bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase-locked detection of running interference pattern in photorefractive SBN
Authors: Nestiorkin O. P. , Shershakov Ye. P. , Zel'dovich B. Ya. , Bogodaev N. V. , Ivleva L. I. , Polozkov N. M.
Published: February 2023

Holographic grating in a photorefractive crystal may be recorded due to the diffusion of electrons or their drift in external or intrinsic photovoltaic dc field as a result of illumination by a static interference pattern. Those traditional mechanisms are well studied [1]. Running interference pattern may be registered by the phase-locked detection in the externally applied ac field. That mechanism was realized in the paraelectric crystal Bi12TiO20 (BTO) [2,3]. In this work we have performed the phase-locked detection mechanism in the ferroelectric photorefractive crystal SBN:Ce.
Instability of spatial subharmonic under hologram recording in a photorefractive crystal
Authors: Nestiorkin O. P.
Published: February 2023

Wave mixing experiments in photorefractive crystals(PRC) have resulted in the observation of large number of interesting phenomena. Communications about spatial subharmonic generation were published in [1,2]. Subharmonic gratings with a wave vector q/n (n - integer) have been occuring during the illumination of PRC Bi12SiO20 by moving interference pattern with a wave vector q (Fig.1). Authors of [3] suggested the mechanism of generation of subharmonic at the expense of noise component amplification in the field of two pump waves. Amplification is caused by small off-Bragg vector Δq (see Fig.1). In this work we consider another possible mechanism of spatial subharmonic generation. By our opinion the particular mechanism which may lead to subharmonic generation is the following. Under illumination of PRC by interference pattern with intensity distribution I(x,t)=IO(1+0.5mexp[i(qx-Ωt)]+c.c) photoelectron concentration grating is generated there. That grating moves with the phase velocity v=Ω/q. Here IO is the average light intensity, m is a contrast of interference pattern, Ω is the frequency detuning of interacting beams. Fluctuation of space charge field ~El/2exp[i(qx/2-Ωt/2)]+c.c. causes the generation of photocurrent wave ~j1/2exp[i(qx/2-Ωt/2)]+c.c. That photocurrent wave has the same space-time structure as a space charge field wave and consequently may intensify the space charge separation under suitable phase relation between those two waves. If that intensification exceeds the Maxwell relaxation, the space charge field amplitude of subharmonic will increase. The optimum condition for such instability is realised when the photocurrent wave is under resonance with trap charge exchange wave (TCEW) [4].
A Self-Organizing Photorefractive Frequency Decoder
Authors: Saffman Mark , Benkert Claus , Anderson Dana Z.
Published: February 2023

We demonstrate a self-organizing photorefractive circuit which decodes optical signals. The circuit is a pair of ring resonators with photorefractive gain and cooperative and competitive mode interactions. When a spatially multimode beam containing two optical carrier frequencies is used as the pump, the resonator self-organizes such that each frequency oscillates in spatially separate rings. Initial results, with a two crystal BaTiO3 resonator, show a contrast ratio of better than 20:1 at the two outputs.
Characterisation and Modelling of Photo-Refractive Barium Titanate from 0 -100 MW/cm2
Authors: Barry N. , Damzen M. J. , Duffault L. , Troth R.
Published: February 2023

Many of the phenomena observed in barium titanate such as an intensity dependence in the absorption coefficient1, changes in the sign of the two-beam coupling coefficient2 and dark decay behaviour can be explained by the presence of secondary centres and simultaneous electron-hole photoconductivity3.
Pulsed Photoexcitation Studies in Photorefractive KNbO3
Authors: Ewart M. , Biaggio I. , Zgonik M. , Günter P.
Published: February 2023

The study of photorefractive gratings induced by short light pulses can give complementary information to wave mixing experiments performed with continuous wave lasers.
High Two-Wave-Mixing Gain in CdTe:V with an Optimized Low Frequency Alternative Electric Field
Authors: Moisan J. Y. , Gravey P. , Wolffer N. , Moine O. , Triboulet R. , Aoudia K.
Published: February 2023

The photorefractive effect is now extensively studied in semiconductors, in particular for applications to optical communications.
The Pyroelectric Response of Lithium Niobate Crystals Doped by Iron in the Condition of Optical Damage
Authors: Bogomolov A. A. , Dabizha T. A. , Grinkina A. E. , Chtchipakina O. S.
Published: February 2023

The fact of the detection of the anomalyous pyroelectric response, observed during the dynamical regime at laser iradiation applied with the density of 10 W · cm-2 A = 0,63 m on the lithium niotate samples doped by 0,5% of iron ingredient is announced in the work.
Photomicrodomain Light Scattering in Lithium Niobate Crystals
Authors: Lemeshko V. V. , Obuhovsky V.V. , Stoyanov A.V.
Published: February 2023

In the present work we report the investigation of a specific kind of photorefractive light scattering (PRLS) – so-called photomicrodomain scattering (PMDS). It appears during optical excitation of a z-cut of lithium niobate crystal and is shown in the form of scattering cone centered around the optical axis of the crystal.
Frequency response of an optical interferometer using photorefractive crystal
Authors: Ing R. K. , Monchalin J. -P.
Published: February 2023

Interferometers using photorefractive crystals are attractive for a number of practical applications by their characteristic of being adaptive to complex wave fronts [1]. Such wave fronts are found in applications such as the detection of the vibration or of the ultrasonic excitation of objects with rough surfaces, which cause light scattering and speckle [2].
Light Squeezing Via Subharmonic Generation in Photorefractive Crystals
Authors: Pavlik B. D.
Published: February 2023

Light-wave mixing in photorefractive crystals (PRO) have resulted in the observation of a large number of interesting phenomena.
Intensity dependent non-steady-state photo-EMF in crystals with long lifetimes of photoelectrons
Authors: Sokolov I.A. , Stepanov S.I.
Published: February 2023

We report results on non-steady-state photoEMF in photoconducting Bi12SiO20 crystal for different average illumination levels. Experimental dependencies of both cut-off frequencies, amplitude of the output signal, and position of its maximum vs light in ensity are explained by remarkable increase of the accepter concentration at high light intensity. Different parameters of BSO samples, including Maxwell relaxation time, lifetime of the photocarriers, their diffusion length, and concentration in the conductive band are estimated from the experimental data obtained.
Double Phase Conjugation via Thin Nonlinear Layers.
Authors: Safonov V. I. , Zel’dovich. B. Ya.
Published: February 2023

Double phase conjugation by photorefractive crystals is widely known [1]. In this report a new scheme of double phase conjugation is suggested. It consist of a lens and two thin nonlinear layers, situated approximately in the image plane of each other.
All-Optical Associative Memory using a Saturable Absorber and Photorefractive Crystals
Authors: Duelli M. , Cudney R. S. , Keller C. , Günter P.
Published: February 2023

An associative memory is a storage device in which an input set of data recalls another set of associated data. In particular, it has the property that an incomplete or distorted set can be used to retrieve the complete and correct version of a set of data that is most similar to the input.
Photo- and Radiation- Induced Polarization of Amorphous As2S3
Authors: O.I. Shpotyuk , M. Vakiv M. , A.P. Kovalsky , Q.Ya Mrooz , P.M. Kovalsky
Published: February 2023

Amorphous chalcogenide semiconductors (AChS) are characterized by unique possibilities to photoinduced changes of their physical properties, first of all optical absorption and refractive index [1].
Photorefractive Properties of the Layer of Dipole-Inactive Molecules
Authors: Trofimov A. S.
Published: February 2023

The paper deals with the computation simulation of structural transitions in molecular films
Linewidth Narrowing in Semiconductor Lasers Due to Self-Pumped Phase-Conjugate Feedback
Authors: Liby Bruce W. , Statman David , McInerney John G. , McIver John K.
Published: February 2023

The effects of optical feedback on semiconductor lasers have been studied for some time.
Detection of transient motion of a scattering surface by two-wave mixing in GaAs crystal.
Authors: Blouin Alain , Monchalin Jean-Pierre
Published: February 2023

The optical detection of transient surface motion has many practical applications which include the vibration monitoring of engineering structures ( aircrafts, power plants,...) and the detection of ultrasound produced by piezo-electric transducers or by pulsed laser excitation.
Photorefractive Effect with Combined Hole and Electron Shallow Traps
Authors: Duffault L. , Barry N. , Damzen MJ.
Published: February 2023

The presence of simultaneous electron and hole photoconductivity and secondary centres are now well-established features in photorefractive crystals such as barium titanate1,2,3,4.
Study of Defects Resulting from Polarization of LiNbO3
Authors: Belabaev K. G. , Kiseleva I. N. , Sarkisov V. K.
Published: February 2023

Summary not available
Influence of the Damage Resistant Impurities on the UV-Excited Luminescence In LiNbO3
Authors: Fischer C. , Woehlecke M. , Volk T. , Rubinina N.
Published: February 2023

In undoped LiNbO3 uv-excited luminescence in the visible is controlled by the stoichiometry of the crystal1, the yield of luminescen­ce increasing with the increase of Li2O content.
Wandering Excitations in a Photorefractive Ring Resonator
Authors: Saffman Mark , Montgomery Don , Zozulya Alexei A. , Anderson Dana Z.
Published: February 2023

The eigenmodes of a linear or nonlinear oscillator are found by imposing self consistent boundary conditions such that the oscillator field is equal to itself after one round trip of propagation.
Photorefractive Properties md electro-optic coefficients of Barium strontium titanante at near infrared wavelength
Authors: Wan S. W. , Abid Y. , Mhaifid T. , Jullien P.
Published: February 2023

A great deal attention is focalized on the photorefractive materials during the last two decades in order to obtain high optical nonlinearity at millwatt power level which make them particularly attractive for applications in optical signal processing, dynamic holography and optical phase conjugation, etc.
Growth of Perovskite - Type Crystals by the Crystal Vibration Technique
Authors: Hesse H. , Pankrath R.
Published: February 2023

Barium titanate and solid solutions of potassium tantalate-niobate are transparent ferroelectric materials showing very large electrooptic effects.
Photorefractive materials, effects and devices topical meeting Kiev -1993: Epitaxial Growth and Optical Properties of Bi12GeO20 SINGLE Cristalline Thin Films Deposited on (1102) Al2O2 Substrate by the Pulsed LASER Deposition (P.L.D) Technique
Authors: CHEVRIER V. , INAM A. , ETEMAD S. , HARRIS D. , LAUNAY J. C.
Published: February 2023

Photorefractive materials are of a significant interest for a variety of applications in optical signal processing.
Holographic Data Storage Devices Implemented with Photorefractive Materials
Authors: Hesselink Lambertus
Published: February 2023

Summary not available
Signal and Image Processing Using the Dynamics of Photorefractive Media
Authors: Anderson Dana
Published: February 2023

Summary not available
Title will be announced at the meeting
Authors: Fischer Baruch
Published: February 2023

Summary not available
UV Laser Induced Photocurrent in Oxygen Deficient Silica and Germanosilicate Glasses
Authors: Bagratashvili Victor N. , Tsypina Svetlana I. , Chernov Pavel V. , Rybaltovskii Aleksey O. , Zavorotny Yuriy S. , Alimpiev Sergey S. , Simanovskii Yaroslav O. , Dong Liang , Russell Philip St. J.
Published: February 2023

Germanium and silicon oxygen deficient centers (GODC and SODC) play a key role in the phenomenon of photosensitivity of glasses.1-4 The study of GODC and SODC and their photoreactions is proceeding vigorously,5-8 but the mechanisms of their phototransformations are far from being understood. The most popular mechanism of primary photoreaction of GODC and SODC is their photoionization.5,9,10 For SODC the two-step ionization channel was established,9,10 but for GODC the situation is more complicated. Unfortunately, up to this point there are only a few direct measurements of UV laser induced photocurrent in oxygen deficient glasses,9,11 which allow clarification of the mechanism of UV photoionization and its real part in the photodecomposition of GODC. We report the results of our direct photocurrent and photoluminescence studies of UV laser excitation and decomposition of defect centers in germanosilicate and silicate glasses.
Cladding-mode Resonances in Bragg Fibre Gratings: Depressed- and Matched-cladding Index Profiles
Authors: Hewlett S. J. , Love J. D. , Meltz G. , Bailey T. J. , Morey W. W.
Published: February 2023

A series of blazed, or tilted gratings were fabricated in both depressed-cladding (AT&T Accutether) and matched-cladding (Corning SMF-28) single-mode fibre. In each case, a phase mask was orientated to set the nominal blaze angle (i.e., the complement of the angle between the fibre axis and the etched lines in the mask) from 0° to 3°. The fibres were soaked in hydrogen at 2120 psi and 97.6°C for 15 hours to enhance their photosensitivity. Gratings were formed by exposing the fibre core to a 248 nm KrF laser for 5 minutes with a fluence of 130 mJ/cm2/pulse at a rate of 20 pulses/s.
Grating Michelson mirrors for optimised fibre laser performance
Authors: Sugden Kate , Bennion Ian , Byron Kevin , Rourke Howard , Davies Sandra
Published: February 2023

We report on the development of a novel use of a Michelson mirror based on fibre grating technology1 which gives flexibility in optimising the output from fibre pigtailed semiconductor lasers and rare earth doped fibre lasers. The novel Michelson mirror schemes described here can be used to optimise the output power from lasers and to filter the broadband spontaneous noise. Furthermore, in the case of external cavity semiconductor lasers, by using a displacement between the two gratings in the Michelson arrangement, FM to AM conversion could be induced and used to stabilise frequency shifts in these devices.
Fibre ring laser with fibre grating transmission filter
Authors: Farries M.C. , Reid D.C. , Zhang L. , Bennion I.
Published: February 2023

We report the first single mode fibre ring laser which uses a transmission fibre grating filter for selection of a single mode. Fibre gratings have been used in reflection mode in conjunction with a rare earth doped Sagnac loop to produce single mode operation1, but these are inefficient because a proportion of the internal laser power is reflected in the counter direction to the main lasing direction and this is absorbed in the isolator. The development of broad band chirped fibre gratings2 and transmission fibre gratings3,4 has enabled a ring unidirectional ring laser to be built using all fibre components with the exception of a fibre coupled optical isolator. The advantage of a fibre ring laser is that it provides an efficient narrow linewidth source which can be tuned across the erbium fibre amplifier gain bandwidth. We also show that the laser can be used as a sensitive strain sensor.
Photoinduced absorption and photobleaching in thulium-doped fluorozirconate fibers
Authors: Laperle Pierre , Chandonnet Alain , Vallée Réal
Published: February 2023

Over the past few years, thulium-doped fluorozirconate fibers have been studied for application as blue fiber lasers. Blue upconversion fiber lasers at 480 nm [1] and 455 nm [2] in a thulium-doped fluorozirconate fiber have been demonstrated at room temperature. Recently, a potentially important application of these fibers for amplification near 800 nm in the first telecommunication window has been reviewed [3]. In our work, we have observed a strong photodarkening of thulium-doped fluorozirconate fibers when pumped at 1.12 μm [4]. A similar behavior was reported in thulium-doped aluminosilicate fibers exposed to 1064 nm light [5]. We have also observed that it is possible to bleach a fluorozirconate fiber by exposing it to 488 nm radiation. These results have stimulated the present study on the formation of photoinduced absorption which may limit the efficiency of blue fiber lasers and other devices using thulium-doped fluorozirconate fibers.
In-Fiber Bragg Grating Devices for Telecommunications Applications
Authors: Huber David R.
Published: February 2023

The in-fiber Bragg grating is one of the most important developments in fiber telecommunications in this decade. Fiber Bragg gratings have been demonstrated that have reflectivity ranging from zero to almost one. Simple gratings have been demonstrated that have bandwidths ranging from a few GHz to many nanometers. Fiber gratings have found application in continuous wave and mode locked lasers, fiber dispersion compensation, pulse compression, fixed and tunable optical filters, add-drop filters and as demultiplexing elements. This paper will review telecommunication devices that have been realized with this key technology.
Perspectives in Glass Poling*
Authors: Brueck S. R. J.
Published: February 2023

Glass has long been established as the lowest loss and most manufacturable optical material. However, the low third-order nonlinearity of silica glasses and the absence of a second-order nonlinearity, forbidden by the inherent macroscopic inversion symmetry of amorphous materials, have resulted in many material investigations searching for a suitable complimentary nonlinear optical material. To date, no material has been found that combines a strong nonlinearity with the unrivaled optical transparency, manufacturing flexibility, enviromental stability, and opto-electronic and microelectronic integrability of glass.
Fiber Bragg Components in Filtering and Dispersion Compensation Applications
Authors: Hill K. O.
Published: February 2023

The photorefractive effect,[1] "photosensitivity", has great practical value in that it makes possible a family of novel passive fiber devices that have applications in optical communications and optical sensors.[2]
First-Principles Characterization of Structure and Properties of E’ Centers in Silica Glass
Authors: Kama Shashi P. , Kester John J.
Published: February 2023

The recent observations of second harmonic generation (SHG) of the infrared (IR) light in doped silica glass fibers,1,2 planar waveguides,3,4 and poled silica glass5 have attracted a great deal of attention in understanding the mechanism and origin of nonlinear optical (NLO) processes in a-SiO2. A number of possible mechanisms have been proposed6,7 to explain the experimental observations. However, in so far as these phenomenological models describe the observed SHG in fibers and waveguides, they do not address the microscopic mechanism of optical nonlinearity in silica glass. An understanding of the atomic-scale mechanism of NLO properties in a-SiO2 is important, not only for increasing our fundamental knowledge, but also for modeling new materials with yet enhanced optical susceptibility and faster response time for device applications. Here we present the results of first-ever ab initio studies of microscopic structure-NLO property relationships in systems containing free spin electrons, such as a-SiO2.
Creation of Optical Nonlinearity in Organic Polymer-Dye Films by Asymmetric Charge Injection
Authors: Berkovic G. , Cohen R. , Donval A. , Lavi B. , Yam R.
Published: February 2023

Bulk second order optical nonlinearity in organic polymers containing hyperpolarizable dye molecules is normally created by electrostatic field poling at elevated temperature, where the electric field induces a polar alignment of the dyes. In contrast to this approach, we have used asymmetric injection of electric charge into the polymer to create bulk nonlinearity in the polymer [1]. We show that the charge injection mechanism is fundamentally different from dipole alignment of the dye, and has both similarities and differences to poling of glass.
Laser Induced Pressure Pulse Probe of Charge Distribution in Thermally Poled Glass: Evidence of Dipole Polarization?
Authors: Kazansky P.G. , Smith A.R. , Russell P.St.J. , Yang G. M. , Sessler G. M.
Published: February 2023

In recent years, thermal poling of silica-based glasses has been shown to create permanent second-order nonlinearities (SON) of the order of 1 pm/V in bulk glass [1] and 0.2 pm/V in thermally poled optical fibre [2]. Despite the reproducibility and stability of the effect, the underlying mechanism has still not been fully elucidated.
A Model for Intensity Dependent Absorption and Photorefractive Effect in BaTiO3 Crystals
Authors: Brost G.A. , Motes R.A. , Rotge’ J.R. , Kim J.J.
Published: February 2023

Intensity dependent absorption and photorefractive effects have recently been observed at low intensities in barium titanate crystals [1, 2]. Also, there is some evidence that recombination centers other than iron impurities exist in BaTiO3 and contribute to the photorefractive effect [3, 4]. The model we present here assumes the existence of primary deep level traps such as iron and secondary shallow traps as shown in Fig. 1. We show that this model predicts the intensity dependence in BaTiO3.
Dynamic Holographic Interferometry and Phase Conjugation in the Ba2NaNbO15 and SBN Crystals
Authors: Kukhtarev N. , Semenets T. , Muraviev V. , Savchenko V. , Volyar A.
Published: February 2023

Dynamic holographic interferometry using selfdiffraction gyration was realized in SBN crystals, signal wave restoration after the multimode fiber by phase conjugation in Ba2NaNbO15 was demonstrated.
Optical Associative Memory Using a Multiplexed Hologram and Phase Conjugate Feedback
Authors: Lindsay I. , Aldridge N.B.
Published: February 2023

An associative memory is capable of associative recall, generating at the output the associate of the input, retrieved from its global memory store. There are two main classes of associative recall, namely autoassociation and heteroassociation. Autoassociative recall is the ability of a system to retrieve a complete memory element at output when presented with only a small arbitary fragment at input. Heteroassociative recall is the ability to retrieve again a solitary memory element at output, but now sharing no structural similarity with its associate input [1]. It is the purpose of this presentation to describe an all optical system, with accompanying experimental results, which demonstrated the ability to recall by autoassociation.
Holographic Light Scattering in Photorefractive Materials
Authors: Marotz J. , Ringhofer K. H. , Rupp R. A.
Published: February 2023

Photorefractive materials, for instance photorefractive crystals and photorefractive ceramics to which our main interest is dedicated, are of importance for optical storage applications. The dynamic-holographic recording process as well as the process of reading out a stored hologram, however, may be strongly disturbed by a simultaneous increase of scattered radiation. This “holographic scattering” has first been observed as early as 1971 by Amodei and Stäbler [1] in LiNbO3. In LiNbO3 it has further been investigated in references [2] to [9], in LiTaO3 in references [6, 10], in (Sr
x
:Ba1−
x
)1−
y
/(Nb2O6)
y
in references [11, 12], and in BaTiO3 in references [6, 7, 13, 14, 15, 16, 17]. The effect is believed to result from random gratings written by the beams illuminating the material and by light scattered from inhomogeneities of the material [3]. As a transient effect, amplification of the scattered radiation is typical. For the stationary state, however, amplification or decrease of the scattered radiation is possible [18]. The whole process is an exciting but complicated example of dynamical holography [19].
Analytic solution for photorefractive two beam coupling with time varying signal
Authors: Cronin-Golomb Mark
Published: February 2023

In this paper, we present an analytic solution for high gain two beam coupling in photorefractive crystals where one of the input beams may be time dependent. This is an extension of Heaton and Solymar's solution [1] for the two beam coupling transient which results when the signal beam is abruptly turned on at time t=0 and remains constant after that. Like the solution of Ref 1, we still use the undepleted pumps approximation; the extension involves allowing the signal beam to have arbitrary time variation.
Crystal growth of BaTiO3 and KNbO3 for photorefractive applications
Authors: Rytz D. , Wechsler B.A. , Nelson C.C. , Klein M.B.
Published: February 2023

BaTiO3 [1] and KNbO3 [2] are among the most intensively studied photorefractive materials. Both BaTiO3 and KNbO3 are cubic perovskites at their respective growth temperatures and undergo the same sequence of cubic-tetragonal-orthorhombic-rhombohedral phase transitions upon cooling. The phase transitions occur at 132, 10 and −90 °C for BaTiO3 and at 435, 223 and −50 °C for KNbO3. At room temperature, tetragonal BaTiO3 and orthorhombic KNbO3 are both ferroelectric with 6 and 12 possible orientations for the spontaneous polarization, respectively.
Possible iron and associated centers responsible of the photorefractive effect in BaTiO3
Authors: Michel-Calendini F.M. , Godefroy G.
Published: February 2023

A recent paper by Klein and Schwartz (1) discuss the photorefractive effect mechanisms (PRE) in commercial BaTiO3 samples in terms of Fe2+ and Fe3+ impurities. The results of various experimental techniques (RPE, beam compling, absorption) lead them to conclude that the usual two level model involving the Fe2+ to Fe3+ conversion is sufficient to explain PRE. As their interpretations invoke molecular orbital calculations relevant to iron centers in various perovskite hosts (see ref.2 for instance), a more complete study of the electronic structures of possible centers responsible of PRE in BaTiO3 is presented in this paper. To this end, we report in figure 1 the electronic levels of Fe2+, Fe3+ ions trapped in tetragonal BaTiO3 as well as the ones relevant to neutral and single ionized oxygen vacancies. The calculations are based on the MS-Xx method as described in ref. 2. They assume that iron substitutes exactly Ti4+ in its tetragonal site, without additional relaxation or distortion of the lattice around the impurity ; near a Vo site, Ti4+ is assumed to be displaced by about 0.2A° towards Vo. We concentrate now on the possible centers responsible of PRE.
Theoretical active impurity levels of Cr and Mn for photorefractive effects in BaTiO3
Authors: Moretti P. , Michel-Calendini F.M.
Published: February 2023

The band model1) is commonly used to describe photorefractive effects, assuming that optically excited carriers (electrons or holes), from band gap impurities levels, migrate to the dark regions of the crystal where they are trapped. If iron has been put forward to give predominant photorefractive species in BaTiO3, either in intentionally doped2) or in as said pure crystals3), others 3d transitions elements could play a part in these mechanisms, as they tend also to behave as deep centers, and can significantly affect the electronic properties of the material involved.
Effects of Iron concentration and valence on the photorefractive Properties of BaTiO3
Authors: Schunemann P. G. , Temple D. A. , Hathcock R. S. , Warde C. , Tuller H. L. , Jenssen H. P.
Published: February 2023

Photorefractive characterization of iron-doped BaTiO3 (5 to 1000 ppm) under as-grown, oxidized and reduced conditions suggest that Fe2+ and Fe3+ ions may not be the dominant photorefractive species.
Photoconductivity in Photorefractive SBN
Authors: Hathcock R. S. , Temple D. A. , Warde C. , Neurgaonkar R. R.
Published: February 2023

Czochralski grown SBN:Fe and SBN:Ce crystals have been studied by photoconductivity and temperature dependent conductivity in order to understand the nature of trapping centers in these materials.
Differences in the photorefractive behaviour of various B.G.O. crystals
Authors: Besson C. , Jonathan J.M.C. , Pauliat G. , Roosen G. , Launay J.C.
Published: February 2023

Various applications such as optical data processing or laser beam stearing have been developed using Bismuth Silicone Oxyde (Bi12SiO20) or Bismuth Germanium Oxyde (Bi12GeO20) However, much remains to be done to understand in which way the chemical composition and the structure of the crystals, changes their photorefractive behaviour. This is why our two labs developed on the one hand the growth of BGO crystals (with various chemical compositions, dopants and annealing conditions) and in the other hand, the optical determination of their photorefractive parameters.
Influence of Polarisation State and Absorption Gratings on Photorefractive Two-wave Mixing in GaAs
Authors: Walsh K. , Hall T.J. , Burge R.E.
Published: February 2023

In recent years, study has been made of the photorefractive effect in semi-insulating GaAs, both Cr- doped(1,3,4) and with EL2 centres(2). The motivation for examining this effect has been the faster response time of GaAs compared with other photorefractive materials such as Bi12SiO20 or BaTiO3 (5). Also, its operation at near infra-red wavelengths with semiconductor lasers opens up possibilities of incorporating photorefractive materials in integrated optical systems(6).
Photorefractive Two-Beam Coupling with Polarization-Flip in Gallium Arsenide
Authors: Chang Tallis Y. , Chiou Arthur E.T. , Yeh Pochi
Published: February 2023

We present observations of polarization-flip photorefractive two-beam coupling in a GaAs crystal, using both cw and pulsed Nd:YAG lasers. Here, two s-polarized waves are coupled to give rise to a p-polarized wave, and vice versa, using the birefringent nature of the photorefractive grating. Our experimental data agrees well with the recently developed theory which is generalized to all cubic electro-optic crystals.
All-Optical Regenerator Using a Semiconductor Laser Amplifier in a Loop Mirror Configuration
Authors: Eiselt M. , Pieper W. , Weber H. G.
Published: February 2023

A decision gate is reported for all-optical data retiming, operating at 1 Gbit/s, polarization independent and enabling simultaneously wavelength conversion up to 60 nm.
Sparsely-Filled Densely-Wavelength-Division-Multiplexed Networks
Authors: Midwinter J. E.
Published: February 2023

It has been clear for some time that optical fibre transmission systems have the potential to carry vastly greater amounts of traffic than they are currently used for. For example, in Fig.1, we show typical values for the insertion loss of a 50km fibre section in the 1500nm window and overlay it with an approximate representation of an Erbium Doped Fibre Amplifier (EDFA) gain spectrum. The combination promises transparency over a spectral window of about 35nm width, corresponding to a spectral bandwidth of approximately 4700 GHz. Dispersion in the fibre seems likely to limit the data rate transmitted over long distance circuits (say 1000km) to the region of 1 Gbit/s unless optical equalisation techniques are employed or special low dispersion (dispersion shifted) fibres are employed. Moreover, it is clear that at the terminations of any long haul system, the signals will be reconverted to electrical form. Two questions have thus presented themselves to us. How can this awesome potential of the fibre be better used and, at the same time, how can such higher capacity signals be routed and distributed through a complex multinode network in a flexible manner without returning them to the electronic domain? This latter question raises key points about how the signals will be multiplexed in the optical domain.
Optical Fiber Interconnection Links for High-Speed Switching and Computer Systems
Authors: Nakagami Takakiyo
Published: February 2023

Among the various optical interconnection technologies being researched today, optical fiber interconnection is one of the most practical for near-term applications. [1] It is very effective for solving the recent problem of data transfer bottlenecks in advanced switching systems and computers. [2]-[4] The merits of optical transmission, including wide bandwidth, immunity to electromagnetic interference, ground-isolation capability, and small cable size, also favor in such short-distance applications. Since their circuit boards and units usually have parallel I/O interfaces, multi-fiber parallel transmission has the advantages of compatibility to the conventional system designs as well as the capacity for high overall transmission throughputs. This paper discusses the technical issues associated with the optical fiber interconnection links mainly focusing on parallel links and touching upon recent developments in Japan.
Photonic 2×2 Packet Switch with Input Buffers
Authors: Spring Jonathan , Tucker Rodney S.
Published: February 2023

We demonstrate a self-routing 2×2 photonic packet switch with two fibre-loop input buffers that provide output contention resolution. The switch operates with asynchronous traffic.
Variable Optical Delay Line for Frame Synchronizer Photonic ATM Switching System
Authors: Ozeki Takeshi , Shimizu Yukio , Sharma Manish , Ibe Hiroyuki
Published: February 2023

A variable optical delay line for use in a frame synchronizer for photonic ATM switching systems is analyzed and its operation was confirmed experimentally for the first time.
Photonic ATM Cross-Connect Node Based on Cell Aggregation and Compression
Authors: Bostica B. , Cinato P. , Calzavara M. , Gambini P. , Puleo M. , Vezzoni E.
Published: February 2023

The telecommunication networks are evolving towards an always growing dimension and transport capability and to meet the requirements of the future broadband services they will have to be able to provide a great flexibility. The Asynchronous Transfer Mode (ATM) seems to be a key technique for switching and transport, to satisfy broadband and flexibility requirements.
GaAs/AlGaAs FET-SEED Receiver/Transmitters
Authors: Woodward T. K. , Lentine A. L. , Chirovsky L. M. F. , Focht M. W. , Freund J. M. , Guth G. D. , Leibenguth R. E. , Smith L. E. , D’Asaro L. A. , Laskowski E. J. , Pei S. S.
Published: February 2023

A critical step toward the realization of optical interconnect between or on electronic chips at the high-density level is the monolithic combination of electronic and optical devices. Toward this end, we have pursued the monolithic integration of GaAs multiple quantum well (MQW) modulators with GaAs-based doped-channel heterostructure field-effect transistors (HFETs). Since the MQW pin device functions as both a modulator and a detector, its presence permits optical input and output. We refer to this integrated device structure as a field-effect transistor self-electro-optic effect device (FET-SEED). Such an approach permits the realization of complex circuits (the level of complexity being yield limited) with optical input and output anywhere on the circuit.[1, 2, 3] We have previously described the structure and fabrication of these devices.[1, 3]
Low-Responsivity GaAs/AlAs Asymmetric Fabry-Perot Modulators
Authors: Woodward T. K. , Tell B. , Knox W. H. , Stark J. B. , Asom M. T.
Published: February 2023

Absorption-based light modulators are attractive because they can be made compact and in high densities, operating with light normal to the plane of the device. The intrinsic power dissipation of such a modulator is simply the absorbed optical power, which (neglecting radiative recombination) must be dissipated in the device. However, most of the total dissipation in electrically-driven multiple quantum well (MQW) modulators operating with light incident normal to the device plane is non-intrinsic, resulting from motion of photo-generated carriers in externally applied electric fields. For example, in a pin MQW device biased to 5 V, motion of photo-generated electron-hole pairs through the total potential= V + V
bi
deposits about 6.3 eV of energy, 5 eV of which is non-intrinsic. Minimizing the overall dissipation in these devices is important, because it ultimately determines the packing density and the maximum optical input power.
Present and Future of FDM Photonic Switching
Authors: Yasui Tadahiko , Uemura Aritomo
Published: February 2023

An FDM (Frequency Division Multiplexing) photonic switching system is a very promising system in that it is only feasible by photonics. It utilized enormous bandwidth of lightwave and is independent of transmission methods and bit-rate. This system seems more suitable for the coming broadband age than ATM-based systems because in future they will provide us with an infrastructure for more flexible and lower cost telecommunication networks.
Signal transmission characteristics of a photonic FDM multichannel selector
Authors: Habara Keishi , Sasayama Koji , Okuno Masayuki
Published: February 2023

Photonic frequency-division-multiplexing (FDM) systems have been widely studied recently to achieve large-capacity optical networks. We have previously proposed a multi-frequency-channel selector[1] using a coherent optical transversal filter[2]. This paper describes frequency characteristics and transmission characteristics of an experimental 8-ch multi-frequency-channel selector.
Dilated Acousto-Optic Switches for Low Crosstalk Wavelength Routing in WDM Systems
Authors: Smith D. A. , d’Alessandro A. , Baran J. E.
Published: February 2023

The goal of dense wavelength-division multiplexed (WDM) networks is to to expand the capacity of high throughput optical networks through parallel processing in the wavelength domain. Thinking of wavelength slots as independent information-bearing channels, one must find means to add or drop wavelengths into the network or, more generally, to overlay independent routing patterns for each separate wavelength channel on top of a single physical fiber network. By far, the integrated acousto-optic filter (AOF) [1] is the most sophisticated component for wavelength-selective filtering and switching in wavelength-routed optical networks. The unique feature of the AOF is its ability to filter or route many wavelength channels simultaneously, unlike other single-state filters, such as the Fabry-Perot and Mach-Zehnder cascade. In this paper we demonstrate a technique to construct very low crosstalk 1×2 and 2×2 AO switches by means of switch dilation [2]. Dilation allows one to obtain nearly ideal switch performance by cascading filter subcomponents, in such a way as to reduce first-order crosstalk to second order. The price paid is switch complexity.
Electrically Actuated Nanomechanical Integrated Optical Switches
Authors: Pliska P. , Lukosz W.
Published: February 2023

We report on modulation, directional switching, and deflection of guided waves actuated by nano-mechanically induced effective-refractive-index changes ΔN. The integrated optical (IO) devices are actuated electrically. No electrooptic materials are required; glass waveguides on silicon are used.
A Time Domain Approach for Avoiding Crosstalk in MINs
Authors: Qiao Chunming , Melhem Rami , Chiarulli Donald , Levitan Steven
Published: February 2023

Large photonic space switching networks can be built from 2 × 2 directional couplers (called switches hereafter) with Multistage Interconnection Network (MIN) architectures. These switches can cause problems such as crosstalk and optical path loss. Studies have shown that based on the current characteristics of these switches, crosstalk limits the size of a network more than path loss does [1, 5].
Ultrafast nonlinear refraction in an active MQW waveguide
Authors: Fisher M A , Wickes H , Kennedy G T , Grant R S , Sibbett W
Published: February 2023

Future practical ultrafast (>100 Gbit/s) all-optical switching and information processing systems will need nonlinear optical devices which combine high speed of operation with moderate optical power requirements. Recently a large above-bandgap ultrafast optical nonlinearity has been observed in active semiconductor waveguides driven at the material transparency current1, 2. The origin of the new nonlinearity is not yet clear. Dynamic carrier effects may contribute, as may a resonantly enhanced optical Stark effect, not normally observable in passive waveguides because of high interband absorption. In the case of active waveguides at transparency this optical loss is balanced by gain from the electrical pumping.
All optical regenerator using a semiconductor laser amplifier in a loop mirror configuration
Authors: Eiselt M. , Pieper W. , Weber H. G.
Published: February 2023

All optical repeaters, which retime optical data signals, are essential components for photonic switching systems. In general these regenerators operate as follows. The optical data signal is combined with an optical clock signal (synchronized with the data signal) and both are coupled into a decision gate (AND gate). Decision gates based on a SEED (data rate 5 kbit/s [1]), on a bistable Fabry-Perot amplifier (data rate 140 Mbit/s [2]), on a bistable three electrode DFB laser diode (data rate 200 Mbit/s [3]) and on a nonlinear Sagnac interferometer switch (data rate 3 Gbit/s [4]) have been demonstrated. In this paper we report on a new kind of decision gate based on a semiconductor laser amplifier (SLA) in a loop mirror (SLALOM) configuration. This decision gate was operated at 1 Gbit/s. It exhibits a contrast ratio of better than 20 dB, no polarization dependence for the data signals, and it enables simultaneously all-optical wavelength conversion over a wavelength range of about 60 nm. As compared to the nonlinear Sagnac interferometer switch, it requires optical powers for switching, which are about three orders of magnitude lower. It is very compact and offers the advantage of a possible integration on a chip.
Optical Crossbar Switch with Semiconductor Optical Amplifiers
Authors: McAdams L. R. , Gerrish A. M. , Kalman R. F. , Goodman J. W.
Published: February 2023

Semiconductor optical amplifiers (SOAs) have a number of attractive properties for use in photonic switches. SOAs offer nanosecond switching times, extinction ratios in excess of 40 dB, and small signal gains of approximately 15 dB. In addition they can be monolithically integrated, and thus can potentially be fabricated in volume and used in large switch matrices. Here we report on our recent demonstration of an 8×8 optical crossbar switch based upon discrete SOAs. Other authors [1-3] have reported on SOA-based optical switches at the device level. Our work focuses on the demonstration of the technology at the system level. This demonstration is a significant step towards the widespread use of SOA-based optical switches because it provides a testbed for exploring and identifying the relationships between device parameters and system performance requirements. A block diagram of the optical crossbar switch is shown in Figure 1. The switch is constructed in a modular fashion and consists of optical, digital, analog, and computer modules. Figure 2 shows a photograph of the completed optical crossbar switch.
Optoelectronic Hybrid Multi-Stage Interconnection Network
Authors: Jiang Jie , Tietgen Karl Heinz
Published: February 2023

Two new approaches to modularize the multi-stage interconnection network and a new design concept for optoelectronic hybrid realization are presented. This concept is particularly appropriate for applications of self-routing switching networks and high-speed interconnections of processors.
Practical Demonstration of a Free-Space Optical Crossbar Switch
Authors: White H. J. , Brownjohn N. A. , Stace C. , Proudley G. M. , Walker A. C. , Taghizadeh M. R. , Robertson B. , Barrett C. P. , Birch M. J.
Published: February 2023

A single stage optical crossbar switch has been developed as part of a collaborative project entitled Optically Connected Parallel Machines (OCPM). The aim of this project is to develop electronically controlled, free-space optical systems capable of inter-connecting large numbers of advanced electronic processors and arbitrarily switching high bandwidth signals between them. The implications of this high performance communications technology for parallel computing architectures is being analysed by way of simulations and technology demonstrators. The optoelectronic interconnect system consists of an electronically addressed spatial light modulator positioned at the centre of a single stage optical crossbar configuration formed with holographic and bulk optical elements. This paper describes the development of the optical crossbar switch and both its current and predicted performance.
Lossless and Low Crosstalk InP Based 2×2 Optical Switch with Integrated Optical Amplifier
Authors: Kirihara Toshio , Ogawa Mari , Inoue Hiroaki , Nishimura Shinji , Ishida Koji
Published: February 2023

A lossless and low crosstalk optical switch is most desirable for large scale photonic networks. To realize such a switch, a traveling-wave amplifier is integrated into the slip waveguide of a carrier-injection type optical single-slip structure(S3) switch. Fiber-to-fiber lossless and low crosstalk (an ON/OFF ratio as high as 40dB) are demonstrated in a 2 X 2 cross-bar optical switch that has integrated 4 amplifiers and 8 Y-branch optical switches.
Functional Photonic Switching Device by Vertical and Direct Integration of Six Heterojunction Phototransistors and Two Laser Diodes
Authors: Noda Susumu , Shibata Kimitaka , Ahamady Vahid , Sasaki Akio
Published: February 2023

Photonic switching device composed of six heterojunction phototransistors and two laser diodes is developed. The device optically-controlled multilevel latch and erase functions and multilevel flip-flop functions.
Ultrafast, Multi-THz Frequency Conversion of a Picosecond Pulse Train Using a 1.5 μm MQW Semiconductor Laser Amplifier
Authors: Schnabel R. , Pieper W. , Ludwig R. , Weber H. G.
Published: February 2023

The femtosecond nonlinear gain dynamics in semiconductor laser amplifiers were used for 3.8 THz frequency conversion of 30 ps pulses. Applications for femtosecond optical gating may be possible.
Optoelectronic Logic Arrays Using the Light Amplifying Optical Switch (LAOS)
Authors: Geib K. M. , Feld S. A. , Beyette F. R. , An X. , Alhokail H. , Hafich M. J. , Robinson G. Y. , Wilmsen C. W.
Published: February 2023

The design and fabrication of optoelectronic arrays poses a new set of problems not encountered with individual devices. These include smaller feature size, tighter tolerances, a bus structure, planarization and step coverage issues. The later two issues are particularly problematic with vertically integrated devices, such as the LAOS, since the mesas are greater than 3 μm high. This paper discusses these design/fabrication issues and illustrates some solutions.
Advances in SEED Based Free Space Switching Systems
Authors: Lentine Anthony L.
Published: February 2023

Advancements in architectures, network control strategy, optical and
mechanical system design, laser source design, SEED array design that
have led to advances in optical switching system demonstrations are
discussed.
5-Stage Embedded-Control EGS Network Using FET-SEED Smart Pixel Arrays
Authors: McCormick F. B. , Cloonan T. J. , Lentine A. L. , Sasian J. M. , Morrison R. L. , Beckman M. G. , Walker S. L. , Wojcik M. J. , Hinterlong S. J. , Crisci R. J. , Novotny R. A. , Hinton H. S.
Published: February 2023

We demonstrate a 5 stage, fully interconnected 32×16 switching network using smart pixel 2×1 switching nodes. A 15input, 16 output system configuration was operated at 50 Mb/s per channel.
Low-Responsivity GaAs/AlAs Asymmetric Fabry-Perot Modulators
Authors: Woodward T. K. , Tell B. , Knox W. H. , Asom M. T. , Stark J. B.
Published: February 2023

We find that proton-implanted pin AlAs/GaAs asymmetric Fabry-Perot multiple quantum well modulators exhibit suppressed photocurrent responsivity while maintaining good modulation performance. We attribute this to a beneficial effect of the cavity resonance on an otherwise broadened exciton transition. We find photocurrent responsivity in devices implanted to 1 × 1013cm–2 to be reduced by a factor of 57 from the unimplanted case. Asymmetric self-electro-optic effect devices having significant gain (28) and output contrast ratio (8) are demonstrated.