bluuebunny/crossref_metadata_2025 huggingface dataset:
4 GHz GaAs Photoconductive Mixer
Authors: Lam D.K.W. , MacDonald R.I.
Published: February 2023

Heterodyne detection, in which an intensity modulated optical signal is mixed with an electrical signal, has been demonstrated in various forms [1-3]. Of particular importance, an InP photoconductor has been used as a mixer through the gating of an electrical signal applied to the photoconductor by means of optically generated carriers. This type of mixer makes use of Auston [4] switches whereby the switching is introduced optically and the signal to be gated is introduced electrically. We refer to this type of mixer as "optically gated". In contrast the mixer reported here is "electrically gated". It works on the reverse principle in that the signal to be gated is introduced optically and the gating is achieved by varying the electrical bias of the mixer. The fact that the signals are introduced optically provides excellent isolation and subsequently permits the construction of broadband switching matrices [5] and the monolithic integration of photoconductive devices [6]. This mixer has been observed to operate at frequencies higher than 4 GHz, which is significantly greater than that reported in other heterodyne schemes. Also, a signal gain of 17 dB over that of conventional detection under a DC bias condition has been achieved.
OMVPE GaInAsP/InP crystal growth for integrated optics
Authors: Sugou Shigeo , Kameyama Atushi , Miyamoto Yasuyuki , Watanabe Chiaki , Furuya Kazuhito , Suematsu Yasuharu
Published: February 2023

The GaInAsP/InP organometallic vapor phase epitaxy (OMVPE) is one of the key techniques for development of semiconductor integrated optics for the wavelength range of 1.1-1.7μm, where integrated lasers [1] as well as quantum well structure devices [2] can be integrated. Although there have been reports on GaInAsP/InP OMVPE [3],[4], the growth condition in relations with sharp hetero-interface and p-type dopant are not clear.
Gallium Aluminum Arsenide/Gallium Arsenide Integrated Optical Repeater
Authors: Bar-Chaim N. , Lau K.Y. , Ury I. , Yariv A.
Published: February 2023

The goal of integrated optoelectronics is to monolithically integrate optoelectronic components with purely electronic components. In this paper we describe the demonstration of the monolithic integration of a laser, a transistor and a photodiode. The devices were fabricated on a semi-insulating (SI) substrate, which allows the devices to be electrically insulated from each other, and also reduces parasitics. The simple circuit configuration used here serves to illustrate the basic principles of operation of integrated optoelectronic circuits (IOEC) in general, and sheds light on the expected performance of more complicated circuits.
Nonsymmetric Mach-Zehnder interferometers used as low-drive voltage modulators
Authors: Jackel Janet Lehr , Favire F. J. , Johnson J.
Published: February 2023

We describe an integrated-optic Mach-Zehnder interferometer in which the branches are close enough to be strongly coupled and show that it behaves like an ordinary interferometer if the propagation constants for the two guides are sufficiently different. This design allows both low switching voltages and efficient coupling to the microwave driving circuit. Ti-diffused LiNbO3 prototypes have been built and tested.
1.3μm Avalanche Photodiodes Formed by Waveguiding in GexSi1-x, Strained Layer Superlattice
Authors: Temkin H. , Antreasyan A. , Olsson N. A. , Pearsall T. P. , Bean J. C.
Published: February 2023

Avalanche photodetectors are important components in the implementation of high bit-rate optical fiber communications. Ga0.47In0.53 As and Ge avalanche photodiodes considered for optical communications systems operating near 1.3μm suffer from an excess noise factor near the theoretical maximum. At the other extreme, Si avalanche photodetectors (APDs) have an excess factor near the absolute minimum. Unfortunately, the optical response of Si APDs is limited-to shorter wavelength, far below 1.3-1.5μm optimum spectral region for optical fiber transmission.
Planar Buried Heterostructure InP/GaInAs Lasers Grown Entirely by OMVPE with Semi-insulating Blocking Layers
Authors: Miller B. I. , Koren U. , Capik R. J.
Published: February 2023

Planar Buried-Heterostructure (PBH) lasers offer many advantages such as low threshold and ease of integration and have been used extensively in the 1.3–1.65 μm range for optical communications1,2. In most of this work the laser structure was grown by LPE including both the basic DH structure and the regrown p-n blocking layer. More recently many investigators have used various hybrid LPE-vapor phase techniques3-7 to grow these structures in order to increase planarity or yield. The desire to achieve these goals coupled with the difficulties associated with two step LPE growth would make g OMVPE a natural choice as a method of growth for the PBH structure and, in fact Nelson et al8 has reported an "all"-OMVPE grown PBH laser operating at 1.52 μm.
Vapor diffused optical waveguides in strontium barium niobate (SBN:60)
Authors: Eknoyan O. , Bulmer C. H. , Taylor H. F. , Burns W. K. , Greenblatt A. S. , Beach L. A. , Neurgaonkar R. R.
Published: February 2023

Metal diffusion in LiNbO3 and LiTaO3 is the most commonly used technique for fabricating waveguides for integrated optics.1 There has, however, been continuing interest in producing waveguides and modulators in other ferroelectric materials with higher electrooptic coefficients. One particularly attractive candidate is Sr0.6Ba0.4Nb2O6 (SBN:60),2 for which the r33 electrooptic coefficient at room temperature is more than an order of magnitude greater than that for LiNbO3 and LiTaO3. This paper reports use of vapor diffusion to fabricate planar and channel waveguides in SBN:60. This represents the first use of gaseous diffusion to fabricate waveguides in any ferroelectric material and the first waveguides in any material with such a high electrooptic coefficient. Electrooptic modulation has been demonstrated in channel waveguides, and a radioisotope technique has been used to characterize the sulfur diffusion process.
Origin and solution of finite extinction ratios in Ti:LiNbO3 directional coupler switches
Authors: McCaughan Leon , Choquette Kent D.
Published: February 2023

Ti:LiNbO3 directional coupler switches have consistently shown an extinction ratio in the −15 to −30-dB range but only rarely <−30 dB. This is illustrated by a set of 16 nominally identical directional coupler switches recently fabricated on a single substrate.1 An approximately random distribution of extinction ratios was measured ranging from −11.6 to <−35 dB. In addition, their response curves show nonideal behavior, such as unequal side lobes and nonzero voltage values for the maxima of the crossed state. We hypothesize and demonstrate that there is a common explanation for all these nonideal characteristics: random fluctuations in the effective index along the length of the diffused waveguide. Local random variations in the Ti concentration of the diffused waveguide could produce random fluctuations in their effective index.
Electron-beam lithography for formation of submicrometer gratings in semiconductor integrated optoelectronics
Authors: McInerney J. , Fice M. J. , Ahmed H.
Published: February 2023

Injection lasers and other components using microgratings promise to form important parts of integrated optoelectronic and all-optical systems. Of particular interest are low-order gratings for distributed feedback lasers, especially GaInAsP/InP devices emitting at 1.55 μm.1 Other potential applications include filtering and demultiplexing of guided-wave optical signals.
Integrated-optic sampler for transient rf and microwave signals
Authors: Ridgway Richard W.
Published: February 2023

High-speed sampling of electrical signals using integrated-optic devices has become a subject of great interest.1,2 Their small size, the ease of interfacing them with fast laser sources, and the high potential bandwidth of the electrooptic effect make integrated-optic devices ideal for high-speed and possibly low-cost sampling devices. The work reported here is devoted to development of the novel high-speed integrated-optic sampler shown in Fig. 1. The device consists of a series of electrooptic couplers fabricated along a coplanar rf stripline so that the electric field across each coupler is determined by the local voltage along the stripline and associated ground strip. A short optical pulse, which propagates in a direction opposite to the traveling wave electrical signal, passes sequentially through the electrooptic couplers causing a small amount of light to couple into the output waveguides and propagate to the optical detectors. The amount of coupled light is dependent on the local electric field. Each detector integrates the energy of the coupled optical pulses in the respective output waveguides to determine the associated instantaneous values of the electrical signal.
Guided-wave bistability via phase transitions in nonlinear liquid crystal claddings
Authors: Valera J. D. , Svensson B. , Seaton C. T. , Stegeman George I.
Published: February 2023

Liquid crystals have one of the largest intensity-dependent refractive indices due to both thermal effects (absorption) and molecular reorientation.1 When coated onto a thin film waveguide, they provide a very convenient nonlinear cladding medium which has already been used to demonstrate the existence of nonlinear guided waves2 and all-optical switching3 with different liquid crystal materials. In the experiment reported here we deliberately chose a liquid crystal material (K18) with a nematic-to-isotropic phase transition temperature just above room temperature and have observed bistability in guided-wave transmission.
Nonlinear optical coupling to planar GaAs/AlGaAs waveguides
Authors: Chen Y. J. , Carter G. M. , Sonek G. J. , Ballantyne J. M.
Published: February 2023

Nonlinear optical interactions in waveguides utilizing the material’s third-order nonlinear optical susceptibility X(3) is of interest for potential application, such as ultrafast optical signal processing1 and nonlinear optical switching.2,3 The X(3) can significantly modify the coupling via either a prism or grating between a radiative wave and guided mode.3 Previously, the experimental demonstrations have been limited to either poor quality waveguides4 or materials with a slow (thermal) response time.5 We report both linear and nonlinear optical grating coupling to good quality planar GaAs/AlGaAs waveguides and demonstrated nonlinear optical switching. The planar waveguides used in the experiments (1.7-µm GaAs on 3.0-µm AlGaAs) were epitaxially grown by metal-organic chemical vapor deposition (MOCVD) techniques. A 3300-Å period sinusoidal grating of ≃500-Å amplitude was fabricated on the GaAs surface using holographic lithography and ion milling. The coupling to the guided modes was observed by monitoring the intensity of the reflected collimated beam as a function of incident angle. The propagation length of each waveguide mode was also measured by monitoring the output intensity at the cleaved edge of the waveguide as a function of the propagation distance (by moving the incident beam away from the cleaved edge). A cw mode-locked Q-switched Nd:YAG laser operating at 1.06 µm, which produced a mode-locked pulse train of 150-ps pulses, was the light source. The peak intensity of the unfocused optical pulses at the center of the pulse train is The peak intensity of the unfocused optical pulses at the center of the pulse train ≃1 MW/cm2, and the duration of the train is ≃300 ns.
High-power semiconductor laser arrays
Authors: Streifer William
Published: February 2023

High-power semiconductor laser arrays are well known to emit at high-power levels of the order of 1 W. These devices consist of a number of parallel real-refractive or gain waveguides, which are sufficiently similar and closely coupled to phase lock. Thus the waveguide lasers exhibit some degree of coherence, and their outputs add In phase thereby radiating high power without excessive power density at the laser facet.
Self-consistent modal analysis of phase-locked semiconductor laser arrays
Authors: Katz Joseph , Marshall W. K.
Published: February 2023

Recently the eigenmodes of phase-locked semi-conductor laser arrays (supermodes) have been calculated by solving the wave equation of the arrays (for example, using the coupled-mode formalism1). Here we combine self-consistently the coupled-mode formalism with the rate equation solution,2 thus taking into account gain saturation effects3 and providing a higher accuracy modal analysis. The solution method Is outlined in Fig. 1. The need for this method of solution can be justified from the following argument. Even when we start with a nominally uniform array, the light intensity in the various channels will not be uniform but will vary according to the supermode profile. As a consequence, the carrier density—and thus the complex propagation constant—will be modified. The modified waveguide structure of the array will yield a modified set of eigenmodes, whose intensity distribution is different from the original one.
Telecommunications systems applications of integrated optics and integrated optoelectronics
Authors: Personick Stewart D.
Published: February 2023

A limited number of integrated optics and integrated optoelectronics devices are beginning to emerge from the research laboratory, and numerous other devices are being proposed or investigated by materials and device researchers. It is interesting to explore, somewhat speculatively, how devices of this sort might be employed in practical telecommunications transmission and switching systems. What do these devices bring to the table that would lead to reduced costs and/or new capabilities in providing telecommunications access and transport services? The competition is, of course, conventional electronics, which is not only an established technology but a rapidly evolving technology as well.
Ultrahigh-frequency modulation of InGaAsP lasers
Authors: Su C. B. , Olshansky R.
Published: February 2023

The design criteria of high-frequency lasers and the modulation performance of 1.3-μm vapor phase regrown buried heterostructure (VPR-BH) lasers are reviewed. The effect of nonlinear gain on dynamic response is discussed.
Monolithically integrable lateral PIN detectors
Authors: Jackson D. J. , Persechini D. L.
Published: February 2023

Monolithically integrable detectors are defined as detectors whose fabrication is completely compatible with the design rules used in the standard integrated circuit fabrication. An interdigitated electrode geometry permits both the ready integration of these detectors into electronic IC topologies and the use of a large detection area in conjunction with a low device capacitance. The large detector area improves the signal strength available for amplification, while the low capacitance extends the high-frequency bandwidth. To date, most interdigitated detectors reported in the literature are of the Schottky or photoconductive variety.1 Unfortunately, the low channel resistance between the interdigitated fingers produces a large Johnson noise contribution in these devices which increases linearly with the frequency.2 In comparison, the intrinsically high shunt resistance of a PIN diode enhances the SNR by limiting the Johnson noise contribution, thereby optimizing the detector dynamic range.
Advances In semiconductor integrated optics
Authors: Carenco Alain
Published: February 2023

As the use of single-mode fibers now successfully extends beyond the standard long-haul high-data-rate links due to the large interest in coherent transmission and the serious prospects of local area networks, there is an increasing need to develop improved or new guided-wave devices capable of launching, processing, and receiving optical signals. To satisfy the requirements of the expected applications, it is possible to consider discrete components based on semiconductor and dielectric waveguides in a hybrid form. But for obvious reasons, the natural tendency is to study monolithic integration of circuits.
Patterned Channel Waveguides on Printed Circuit Boards for Photonic Interconnection Applications
Authors: Hartman Davis H. , Howse James W. , Krchnavek Robert R. , Ladany Ivan
Published: February 2023

We report a process and material for fabricating patterned channel optical waveguides on conventional high speed electronics printed circuit cards. These waveguide structures were conceived as a means for achieving photonic clock or data distribution on printed circuit boards in very high (500mb/s< B <10Gb/s) synchronous systems.
Integrated Four-Channel Mach-Zehnder Multiplexer Fabricated With Phosphorous Doped SiO2 Waveguides on Si
Authors: Henry C. H. , Verbeek B. H. , Olsson N. A. , Orlowsky K. J. , Kazarinov R. F. , Johnson B. H.
Published: February 2023

Wavelength division multiplexing of optical signals is an efficient means to increase the information density per fiber. The purpose of this paper is to demonstrate and evaluate a multiplexer that is an optical integrated circuit, capable of mass production by conventional Si IC-processing. Here, we present a 4 channel multi/demultiplexer based on Mach-Zehnder interferometers, which has negligible reflections and low excess loss. The device is made from single mode channel waveguides of P-doped SiO2 on Si, which have a very low (0.05 dB/cm) waveguide loss for λ = 1.5 μm.
Very Low-Loss Proton-Exchanged LiNbO3 Waveguides With A Substantially Restored Electro-Optic Effect
Authors: Loni A. , De La Rue R.M. , Winfield J.M.
Published: February 2023

Proton-exchange is a low temperature process (140°C to 300°C) involving a chemical reaction between lithium niobate and acid in which lithium ions exchange with protons(1). The resulting waveguides have a step-like refractive index profile with Δne= 0.125 (λ= 0.6328μm)(2). There are a number of problems associated with proton-exchanged waveguides, namely relaxation of effective mode indices(3), d.c. drift effects(4), high propagation losses(5) and a substantially reduced electro-optic effect(6). Although methods have been developed to avoid, for example, the relaxation of effective mode indices(7), devices are still limited in their performance due to the reduced electro-optic effect and high propagation losses. For the first time, we report the possibility of fabricating waveguides with propagation losses reduced to 1/10 of the losses of 'as-exchanged' waveguides and an r33 value approximately 2/3 of the bulk value.
Low-Loss Proton-Exchanged LiNbO3 Waveguides With No Electrooptic Degradation
Authors: Suchoski P. G. , Abou el leil M. M. , Findakly T. K. , Leonberger F. J.
Published: February 2023

Due to their polarizing properties, power handling capabilities, and large index change, proton-exchanged (PE) LiNbO3 waveguides [1] could potentially out-perform their Ti-diffused counterparts in a number of device applications. Despite these distinct advantages, PE waveguides have found only limited use in functional devices and circuits. One reason for this lack of use is a prohibitively high insertion loss in previous PE waveguides. There have also been reports of degradation of the r33 electrooptic coefficient [2] and temporal instabilities [3] in PE waveguides.
New Polarization Scrambler Using Ti:LiNbO3 Rotating Waveplate
Authors: Smith David A. , Noe Reinhold
Published: February 2023

In coherent optical transmission systems using conventional single mode fibers, the received state of polarization (SOP) is unknown and changing [1]. Polarization scrambling of the transmitted signal [2] or the local oscillator [3] overcomes signal fading by forcing a signal to undergo very large polarization changes during each bit cycle. The power penalty is ideally 3 dB because on average the polarization match between signal and local oscillator is only one-half. If the transmitted signal is scrambled, only one scrambler is needed even if several subscribing receivers are used. One reported scrambler [2] has an integrated optical phase shifter as the active element and switches a certain class of input SOPs alternately between themselves and their orthogonal states. This particular scheme suffers from two notable deficiencies. First, some input SOPs are not scrambled at all. Second, a receiver bandwidth of many times the scrambling frequency is required to capture all spectral components produced by the scrambler, which amounts to an additional sensitivity penalty in a practical system.
Optical switch matrix with simplified nxn tree-structure
Authors: Okayama H. , Matoba A. , Shibuya R. , Ishida T.
Published: February 2023

The optical switch matrix is the one of the key elements in constructing optical switching systems. Many types of optical switch matrix architectures have been proposed1 to improve their characteristics and to construct devices with larger switch dimensions. However, since the substrate for fabricating the optical switch matrix is limited in size, the switching voltage of these structures was still relatively high. In addition, crosstalk characteristics degraded with increasing the number of output and input ports. The architecture wich can be obtained3 by simplifying the structure of tree-structure,2 wich we propose is one of the candidates for solving these problems. We report on the basic characteristics of this structure and some measured results from devices fabricated on LiNbO3 by indiffusion of Ti.
Single Frequency Pumped Doubly Resonant Integrated Optical Parametric Oscillator of Very High Efficiency
Authors: Suche H. , Sohler W.
Published: February 2023

Optical parametric oscillators (OPO’s) are tunable coherent light sources, most of them emitting in the near to middle infrared. Due to their extremely wide range of tunability [1] they are attractive for a variety of spectroscopic applications such as remote air pollution sensing [2].
Nonlinear Prism Coupling and Power Limiting in Ion-Exchanged Waveguides
Authors: Zhenguang H. , Srivastava R. , Ramaswamy R.V.
Published: February 2023

Glasses doped with Cd Sl-x Sex semiconductors form an important class of nonlinear materials in that they exhibit large third order nonlinearity with fast relaxation times, making them attractive for signal processing applications1. Nonlinear prism coupling in a sputtered glass waveguide in color glass substrates with a cw threshold of the order of 200mW has been reported2. K+-Na+ ion-exchanged waveguides in sodium rich Cd Sl-xSex doped glass have been fabricated3, and thermal nonlinear prism coupling under pulsed regime has been reported in ion-exchanged as well as sputtered glass waveguides [4,5].
Heterodyne Measurement of Optical Modulator Frequency Response
Authors: Dolfi David W. , Donald David K.
Published: February 2023

As the bandwidth of optical modulators increases, it becomes more difficult to measure their frequency response. A number of methods are currently in use, including direct detection using a fast, calibrated photodiode [1], the a.m. sideband technique [2], and an optical sampling technique [3]. The first of these is straightforward, but requires a calibrated photodiode with a bandwidth comparable to the modulator under test. The a.m. sideband technique requires non-linear behavior by the modulator. Further, it exhibits a second order dependence of the measured signal on the modulator response and drive voltage, leading to a decreased signal-to-noise ratio. The third technique requires the use of two r.f. sources as well as a source of fast optical pulses (e.g. a mode-locked laser).
Polarization Independent 4×4 Switch Matrix in LiNbO3 for Communicative and Distributive Switching
Authors: Granestrand P , Lagerström B , Svensson P , Thylen L , Stoltz B , Bergvall K , Olofsson H
Published: February 2023

Integrated optics switch matrices are expected to play an important role in optical space switching systems due to their ability to route information practically irrespective of its bandwidth and coding format (” code and frequency transparency”), in marked contrast to electronic switching networks. The integrated optics switches also offer the advantage of integration, as opposed to mechanical optical switches. Accordingly a number of integrated optics matrices have been reported1,2,3. However , all of these have been polarization sensitive, requiring interfacing to non-standard polarization holding fibers, and this can be considered a major factor in complicating systems applications. Ref4describes a polarization independent 1×16 switch in the tree structure employed below, however with strict fabrication tolerance on the switches. One reason for staying with polarization sensitive matrices has been the difficulty to combine integratability (reasonably low voltage -length product) with high yield for low crosstalk switch points. Here we report a matrix based on a switch point which combines these features by electronic tuning of its switching characteristics, relaxing fabrication tolerances5. The switch points are further arranged in a tree structure6,7which combines the capability for communicative as well as distributive switching with relaxed requirements on the crosstalk of each switching point. This is achieved at the expense of the number of switches: The 4×4 matrix reported in this paper (Fig 1) comprises 24 switches as opposed to the 16 switches of a crossbar structure, but the number of cascaded levels is only 4, as opposed to 7 in the crossbar case.
Optical Switching in Semiconductor MQW Optical Switch Due to Field Induced Reflection
Authors: Ravikumar K. G. , Kikugawa T. , Shimomura K. , Izumi A. , Arai S. , Suematsu Y. , Matsubara K.
Published: February 2023

High speed optical switches are quite essential in high bit rate transmission and high-speed exchange systems. Semiconductor MQW optical switch based on the electric field induced refractive index variation in MQW structure is a promising candidate for these systems, because of small device size and feasibility for photonic integrated circuits.
Polarization Independent LiNbO3 4×4 Matrix Switch
Authors: Nishimoto H. , Suzuki S. , Kondo M.
Published: February 2023

A strictly non-block matrix switch is a basic component in photonic space-division and time-division switching systems. A polarization dependent 8×8 LiNbO3 matrix switch has recently been reported1,2). However, maintaining polarization dependency for such switches, when insisting upon using polarization maintaining fibers or polarization controllers, seems to be a serious technical barrier for pratical use.
Photo-Electronic Bistable Device with Selectable Output Light Channels
Authors: Tashiro Y. , Kasahara K. , Hamao N. , Sugimoto M. , Yanase T.
Published: February 2023

Optical bistable devices are expected as memories or logic devices in photonic switching and processing systems. Optical bistable devices with multiple fan-out, particularly those whose output channels are externally controllable, will be very useful in a wide variety of applications as compared to conventional ones with fan-out = 1[1-3]. We proppose and demonstrate a new optical bistable device with selectable multiple light outputs, which basically is composed of a pnpn structure. The output in the induced light emission mode could be obtained in different waveguide channels by external electronic control at high speed.
Effects of Facet Reflection in a Monolithically Integrated Optical Device Consisting of a DFB Laser and an Amplifier/Modulator
Authors: Tada K. , Hashimoto J. , Nakano Y.
Published: February 2023

Distributed feedback (DFB) semiconductor lasers do not require cleaved facets in constructing the optical resonator, and therefore seem the best candidates for light sources in monolithically integrated optical devices and circuits. Integrations of a DFB laser and other optical components such as intensity modulators and wavelength tuners1-5 have recently been demonstrated. In such configuration, the reflection from the adjoining component affects the oscillation of the DFB laser, which provides the wavelength tuning capability. This, however, brings another instability to the laser, and in general seems to degrade the overall characteristics of the integrated devices, yet there has scarcely been theoretical studies treating this point quantitatively. Here we analyze static and dynamic properties of an integrated DFB laser with an optical amplifier/modulator, placing emphasis on the effects of the facet reflection.
Physics Technology and Potential Integration of Ultralow-Threshold Diode Lasers
Authors: Yariv Amnon
Published: February 2023

The advent of quantum well semiconductor crystal growth technology has made possible a new generation of optoelectronic devices. Chief among these are the quantum well laser and modulators and detectors based on the quantum confined Stark effect. The talk will illustrate how the basic quantum well physics gives rise to this new phenomena which are used in these devices. The talk will also describe actual devices which depend on the quantum well physics. These include the ultralow-threshold semiconductor laser, monolithic Q-switched semiconductor lasers, and a new generation of tunable p-i-n detectors.
Integrated High-Speed Ti:LiNbO3 Δβ-Reversal Switching Circuits
Authors: Veselka J.J. , Herr D.A. , Murphy T.O. , Buhl L.L. , Korotky S.K.
Published: February 2023

Substantial progress in the level of integration of optical switches has been made at several laboratories, with Ti:LiNbO3 crossbar arrays as large as 8×8 on a single chip having been demonstrated [1]. Typical operating speeds of the crosspoints of these switches are ~100 MHz. For some applications, such as optical time-division multiplexing [2], crosspoints operating at microwave frequencies are desirable. One promising approach to realize crosspoints for gigahertz rates is a traveling-wave Δβ-reversal directional coupler switch [3]. In this paper we report optical switches that consist of several of these high-speed crosspoints integrated on a single substrate. Critical to the performance of these integrated devices are the coupler and inter-coupler crosstalk levels. We present measurements of both up to multi-gigahertz frequencies.
Thermally Stabilized 1 X 4 Ti:LiNbO3 Waveguide Switch
Authors: Mekada N. , Seino M. , Yamane T. , Nakajima H.
Published: February 2023

Z-cut LiNbO3 waveguide devices are essential in high-speed optical fiber communication and photonic switching systems. To put them to practical use, they must be useable in wide temperature range. However, these devices usually have a large temperature dependency due to the thermally-induced pyroelectric charge on the z-cut surface. Electrodes on the highly-resistive SiO2 buffer layer makes charge distribution ununiform and results in an undesirable electric field on waveguides as we reported previously(1). Drive point voltage shifts with temperature and it degrades crosstalk. Another problem is the connection between fibers and waveguides. The conventional method using Si V-groove array provides thermally stable connection(2), but, there is often a large excess loss because of the imperfect matching between the waveguide and silicon end faces. The purpose of our research is to overcome these problems and make a thermally stable z-cut Ti:LiNbO3 high-speed switch with low loss. To solve the first problem, we formed a Si layer with appropriate resistivity between the SiO2 buffer layer and the electrodes to keep the surface-charge distribution uniform(1). We also devised a new method for attaching fibers to waveguides to make stable joints with low loss. We fabricated a low-loss, thermally stable 1X4 optical switch on z-cut LiNbO3 and tested it in a 512-Mbps optical time division switching system(3).
Beam Splitter in Ti:LiNbO3 using Coupled Waveguide Arrays
Authors: Peall R.G. , Syms R.R.A.
Published: February 2023

The coupling theory of Taylor and Yariv [1,2] pointed the way to a number of potentially useful devices using coupled waveguide arrays. In particular the use of multi-waveguide structures for power distribution and switching was proposed [3,4]. The assumptions of this theory are, however, violated for devices of practical interest and alternative strong coupling theories have therefore been developed [5-8].
Integrated-Optic Differential Laser Doppler Velocimeter with A Micro Fresnel Lens Array
Authors: Haruna M. , Kasazumi K. , Nishihara H.
Published: February 2023

The integrated-optic technology can provide rugged and compact devices/circuits for fiber sensors such as gyro [1,2] and LDV (laser Doppler velocimeter) [3,4]. In particular, the integrated-optic LDV seems to be promising for the practical use, because the Doppler-shifted signal light can be steadily heterodyne-detected via waveguides and fibers without influence of phase fluctuation caused by ambient temperature change. Very recently, we demonstrated the integrated-optic LDV pigtailed with a polarization-maintaining fiber, in which the whole heterodyne optics was integrated on a LiNbO3 [3,4]. This is called the reference-beam (one-beam) type of LDV. On the other hand, the relatively higher signal-to-noise ratio is in general obtained in the differential (two-beam) type of LDV [5]. The latter type has more often been used in practice for velocity measurement. In this paper, we propose and demonstrate a novel integrated-optic differential LDV consisting of a LiNbO3 waveguide device and a micro Fresnel lens (MFL) array.
InGaAsP Dual Wavelength Laser
Authors: Piccirilli A. B. , Dutta N. K. , Greuzka L. A. , Karlicek R. F. , Wynn J. D.
Published: February 2023

Semiconductor lasers emitting near 1.3μm and 1.55μm and fabricated using the InGaAsP material system are widely used as sources in fiber optic transmission systems. Wavelength division multiplexing (WDM) where light at different wavelengths are simultaneously encoded and propagated through the fiber is generally used to increase the capacity of existing fiber optic routes. Most WDM systems currently in operation use two separate laser chips as sources and use a multiplexer to combine the two outputs to a single fiber. This paper describes the fabrication and performance characteristic of a dual wavelength (1.3μm and 1.55μm) laser fabricated on the same chip.
Monolithic, Coherent, Two Dimensional Arrays of Grating Surface Emitting Lasers
Authors: Carlson N. W. , Evans G. A. , Ettenberg M. , Hammer J. M. , Lurie M.
Published: February 2023

During the last two years there has been rapid development in grating surface emitting (GSE) diode laser array technology. This has led to the recent demonstration of coherent monolithic two-dimensional arrays of 100 (10x10) distributed Bragg reflector (DBR) lasers.1 These arrays are attractive for optoelectronic integrated curcuit applications, since a large number of GSE lasers can be coupled by a network of waveguides on a single wafer. The use of DBR sections both as output couplers and feedback elements eliminates the need for cleaved facets, and, therefore, GSE arrays are not subject to failure due to catastrophic facet damage. In addition, the grating surface-emitting area can be made sufficiently large that far-field beam divergences of much less than 1° are produced. Since GSE arrays contain multiple emitting regions all separated by electrically independent gain sections, electronic beam steering is possible by suitable adjustment of the gain section currents.
A Folded-Cavity TJS Surface Emitting Laser
Authors: Takamori Takeshi , Coldren Larry A. , Merz James L.
Published: February 2023

Efficient surface-emitting lasers (SELs) are desired for applications in optical signal processing, communication, IC-interconnection and computing. Most SELs so far reported are of three different types: vertical cavity,1,2,3 in-plain lasers with external reflection mirrors,4 and those with 2nd order distributed Bragg reflectors.5 In this letter we demonstrate a new type of SEL with a transverse junction stripe (TJS) laser and an internal 45° mirror to direct the optical energy to the surface. A simple double-heterostructure laser with internal 45° mirror was reported earlier.6 In the present work, the combination of the folded-cavity structure with the TIS laser yielded a threshold current of 60 mA and an external differential quantum efficiency of 13% per facet, which represent a considerable improvement over earlier results, demonstrating that the proposed structure is very promising for the applications mentioned above.
Birefringence Analysis of a Lithium Niobate Polarisation Controller
Authors: Walker N G , Walker G R , Davidson J , Beaumont A R , Booth R C , Brain. M C
Published: February 2023

A lithium niobate polarisation controller has been fabricated. Novel techniques were used for detailed birefringence analysis and confirmation of near ideal behaviour. Endless polarisation control was successfully implemented using a simple, robust control algorithm.
Integrated-Optic Modulator Operating at Millimeter-Wave Frequencies
Authors: Ridgway R.W. , Wood V.E. , Seiler M.R. , Ruck G.T. , Whitacre R.T. , Busch J.R.
Published: February 2023

The modulation of optical signals at microwave and millimeter-wave frequencies is of much interest for fiber-optic communications and optical signal processing. The electrooptic effect, which induces an electric-field dependent change in refractive index, is known to operate at frequencies well in excess of 100 GHz. This change in refractive index can induce phase shifts in optical signals, and in appropriate configurations can also modulate intensity, frequency or polarization state of optical signals. However, the overlap of the microwave signal and the optical energy required for efficient electrooptic interaction is hard to achieve.
A Travelling Wave Semiconductor Laser Amplifier for Simultaneous Amplification and Detection
Authors: Gustavsson Mats , Karlsson Anders , Thylén Lars
Published: February 2023

Semiconductor laser amplifiers (SCLAs) have attracted considerable attention in recent years due to the potential of employing them as simple repeaters in fibre optic links, optical preamplifiers and in local area network type applications to compensate for insertion and power splitting losses [1], [2] and references therein. However, the versatility of the amplifier would be significantly increased if the amplifier could also perform a detecting function. This will permit this single device to perform a variety of functions such as simultaneously tapping and amplification of the data on a high speed fibre optic data bus, cf. [3], surveillance of input power and error rate in a repeater application and for signal extraction, self routing and feedback stabilization in photonic switching networks.
Efficient Acoustooptical Coupling of Guided to Substrate Modes in a Combined Acoustical/Optical Channel Guide
Authors: Hinkov V. , Nolte U. , Sohler W.
Published: February 2023

The acoustooptical coupling of guided to substrate modes in optical waveguides can find several attractive applications in integrated optics. Among them are a RF-spectrum analyzer of very simple construction, one- and two-dimensional beam scanners etc. Several papers have been published on this subject (see e.g. [1,2]); however, all experimental investigations demonstrated a very low coupling efficiency of some percent for watts of acoustical power.
A novel 3-dimensional ARROW by thin film patterning — Stripe Lateral Confinement of ARROW —
Authors: Baba T. , Kokubun Y. , Mera Y.
Published: February 2023

A novel 3-dimensional structure of ARROW by etching a very thin intermediate film into stripe geometry was proposed and demonstrated. This technique can be applied to the 3-dimensional stacked waveguide interconnection.
An Integrated InP/InGaAs Heterojunction Biploar Photoreceiver
Authors: Chandrasekhar S. , Campbell J. C. , Dentai A. G. , Joyner C. H. , Qua G. J. , Gnauck A. H. , Feuer M. D.
Published: February 2023

The rapid development of lightwave communications has created a demand for high-performance receivers for a variety of systems applications. For many of these applications, e. g. local area networks, cost is a primary consideration. It is expected that integration of the receiver components will eventually yield significant savings with little or no loss in performance. To date, most of the integrated receiver circuits that have been reported have combined p-i-n photodiodes with FET amplifier circuits1. Alternatives to the p-i-n/FET approach are a p-i-n or a phototransistor coupled to a bipolar amplifier circuit2. One motivation for the use of a phototransistor/bipolar configuration for integrated receiver circuits is better materials compatibility than p-i-n/FET circuits. A typical p-i-n photodiode structure consists of a lightly doped epitaxial absorbing layer on a heavily doped substrate. The FET amplifier circuit, on the other hand, requires a heavily doped channel on a semi-insulating substrate. In contrast, the phototransistor is functionally just a p-i-n photodiode integrated with a bipolar transistor in the common collector configuration and therefore can be fabricated from the same epitaxial layers used for a bipolar amplifier. Recently, Wang et al. have reported an all-bipolar photoreceiver for λ ≈ 0.85 μm consisting of a GaAs/AlGaAs heterojunction phototransistor (HPT) and GaAs/AlGaAs heterojunction bipolar (HBT) amplifier3. In this paper, we report, for the first time, an InP/InGaAs integrated receiver circuit which utilizes an HPT as the photodetector and a bipolar amplifier circuit. This circuit operates in the wavelength regions near 1.3 μm and 1.5 μm.
An Opto-Electronic Dynamic Random Access Memory (DRAM) Cell Utilizing a Three Terminal N-Channel Self-Aligned DOES Device
Authors: Taylor G. W. , Crawford D. L. , Simmons J. G.
Published: February 2023

The Double Heterostructure Opto-Electronic Switch (DOES) device has been demonstrated as a two terminal [1-3] and a three terminal [4] opto-electronic bistable switch having high and low conduction states with and without optical emission respectively and which can be switched on and off by both an optical and an electrical input signal. The third terminal permits xy addressing of the cell in a manner very similar to the Dynamic Random Access Memories (DRAMS) of silicon technology. Currently in electronic dynamic memories, the limitations on performance and density arise from the minimum ratio of cell to bit line capacitance (i.e. stored cell charge) that will still allow reliable sensing. Using the optical output of the DOES relieves this constraint because it is an active element whose output can be increased to the limits of the device power.
The Extinction Ratio in Optical Two-Guide Δβ Couplers*
Authors: Donnelly J. P. , Molter L. A. , Hopcraft G. S. , Smith R. E. , Haus H. A.
Published: February 2023

Conventional coupled-mode theory1 predicts that ideal switching with complete extinction can be achieved in any Δβ coupler with two antisymmetrically detuned sections of equal length provided that the total length is between one and three synchronous coupling lengths Lc. In practice, however, ideal switching can not generally be obtained using this mode of operation and other operating parameters, such as asymmetric detuning, must be employed to obtain an optimum extinction ratio2.
Overview of Optical Neural Networks
Authors: Psaltis Demetri
Published: February 2023

Holographic techniques for simulating the dense connectivity in neural computers are described. The potential roles of guided-wave optical devices in this area are addressed.
TE-TM Mode Splitter Using Branching Waveguides Made by Proton Exchange and Ti Diffusion
Authors: Goto N. , Yip G. L.
Published: February 2023

Optical TE-TM mode splitters have been formed with a directional coupler [1] and a Y-branch using electro-optic effects [2]. A polarization sensitive waveguide can be fabricated by PE technique because the PE process increases the extraordinary index ne alone. Hence, by using a combination of a PE waveguide and a TI one, TE-TM mode separation can be achieved. Fig. 1 shows a Y-branch TE-TM mode splitter on a Z-cut LiNbO3, where Arm 2 is formed by PE with post-annealing, whereas Arm 1 and the input waveguide are made by TI.
Fabrication and Characterization of Semiconductor Microlens Arrays
Authors: Diadiuk V. , Liau Z. L. , Walpole J.N.
Published: February 2023

The need for small, fast, high quality lenslets has become apparent over the last few years, with the development of diode laser sources, and in particular diode laser arrays. Since diode lasers typically have a beam divergence of a few tens of degrees, collimating the output beams generally leads to greatly improved far-field patterns. The preferred substrate for lenslet fabrication has been fused silica, on which both diffractive(1) and refractive(2) lenslets have been investigated with good results. However, the small index of refraction of quartz (n=1.5) can present problems with high aspect ratio features, such as the outer rings of Fresnel zone plates. In this paper we describe the fabrication and performance of ~f/1 microlenses fabricated on semiconductors, rather than quartz, wafers, where n~3. Binary Fresnel lenslets were fabricated in InP by wet etching, while InP and GaP were used to fabricate refractive lenslets by wet etching followed by mass transport.
Fabrication and Testing of X-Ray Lenses
Authors: Thomas N. L. , Bionta R. M. , Skulin K. , Makowiecki D. M.
Published: February 2023

Fresnel zone plates and phase plates were fabricated and tested with copper K-alpha X-rays (8 Kev, λ= 1.54 Å). Alternating layers of transparent and opaque materials are sputtered onto two substrates, sliced with a diamond or wire saw perpendicular to the coating, ground to a thin slab (~100 µm thick), and polished. The thin slabs are mounted in an X-ray test bed, illuminated with X-rays and scanned in the image plane with a detector and a moveable slit. The fabrication procedures and test results will be discussed.
Computer-Aided Alignment of a Grazing Incidence Ring Resonator For a Visible Wavelength Free Electron Laser
Authors: Hudyma Russell M. , Eigler Lynne C.
Published: February 2023

Computer aided alignment schemes have recently received much attention in the literature.1,2,3 At Rocketdyne, a computer-aided alignment system was developed to aid the alignment of Boeing's visible Free-Electron Laser (FEL).4
Optical Design and Optimization with Physical Optics
Authors: Lawrence George N. , Moore Kenneth E.
Published: February 2023

This paper describes implementation of optimization methods in physical optics modeling, similar to those used in geometrical lens design, but capable of treating the greater range of performance aspects which may be considered in a physical optics treatment. Physical optics, using a complex amplitude description of the optical beam and using Fourier diffraction propagation, provides a more accurate and powerful means of analysis than geometrical methods. Physical optics can more easily include nonlinear gain, unusual aperture shapes; a wider range of aberration types; mechanical and nonlinear optic phase conjugators; nonlinear optics effects such as stimulated Raman scattering, four-wave mixing, frequency doubling; optical resonators; etc.,.
An Enhancement of Conrady’s ‘D-d’ Method
Authors: Gintner Henry
Published: February 2023

Conrady’s ‘D-d’ method for predicting the optical path difference between wavefronts in two colors is a good approximation in many cases, providing a great deal of additional information with a minimum of additional computation. However, in some optical systems, especially high numerical aperture visual systems, Conrady’s method is frequently inadequate. In such cases, exact ray tracing in several wavelengths is used to determine chromatic aberrations. Because multi-color exact ray tracing is computationally more intensive and requires more data reduction than Conrady’s method, it is desirable to restrict its use. A modified differential ray trace method is presented which expands the usefulness of the Conrady method.
Design of Focusing Grating Coupler Construction Optics
Authors: Moore Kenneth E. , Lawrence George N.
Published: February 2023

Techniques for introducing compensating aberrations in the construction optics for waveguide grating couplers which are fabricated at visible and used at infrared wavelengths are discussed.