published: February 2023

We have achieved room-temperature pulsed and cw lasing at 980 nm in an optically-pumped vertical cavity structure grown by molecular beam epitaxy containing only a single quantum well (SQW) of In0.2Ga0.8As. Limited gain due to the extremely short active material length of 80 Å implies that losses due to absorption, scattering and mirror transmission are extremely low. Using 10 ps pump pulses at 860 or 880 nm the estimated energy density absorbed in the spacer was ~12 fJ/µm2 at threshold, indicating a carrier density ~4 times that required for transparency. Continuous wave pumping yielded an estimated threshold absorbed intensity of ~7 µW/µm2, and a ~33 % slope efficiency.
Optical Processing in Photonic Switching Systems
Authors: Kobayashi Ikutaro
Published: February 2023

The advanced features of optical technologies will trigger further evolution of communication switching systems. Optical switches will be applied to a small-scale wideband multimedia PBX in a few years. Then, primitive optical processing will be required for optical FD switching systems when light FDM transmission is installed in a subscriber loop. In the next century, optical processing will get popular and optical switching and processing will be integrated in an advanced communication network. In the course, the optical switching fields will offer simple examples applicable to practical systems and will stimulate the evolution of optical processing.
Architecture on Optical Processing for Communications
Authors: Masuda S. , Rokugawa H. , Yamaguchi K. , Fujimoto N. , Yamakoshi S.
Published: February 2023

We were able to achieve direct optical accessing from an optical highway using bistable laser diodes. A simple architecture was used without the need for optic to electric or electric to optic conversion for the optical switching.
Nonblocking Photonic Space Switch Architectures Utilizing Acousto-Optic Deflectors
Authors: Huang P. C. , Stephens W. E. , Cheng S. S. , Banwell T. C. , Reith L. A.
Published: February 2023

A 4×4 multicasting photonic space switch architecture with minimal hardware and control complexity has been demonstrated utilizing commercially available acousto-optic Bragg cells at λ = 0.83 µm. Insertion loss of 15 dB, crosstalk of -24 dB, extinction ratio of 33 dB, and polarization difference of 0.8 dB are reported.
High-Definition TV Photonic Space-Division Switching System Using 8×8 Polarization-Independent LiNbO3 Matrix Switches
Authors: Suzuki S. , Nishimoto H. , Iwasaki M. , Kajitani S. , Kondo M. , Shikada M. , Ashibe M. , Akashi F.
Published: February 2023

A photonic space-division switching system using 8X8 polarization independent LiNbO3 matrix switches has sucessfully operated in switching HDTV signals, transmitted through ordinary optical fibers.
Improved Operation of a Two-Core Fiber All-Optical Switch Using Femtosecond Square Optical Pulses
Authors: Silberberg Y. , Weiner A. M. , Fouckhardt H. , Leaird D. E. , Saifi M. A. , Andrejco M. J. , Smith P. W.
Published: February 2023

We measure all-optical switching in a dual-core fiber nonlinear coupler. By using femtosecond square pulses, we obtain enhanced power transfer and sharp switching transitions.
All-Optical Kerr Amplification and Wavelength Switching on a Single Biréfringent Fiber
Authors: Davison A. S. , White I. H.
Published: February 2023

An all-optical Kerr amplifier using a single fibre is reported. The polarisation of a high power optical pump is modulated by a weak optical signal, via the high speed Kerr effect. The information is switched from the signal wavelength to the pump wavelength. A novel form of cascading of Kerr amplifiers is described whereby gains of 100 are projected, limited by the onset of other optical non-linearities.
Extendible Optical Interconnection Network
Authors: Smith D. W. , Healey P. , Cassidy S. A.
Published: February 2023

This paper describes a new form of non-blocking extendible multi-stage optical interconnection network that combines one, two, or more degrees of switching freedom via access to a common multiple access bus. The common bus is capable of exploiting the spatial, spectral, and temporal multiplexing powers of optics, significantly reducing the number of physical interconnections required.
A Low-power High Gain Optoelectronic Switch based on Quantum Stark Effect and its use in logic operations
Authors: Goswami S. , Li W. , Bhattacharya P. , Singh J.
Published: February 2023

Quantum Confined Stark Effect(QCSE)1-4 holds a great deal of promise for active switching devices controllable by light and/or electronics. This effect allows one to tailor the device response to such a great extent that at least in principle a number of powerful devices can be conceived and demonstrated.
Broadband Computer Network Based on Optical Subcarrier Multiplexing
Authors: Bates Richard J. S. , Varma Anujan
Published: February 2023

An optical passive-star network consists of a number of stations interconnected in a star topology by means of a central passive optical coupler. These networks offer a reliable and inexpensive means for implementation of local-area and room-area networks, multiprocessor interconnection networks, I/O buses, and workstation clusters. Optical subcarrier multiplexing (SCM) provides a means to divide the aggregate bandwidth of the optical medium in an optical passive-star network into multiple channels, each offering a fraction of the aggregate bandwidth. A network testbed to evaluate the SCM technology and its likely applications to computer-system interconnection are the subject of this paper.
Photonic Packet Switch Based On VSTEP Two-Dimensional Array
Authors: Suzuki S. , Kasahara K.
Published: February 2023

High-speed packet switches, which can handle wide-bitrate-range data streams in an integrated manner, are expected to play an important role in future broadband networks. Introduction of photonic technology to very high-speed packet switches has been proposed[1]-[6]. Among these high-speed packet switches using photonic technology, the packet switch, using VSTEP’s (Vertical to surface transmission electro-photonic devices) [7] [8] as optical buffer memories, is expected to achieve high switch performance in small size[5]. The VSTEP two-dimensional (2D) array can be used not only as memories but also header-driven routing fabrics[9]. This paper discusses a photonic packet switch using VSTEP 2D array as buffer memories and a header-driven routing fabric with priority control.
Photonic Fast Packet Switch with Gain
Authors: Fortenberry R. M. , Ha W. L. , Tucker R. S.
Published: February 2023

Packet switching has become an attractive means of transferring digital information across high speed communications networks. The self-routing of packets using a photonic switch that is transparent to the optical information bandwidth [1] has several advantages over electronic switching, including flexibility of data format and the ability to avoid electronic speed bottlenecks. It has been shown [2] that in photonic packet switching data transfer rates for the information content of a packet (the payload) can be made independent of the address header data rate. Thus even for very high capacity systems, electronics can be used to detect and decode the address header and to control the routing switch. Since the address header of a packet is small compared to the payload, this approach does not significantly decrease the information transfer efficiency. Using a hybrid of optical switching and electronic control results in a flexible system which combines the advantages of both technologies.
Control injection schemes for photonic switching architectures
Authors: Cloonan T. J. , McCormick F. B. , Lentine A. L.
Published: February 2023

All photonic switching architectures require control information to be injected into the nodes of the network fabric to permit appropriate routing of the traffic. A typical photonic switch (Fig. 1-4) consists of nodes arranged in stages (node-stages) which are separated by optical links (link-stages). Every node in every node-stage must have control signals routed into it in addition to the data inputs and data outputs, and depending on the reconfiguration rate of the network, the aggregate bit-rate of the control inputs entering a node-stage can sometimes be as high as the aggregate bit-rate of the data passing through a node-stage. Thus, it should be apparent that the problem of control injection is not at all a trivial problem. Control injection is an important aspect of photonic switches that should probably by given more attention, because the manner in which control is injected into the network has a large effect on the performance and operating capabilities of the network. This paper will study these effects for four different control injection schemes: 1) distributed control scheme with self-routing packet headers, 2) centralized control scheme with self-routing packet headers, 3) centralized control scheme with spatial light modulators (SLMs), and 4) centralized control with direct node injection.
Linked InGaAs/InP MQW Modulator Arrays for Neural Network and Photonic Switching Applications
Authors: Rejman-Greene M A Z , Scott E G , Webb R P , Healey P
Published: February 2023

Square arrays of InGaAs/InP MQW modulators are attractive devices for high speed switching of optical signals, especially where operation in transmission simplifies the system design. For example, simple 4×4 arrays have been used in demonstrations of i) parallel optical interconnect with the modulators driven by standard high speed CMOS to provide a capacity of 100 MBit/s x 16-channels1 and ii) an opto-electronic implementation of neural network operating at 50MBit/s2. The electrical addressing of individual devices in such arrays becomes more dificult as the number of elements increases, with packaging of such large arrays for use in transmissive mode posing further problems. For some applications, as in the neural network demonstrator shown in Fig 1, individual modulators need not be addressed, and more extensive systems can be built and packaged by linking individual modulators during the fabrication scheme, to provide line-addressed arrays. Furthermore, by applying the technique of double-sided epitaxy3, to the modulator-detector pair, and linking rows of devices in orthogonal directions on the two faces of the substrate material, a considerable miniaturisation of the experimental design may be achieved.
Asymmetric Fabry-Perot Multiple Quantum Well PIN Diodes and S-SEEDs for Intra-Chip Optical Interconnections
Authors: Farhadiroushan M. , Selviah D. R. , Midwinter J. E.
Published: February 2023

With advances in VLSI and WSI technology, the realization of high speed electronic systems becomes increasingly limited by the performance of metallised tracks. It has been suggested that optics can provide potentially a low-energy and broad-band communication interface within electronic processors(1-4).
Error-Free Operation of Wavelength Conversion Laser for Multistage Photonic Cross-Connect Node
Authors: Rokugawa H. , Fujimoto N. , Nakagami T. , Wakao K.
Published: February 2023

B-ISDN requires a throughput in excess of 50 Gbit/s, even in a subscriber loop for full-motion video transmission. To provide the network capacity and to provide flexibility, optical signal processing technology is used, especially that of optical wavelength-division multiplexing. We have already proposed such configuration of photonic cross-connect nodes that perform nonblocking cross-connection with two stages by utilizing multi wavelength selective filters(MWSFs)[1]. In our proposed configuration, a large capacity can be provided with multistage connection, and signal wavelength conversion will be essential at the connecting stage between two groups of the basic switches when connected by multiple stages. In the connecting stage, use of wavelength conversion devices (WCDs) such as wavelength conversion lasers(WCLDs) has the advantage of hardware scale reduction in large-scale connecting systems, thus eliminating electronic circuits such as O/E or E/O converters.
One gigabit per second wavelength filtering with Distributed Bragg Reflector laser filters in two-channel system experiments
Authors: Sahlén Olof , Öberg Magnus , Nilsson Stefan
Published: February 2023

To fully exploit the advantages of optics for switching applications, the wavelength dimension should be utilised. An optimum photonic switching architecture probably combines optical space and wavelength switching with electronic time switching. Tunable emitters and tunable optical filters are key devices for developing such systems. A category of devices that are particularly interesting is the one comprising tunable laser diodes, that can be operated either as emitters (when biased above the oscillation threshold) or as narrowband filters (biased below the threshold). Filtering has previously been demonstrated in tunable two-section Fabry-Perot lasers [1], in tunable multi-section DFB lasers [2], [3] and in tunable two-section DBR lasers [4].
Frequency Conversion by Four-Wave-Mixing in Semiconductor Laser Amplifiers: How to relax the filter problem?
Authors: Großkopf G. , Ludwig R. , Schnabel R. , Schtmk N. , Weber H.G.
Published: February 2023

In /1/ an all optical frequency conversion method was reported, which is based on nearly de generate four-wave mixing (NDFWM) and homogeneous gain saturation in semiconductor laser amplifiers (SLA). This method promises a frequency conversion range up to about 10 THz (de pending on the gain bandwidth of the SLA), a conversion efficiency η of more than 0 dB, the frequency conversion of a given data signal simultaneously to several frequencies and finally data transparency. However, it restricts the bit rate to ≤ 1 Gbit/s. in two experiments a successful operation of this method was demonstrated /2, 3/. A disadvantage of the frequency conversion method are the severe requirements on the resolution of the optical filter, which is necessary to select the converted data signal out of a multicomponent spectrum generated at the output of the SLA. In this paper we investigate how to relax the requirements on the selectivity of the optical filter.
Gated Optical Latch Based on InGaAs/InP Light Amplifying Optical Switch
Authors: An X. , Beyette F. R. , Feld S. A. , Geib K. , Wilmsen C. W. , Lee H. Y. , Hafich M. J. , Robinson G. Y.
Published: February 2023

Optical switching devices are of much interest in optoelectronic computing systems, especially for optoelectronic integrated circuits. Several types of optical switching devices have previously been developed, such as the self electro—optic effect device (SEED), double heterojunction optoelectronic switch (DOES), an integrated combination of a heterojunction phototransistor (HPT) and a light—emitting diode (LED) called a light amplifying optical switch (LAOS), and pnpn switches. With the exception of the SEED, all of these switches have demonstrated a similar switching I—V curve composed of a high—impedance off-state, a low—impedance on—state and a differential negative resistance region connecting the two as shown in Fig. 1. Most of the switches discussed above can be triggered on with an input light pulse, but they cannot be turned off optically. The only way to turn the switch off without using additional components is to reduce the electrical bias to zero. This switching has been utilized in the implementation of an optical memory which is electrically erasable [1], and an optoelectronic flip-flop based on two parallel pnpn switches using the bias pulse as a clock [2]. From the I—V curve of Fig. 1, it can be seen that there are two possible ways to optically turn the switch off: i) Place an optically sensitive element in shunt with the switch which can reduce the bias across the switch to a level lower than the holding voltage (usually about 0.8 ~ 1.2V); or ii) Place an optical element in series with the switch in order to reduce the current passing through the switch below the critical current. The first approach has been applied successful to the fabrication of an all—optical bistable switch with optical set/reset pulses [3]. This device incorporates an additional HPT in parallel with the switch. We have implemented the second technique by placing an HPT in series with the switch to form a gated optical latch.
Microbeam Interconnections Using Microlens Arrays for Free Space Photonic Systems
Authors: McCormick F. B. , Tooley F. A. P. , Cloonan T. J. , Sasian J. M. , Hinton H. S.
Published: February 2023

Free-space optics offers a means of exploiting the large bandwidths of optical signals and the high densities of optical imaging.[1] Many of the free-space optical computing and switching systems proposed and constructed thus far have relied on conventional imaging using bulk lenses, as in Fig. 1(a).[2] These solutions must provide large space bandwidth products (SBWP) since they offer high resolution over the entire image field. Less than one tenth of the device array area is commonly used for optical I/O, due to fabrication[3] or cross talk issues.[4] The percentage of the total area occupied by the optical I/O windows will decline as the amount of functionality per pixel is increased (e.g. "smart pixels").[1] If the number of optical I/Os remains large, then the object and image fields provided by the lenses must grow. The requirement of high resolution across larger fields will continue to increase the cost and complexity of conventional optical solutions. Additionally, the increased field angles of the beams propagating between the lenses may introduce unwanted polarization effects at the polarization beam splitters and retarders. Since the large SBWP of the bulk lenses is not being fully utilized, it seems reasonable to investigate means by which the required high resolution (<10 μm) could be supplied only at the optical I/O windows. One means of doing this is to provide a separate optical relay system for each I/O, as shown in Fig. 1(b).
Space-variant holographic optical elements for switching networks and general interconnects
Authors: Schwider J. , Stork W. , Streibl N. , Völkel R.
Published: February 2023

Optical interconnects enable the transmission of signals with ultra high frequencies with small crosstalk and rather low waste energy per transmission line. Two fields of application for optical wiring concepts can be discerned, i.e. fixed pattern chip to chip (or board to board) interconnects and reconfigurable switching networks or bus systems where the interconnect path is selected out of a number of fixed interconnects by means of e.g. so-called exchange bypass modules (EBM)1,2.
Photonic Time-Multiplexed Permutation Switching using the Dilated Slipped Banyan Network
Authors: Thompson Richard A.
Published: February 2023

A new switching network architecture, called the Dilated Slipped Banyan Network(DSBN), is proposed for the hub of a photonic active-star Local Area Network (LAN). A lithium niobate implementation of a classical 4-by-4 banyan architecture was proposed[1]: for bit-interleaved time-multiplexing. The DSBN has properties, described herein, that make it more general in size and more amenable to lithium niobate implementation than the classical banyan. Furthermore, since the active-star LAN application could use a word-interleaved data format instead of a bit-interleaved format, the hub switch need not be bit-synchronous with the data.
Growth and Investigation on Photorefractive Properties of SBN Crystals
Authors: Bogodaev N.V. , Ivleva L.I.
Published: February 2023

It is established that one of the most sensitive material among ferroelectrics is strontium barium niobate crystals /SBN/ /1/. Holographic information recording makes great demands of optical quality and size of the crystals. The problem of producing optically homogeneous crystals is greatly complicated due to their doping and polarization processes. We have managed to solve these problems and produce crystals suitable for holographic investigations. SBN crystals, both pure and doped, were grown in the air by the Czochralski method and Stepanov’s technique from platinum crucibles and dies. We have grown nominally pure SBN crystals of composition SrxBa1-xNb2O6, where x=0.61, x=0.75, and doped with Ce, Ti, Mo, Fe. The crystallization rate for Czochralski-grown SBN bules was 5-6 mm/h, for Stepanov-grown SBN plates and rods was 20-30 mm/h. Typical sizes of crystal bulk were 30mm in diameter and 50mm on length, plate sizes were 2.5x35x100mm, rod sizes were 15x15x80mm and 8x8x105mm.
Tungsten Bronze Crystals for Photorefractive Applications
Authors: Neurgaonkar R. R. , Cory W. K. , Oliver J. R.
Published: February 2023

The term "photorefractive effect" has been adopted to refer to optically induced changes of the refractive index which occur in many spontaneously polarized electro-optic materials. Currently, this effect has been studied in a variety of materials, such as BaTiO3, KNbO3, LiNbO3, BSO, BGO (1), and tungsten bronzes such as Sr1-xBaxNb2O6 (SBN), Ba2-xSrxK1-yNayNb5O15 (BSKNN) and Ba2NaNb5O15 (2-5).
Photorefractive Properties of Iron and Manganese Doped Bi4Ge3O12 Single Crystals
Authors: Kovács L. , Moya E. , Pólgar K. , Zaldo C.
Published: February 2023

We report first results on the optical absorption, photoconductivity and visible photorefractive properties of Bi4Ge3O12 crystals doped with Fe and Mn. Optical absorption and photoconductivity response covers the visible and ultraviolet up to about 4.0 eV. The writting and erasure regimenes have been found complex. The origin of the gratings is discussed and calculations of several material parameters are reported.
Considerations on the Optimization and Relevant Characterization of Photorefractive Materials
Authors: Zielinger J.P. , Tapiero M.
Published: February 2023

Photorefractives are very versatile, attractive optoelectronic materials, having a wide range of possible applications. A variety of functions have been demonstrated on a laboratory basis, but so far, only very few of them have found widespread applications. One main reason for this failure seems to be that the preparation of components, with optimal and reliable relevant characteristics, comes up against a fundamental, more and more crucial problem: the lack of a systematic physical and physico-chemical characterization in parallel with optical studies and material processing.
Origin of Sublinear Photrefractive Effects in Barium Titanate
Authors: Brost G.A. , Motes R.A.
Published: February 2023

The band-transport model of Kukhtarev [1] is commonly used to describe the photorefractive grating formation. According to this model the grating formation time should be inversely proportional to the laser intensity. However, experiments performed on barium titanate have shown a response time which has varied with intensity as I−x, where the exponential factor x has ranged from 0.5 to 1.0.[2] In this paper we show by computer modeling of the grating formation that the sublinear dependence of the response time is accounted for by the presence of secondary photorefractive centers.
Characterization of Band-Edge Photorefractive Effect in Compound Semiconductors
Authors: Partovi Afshin , Kost Alan , Garmire Elsa M. , Valley George C. , Klein Marvin B.
Published: February 2023

We have recently shown that at optical wavelengths near the band-edge, non-electrooptic gratings can be used for two beam coupling energy transfer [1]. By combining these gratings with conventional electrooptic gratings, very large gain coefficients can be achieved. We will present measurements of the wavelength dependence of the two-beam-coupling gain in compound semiconductors. A large increase in the amount of energy transfer is observed near the band edge, as compared with values at longer wavelengths. We will discuss the relative magnitude and origins of the mechanisms involved and compare the beam coupling results with direct measurements of the nonlinearities. We will discuss possible applications.
Application of High 2WM Gain in Photorefractive InP:Fe to IR Double Phase Conjugated Mirror
Authors: Gravey P. , Wolffer N. , Picoli G. , Ozkul C.
Published: February 2023

The interest of Double Phase Conjugated Mirror1 (DPCM) for various optical interconnects schemes has been emphasized by several authors2,3,4 but experimental demonstrations were restricted to visible wavelengths. We present here high 2WM gain performances obtained at 1.06 and 1.32 µm with InP:Fe crystals grown at CNET LANNION and report on the observation of DPCM at 1.06 µm in the same material.
Enhanced Photorefractive Gain in the Bulk Semiconductors GaAs:EL2 and CdTe:V on a 5 psec Timescale
Authors: Smirl A. L. , Boggess T. F. , Schroeder W. A. , Stark T. S. , Norwood D. P. , Valley G. C.
Published: February 2023

Recently, we reported extensive measurements of the energy transfer, via the photo-refractive effect and transient energy transfer, in picosecond two-beam coupling experiments in semiinsulating GaAs:EL2.1 In that case, 30 psec pulses from an active-passive mode-locked and Q-switched Nd:YAG laser system were used to generate a grating with a period of 1.7 µm in the semiconductor. That experiment was conducted in a regime where the laser pulse duration is an order of magnitude larger than the time required for the electrons to diffuse one grating period in the conduction band. Under these conditions, the two-beam coupling geometry was successfully modelled using a numerical solution (with no free parameters) to the equations describing the freecarrier dynamics and nonlinear material response of GaAs:EL2 during the optical interaction. Similar agreement between the theory and experimental data was obtained for the doped semiconductors CdTe:V and InP:Fe.
A Comprehensive Description Of Space-Charge Field Behaviour Using A.C. Enhancement Techniques
Authors: Hall T.J. , Powell A.K. , Stace C. , Swinburne G.A. , Walsh K.
Published: February 2023

The realisation of optical computing depends ultimately on the development of materials which allows the interaction of two light beams at low intensity and on a short time scale. To date, only photorefractive materials can satisfy these requirements. However, photorefractive materials with the fastest response time, e.g. BSO (ms) and GaAs (µs), do not have large electro-optic coefficients and thus require an enhancement technique to be of any use.
Phase Conjugate Resonators and Bistable Oscillations in BaTiO3
Authors: Venkateswarlu Putcha , Dokhanian Mostafa , Sekhar P. Chandra , Jagannath H. , George M. C.
Published: February 2023

Kwang and Yariv(1) used a single domain BaTiO3 crystal to form a ring passive phase conjugator (RPPC) and auxiliary resonators pumped by a multi-mode Ar+ laser at 4880Å. The auxiliary resonators were bistable. Jagannath et. Al(2) from this laboratory, reported the operation of a unidirectional ring resonator (UDRR) in addition to the RPPC and found bistability between the two. They also observed a linear passive phase conjugator (LPPC) which is bistable with the RPPC. It was found that auxiliary oxci nations between the crystal and a mirror are bistable separately with the UDRR and the LPPC.
Quasi-Nondestructive Readout of Holographically Stored Information in Photorefractive Bi12SiO20 Crystals
Authors: Delboulbé A. , Fromont C. , Herriau J.P. , Mallick S. , Huignard J.P.
Published: February 2023

We report the existence of a room temperature hologram fixing process in certain Bi12SiO2 (BSO) crystals, which appears to be due to the formation of a complementary grating of positive charges that compensates the photo-induced electronic space-charge field(1,2). Uniform illumination of the crystal with green light, in presence of an external D.C. electric field, erases the deep-level electronic charge pattern and reveals the positive charge grating which then decays with its own characteristic decay time. We believe, in agreement with the work of Strohkendl(3), that the hole charge pattern involves shallow traps. Since these traps can be thermally activated, the decay time constant can be further increased significantly by lowering the crystal temperature.
Investigations on Hologram Fixing Process in Sillenite Type Photorefractive Crystals
Authors: Miteva M. G.
Published: February 2023

The holograms fixing process in very well known sillenite type photorefractive crystals Bi12(Ge, Si, Ti)O20 has important implications for various applications. An effect of prolonged memory of holographic recording with no applied electric field in photorefractive Bi12TiO20 (BTO) crystals at room temperature has been reported.1,2 The effect is established for high frequency holographic grating with K = 2π/Λ ~ 3×105 cm-1, where Λ is the grating period.
Orientational dependence of photorefractive two-beam coupling in InP:Fe
Authors: Strait J. , Reed J. D. , Kukhtarev N. V.
Published: February 2023

Several groups have studied photorefractive two-beam coupling in cubic crystals of symmetry group
4¯3m, including GaAs1-7 and InP.7-11 In these experiments, the grating vector
q→ usually was along the
[11¯0] or [001] crystal axis, the "canonical" orientations. Recently it was shown that in Bi12SiO20, a crystal of symmetry group 23 having an identical form of electro-optic tensor but possessing an additional optical activity,12 rotation of the crystal from the two canonical orientations can increase energy exchange.13 In this paper we show that it is possible to obtain a 15.5% increase in energy transfer by rotating an InP:Fe crystal from the canonical positions, revealing the physical mechanism of this effect in the absence of optical activity.
Optical Image Processing : Spatial Filtering by Photorefractive Materials
Authors: Li H.W. , Gazengel J. , Xuan N.P. , Ferrier J.L. , Bourdin J.P. , Rivoire G.
Published: February 2023

The nonlinearities of photorefractive materials such as Fe:LiNbO3, BSO, BGO,… are used to filter the Fourier spectrum of an object. Image processing techniques, such as contrast inversion or contrast enhancement of amplitude objects, and phase objects visualization are thus obtained with simple optical devices and low power cw lasers.
Size Effects in Volume Holograms Recorded in Photorefractive Crystals
Authors: Dubois Frank , De Schryver Fabien , Lemaire Philippe
Published: February 2023

In several applications as pattern recognition by dynamic coherent optical correlation, interference patterns whose typical width is of the same order of magnitude or less than the thickness of the recording materials are recorded in the bulk of photorefractive materials. In addition to the well known Bragg selectivity of the volume holograms, this geometric configuration influences the diffraction behavior of the reading beam. We have theoretically investigated this effect and experimental results are provided.