bluuebunny/crossref_metadata_2025 huggingface dataset:
Femtosecond Pulse Switching using the Soliton Self-Frequency Shift
Authors: Blow K.J. , Doran N.J. , Nelson B.P.
Published: February 2023

The ultra-high bit rate systems of the future will require the use of solitons in transmission to overcome the dispersion penalty associated with short pulses. Time division multiplexing (TDM) of these short pulses can be achieved by using passive couplers and delay lines as indicated in figure 1. However, demultiplexing presents a problem because of the very high switching speeds that are required. In this paper we describe a new method to achieve this demultiplexing passively. The scheme we are suggesting uses an optical fibre to create a wavelength division demultiplexed (WDD) system from a TDM input. This conversion is achieved by using the soliton self frequency shift[1].
The Raman response function of silica-core fibers - Effects on soliton propagation
Authors: Tomlinson W. J. , Stolen R. H. , Hawkins R. J. , Weiner A. M.
Published: February 2023

The effects of stimulated Raman gain are commonly analyzed in the frequency domain. For ultrashort (fsec) pulses, however, the spectral bandwidth of the pulse can be of the order of the Raman shift, or even larger, and this makes frequency domain analyses complicated and computationally inefficient. Alternatively, the Raman effect can be analyzed in the time domain, in which case the Raman gain is described by a time-dependent contribution to the intensity dependence of the refractive index.[1] In this paper we develop the Raman response function for silica-core optical fibers, and then use it for studies of the effects of Raman gain on the propagation of optical solitons in fibers, for both bright and dark solitons.
Spectral Shaping of Ultrashort Pulses and its Application to Pulse Compression and Dark Optical Solitons
Authors: Weiner A.M. , Heritage J.P.
Published: February 2023

Linear filtering is a widely applicable technique for manipulating spectral and temporal profiles of signals in any linear system. Powerful techniques for linear filtering of picosecond and femtosecond optical pulses have recently been developed; and as a result, synthesis of arbitrarily shaped ultrashort pulses has been achieved [1-5]. In this paper we describe two applications of ultrafast pulse shaping to nonlinear guided wave optics: (a) experimental demonstration of fundamental dark soliton propagation in optical fibers [6], and (b) extreme stabilization of optical pulse compression by stimulated Raman scattering [7, 8].
Nonlinear refraction and absorption of an InGaAs Single Quantum Well in an InGaAsP waveguide
Authors: Ehrlich J.E. , Goodwill D.J. , Neilson D.T. , Walker A.C. , Johnston C.I. , Sibbett W.
Published: February 2023

Semiconductor quantum-well structures can provide enhanced nonlinear effects compared to those observed in bulk material. The largest irradiance-induced refractive changes occur at wavelengths nearly resonant with the band edge or exciton absorption. If such a nonlinearity is to be effectively exploited in a waveguide configuration, the absorption due to the active quantum-well layers must be diluted to ensure sufficient transmission. Although this produces, all else being equal, a proportional drop in the effective nonlinearity (n2), it does permit operation at, or near to, the optimum wavelength where the figure-of-merit n
2
/α is maximized. In addition to the possible device potential of nonlinear optical waveguides, this configuration also permits investigation of the nonlinearity using light polarized both parallel (TE) and perpendicular (TM) to the quantum well. We present here measurements of nonlinear absorption and refraction, associated with electron-hole pair excitation, in an InGaAs Single Quantum Well (SQW) centered within a strip-loaded, non-absorbing InGaAsP waveguide.
Manipulation of quantum noise in a cavity atom system, observations and interpretation
Authors: Bachor Hans-A. , Hope D. M. , McClelland D. E.
Published: February 2023

The nonlinear coupling between two level atoms, in this case barium, and a near resonant cavity has been used to manipulate the properties of the fluctuations of the light inside and transmitted through this system. Experiments have shown that this system can be used to generate a beam of quadrature squeezed light with useful intensity and significant noise suppression (18% observed, 50 %inferred)1
Studies on the Dynanics of Optical Bistability Swithing in the Internal Fabry-Perot Cavity CdSxSe1-x-Doped Glass Waveguide Device
Authors: Peng Wen-Ji , Li Qing-Xing , Yu Zhen-Xin , Ning An , Mai Xu
Published: February 2023

Glasses doped with semiconductor microcrystalline CdS
x
Se1-
x
(10 nm – 100 nm in dimension) have recently attracted muuch interest due to their large third-order nonlinearities and fast response times. Jain and Lind have been reported the third-order nonlinear susceptibilities χ(8) of CdS
x
Se1-
x
-doped glasses were measured to be 10-9–10-8 esu in a degenerate four-wave mixing (DFWM) experiment and that the origin of the nonlinearity can be attributed to the generation of a short-live electron-hole plasma (band-filling effect)1. The nonlinear response of CdS
x
Se1-
x
-doped glass has been got to be about 3.5 ps2. So it has great potential to be used in developing high-speed and low-power nonlinear optical devices. Junji Yumoto8 observed the optical bistablility made using an external Fabry-Perot (F-P) cavity containing CdS
x
Se1-
x
-doped glasses with bistable-switching time of 25 ps. In this paper we report the observation of optical bistability of an internal F-P cavity structure single-mode waveguide device made of CdS
x
Se1−x-doped glass.
Statistics of Cross-Talk Noise in Holographic Data Storage
Authors: Gu Claire , Sornat Gregory , Hong John
Published: February 2023

Digital holographic data storage is becoming increasingly important because of its potential for optical memory systems with high storage density and fast parallel access. One of the important parameters of a digital system is its accuracy, which is usually characterized in terms of bit-error-rate (BER) defined as the probability of error for each bit. To determine the BER of a holographic storage system, one needs to know the statistics of the noise. There are several noise sources including cross-talk noise, scattering noise, shot noise, and thermal noise from the detector, etc. In this paper, we will concentrate on the discussion of the statistics of the cross-talk noise.
PRISM: Removing The Materials Bottleneck In Holographic Storage
Authors: Sincerbox Glenn T. , Hesselink Lambertus
Published: February 2023

The lack of a suitable recording material has long been the Achilles heel of holographic storage. In contrast to the other system components (such as SLM, laser and detector array) which are generally available, although they may not be optimized for this particular application, the ideal material has yet to be developed. As a result, after 30 years of on-and-off development, no commercial digital holographic storage system has yet been deployed To address this bottleneck, the PRISM (photorefractive information storage materials) consortium was formed in 1994 to focus on the development of a suitable recording material and to understand how storage system trade-offs are affected by each candidate material system.
Random Phase Diffuser Design for Holographic Storage
Authors: McMillen Deanna , Hudson Tracy D. , Kransteuber Amy S. , Gregory Don A. , Erbach Peter S. , Zabel Cynthia G.
Published: February 2023

Diffusers have frequently been used in holography to overcome the problem of limited dynamic range in the recording material. The limited dynamic range is even more of a problem when recording the Fourier transform of an image as is done when making matched filters for Vander Lugt-type correlators. A diffuser designed to be used when holographically storing matched filters must spread the energy over the recording material, but not diffuse it so much that information is lost. The key is to design a diffuser whose parameters are dependent on the recording material and not so much on the input.
Pseudorandom Codes for Volume Holographic Storage Application
Authors: Morozov V. , Johnson K. , Lahrichi A.
Published: February 2023

The capacity of volume holographic storage depends largely on the number of holograms that can be multiplexed in a volume material and retrieved with minimum crosstalk and noise. There are different techniques under development for hologram multiplexing: spatial, angular, and wavelength multiplexing [1,2,3]. Spatial multiplexing is promising technology since it does not require any beam steering devices. The orthogonal codes were proposed as a solution to minimize hologram crosstalk noise [3]. It was found later that for minimum crosstalk noise, in addition to being orthogonal, the hologram address codes must be symmetric or antisymmetric around the midpoint [4]. In contrast to these investigations, instead of orthogonal codes, we propose to use pseudo random codes for volume holographic storage applications such as: hologram spatial multiplexing, key words for associative memory, and memory based on image holography.
Phase-conditioning techniques for leveling of the reference beam intensity in orthogonal phase-encoded multiplexing for holographic data storage
Authors: Catrysse Peter B. , Bashaw Matthew C. , Heanue John F. , Hesselink Lambertus
Published: February 2023

Volume holographic data storage is a promising alternative to current surface storage technologies, since it can provide simultaneously large digital storage capacity, fast data transfer rates, and short access times [1]. This is achieved by storing multiple holographic data pages in a common recording volume, while retaining the ability to retrieve any individual page. Multiplexing of data pages can be performed either at one wavelength, using angular or phase-encoded multiplexing, or at different wavelengths, using wavelength multiplexing. This investigation focuses on phase-encoded multiplexing, which for example allows direct binary arithmetic operations on recorded pages and enables data encryption [2].
Digital Quasi-Phasematched Two-Color Nonvolatile Holographic Storage
Authors: Bjornson E.S. , Bashaw M. , Hesselink L.
Published: February 2023

One difficulty for the successful implementation of holographic data storage is having the ability to read data without affecting the data. Thermal fixing[1] as well as two-photon techniques[2] have been investigated as possible solutions. Reading data with a wavelength other than that which the data had been written is another viable alternative. Furthermore, choosing a reading wavelength that corresponds to a laser of a more favorable size, price, or ease of use could also be a benefit of such a system. Külich has previously investigated how to minimize the error induced due to reading and writing using different wavelengths by reading data with a spherical beam[3]. Psaltis et al. later introduced a formatting technique to allow a page to be read with a different wavelength by writing the page of data in pieces using several reference angles[4]. For digital data to be accurately read with an acceptable amount of mismatch, a three-dimensional mapping of the data must be applied to a system using this formatting technique. Optimization of such a system then requires the investigation of mismatch as a parameter effecting the diffraction efficiency.
Enhanced Nonlinear Optics Using an Atomic Local Oscillator
Authors: Jain Maneesh , Xia H. , Merriam A. J. , Yin G. Y. , Harris S. E.
Published: February 2023

Nonlinear optical mixing of existing laser frequencies to access portions of the spectrum where lasing action is not easily obtainable is common practice today. Although nonlinear solid-state media are available [1] for frequency conversion from just under 200 nm in the ultraviolet to about a few microns in the infrared, the generation of widely-tunable laser radiation in the mid-to-far infrared and VUV regions typically requires four-frequency mixing in atomic vapors. In the past, frequency conversion in atomic vapors suffered from poor conversion efficiencies due to the small magnitude of the third-order nonlinear susceptibility and the difficulty in phasematching. We demonstrate a method [2] for performing four-frequency mixing which overcomes both of these shortcomings, allowing efficient frequency conversion with moderate pump intensities.
Experiments on spatial solitons in saturating nonlinear media
Authors: Tikhonenko Vladimir , Christou Jason , Luther-Davies Barry , Kivshar Yuri
Published: February 2023

The spontaneous creation of spatial patterns in optical beams propagating in nonlinear media has been the subject of considerable research1. Of particular interest to us has been the formation of stable optical beams or spatial solitons since they may have some relevance to optical switching if the trajectory of those solitons is controllable. In a 3-D geometry bright soliton solutions for a Ken-law medium are unstable, however, bright solitons can exist when the nonlinearity saturates as is the case for many media such as Rubidium metal vapour used in our experiments. As a result it is possible to study 3-D bright soliton behaviour in such a medium and observe phenomena such as phase-dependent soliton attraction or repulsion2: phenomena which are analogous to those observed in Kerr-media.
(2+1)-D spatio-temporal solitary-wave dragging
Authors: Blair Steve , Wagner Kelvin , McLeod Robert
Published: February 2023

The (1+1)-D spatial soliton dragging interaction has been shown numerically to provide large gain with high gate contrast [1, 2] for optical switching applications, and is the spatial analog of temporal dragging in a fiber [3]. In order to retain the best features of both (1+1)-D spatial (short interaction lengths and ease of output state discrimination) and temporal (low energies) solitons, we must look at the dragging interaction between higher-dimensional spatio-temporal solitary waves, such as (3+1)-D light-bullets [4] or their reduced-dimensional counterparts: the (2+1)-D solitary waves in a waveguide. The numerical simulation of (2+1)-D solitary-wave dragging presented here is based upon a vector extension to the split-step algorithm using the exact linear propagation function including the full dispersion relation and nonparaxiality [5].
Phase-Insensitive, Single Wavelength, All-Optical Transistor Based on Cascaded Second-Order Nonlinearities
Authors: Wang Z. , Hagan D.J. , Kim S. , Van Stryland E. W. , Assanto G.
Published: February 2023

The resurgence of interest in cascaded second order nonlinearities[1,2] has resulted in several schemes for applying cascading in second-harmonic generating (SHG) crystals to optical transistor-like devices [3-7], Such devices allow a weak signal beam to impose a large amplitude modulation on a strong “pump” beam, through mixing in a χ(2) crystal. However, all of the devices reported to date require the pump and signal beams to be temporally coherent, as the process is strongly dependent on the phase between these two beams. There have been some suggestions[6,7] that type II phasematched SHG may remove phase sensitivity, but the devices proposed still require that the signal must be in phase with approximately half of the pump intensity. In this letter, we describe how one may properly exploit type II phase matching to produce a truly phase-insensitive all-optical transistor (AOT) based on second order nonlinearities.
Efficient Ultraviolet Light Generation by LiNbO3 Waveguide Quasi-Phase-Matched Second-Harmonic Generation Devices
Authors: Kintaka K. , Fujimura M. , Suhara T. , Nishihara H.
Published: February 2023

Waveguide quasi-phase-matched second-harmonic generation (QPM-SHG) devices are being studied as a promising candidate for realization of a compact short wavelength coherent light source. Efficient LiNbO3 waveguide QPM-SHG devices with ferroelectric-domain-inverted gratings for blue/green light generation have been reported so far [1,2]. Ultraviolet fight generation can give further advantages in many applications such as optical data storage, optical information processing, and optical sensors. In this paper, we present the first fabrication of domain-inverted gratings of ~2 μm period by applying voltage, and demonstrate efficient ultraviolet fight generation in LiNbO3 waveguide SHG device with the grating for 1st-order QPM.
From Dipolar to Multipolar Systems: Opening New Geometric and Quantum Dimensions in Molecular Nonlinear Optics
Authors: Zyss Joseph
Published: February 2023

The field of Molecular Nonlinear Optics1 has been seeded in the mid-seventies by the all pervading molecular diode template as exemplified by paranitroaniline derivatives exhibiting the now well recognized features of a rod-like dipolar structure with quasi-one dimensional intramolecular charge transfer between a single donor-acceptor pair via a delocalized π electron linkage. A highly consistent body of experiments in solutions, crystals and polymers as well as related models have come to reinforce the validity of this approach which has been further substantiated by a series of conceptual as well as application oriented developments. NLO measurements are now well acknowledged and currently used in Chemistry as sensitive probes of such basic features as intramolecular charge transfer or π-electron delocalization in conjugated systems whereas recent demonstrations of high bandwidth electrooptic modulation in polymer based modulators2 or low threshold near IR infrared parametric oscillation in molecular crystals3 evidence the application potential of the field. The existence of a large ground state dipole moment and the possibility to couple it to a poling electric field via a Langevin-Boltzmann distribution stands-out as the major cornerstone responsible for the development of the field. A two-level model pointing-out the difference between excited and ground state dipoles as a basic underlying parameter further strengthens the relevance of a dipolar geometry. However, such highly consistent interplay of dipolar models, experiments and technologies may have lead to ignore broader possibilities as recently recognized in the form of octupolar (see Fig.1) and more generally, multipolar systems4.
39.5% conversion of low power Q-switched Nd:YAG laser radiation to 266 nm by use of a resonant ring
Authors: Knittel Joachim , Kung A. H.
Published: February 2023

High power UV radiation is very attractive for many industrial applications including ultrahigh-density optical disk mastering, photolithography, material processing, marking, as well as for medical surgery and science1. While the excimer laser is the leading candidate for the UV source in these applications, fourth harmonic generation (FHG) from solid state lasers, with their compactness and availability of diode-laser pumping, offers a viable alternative to excimer lasers. For solid state lasers, efficient frequency conversion methods must be used to generate high UV power. For low power high-repetition-rate lasers the most promising approach is to use external resonant cavities.2-4 in this paper we report the use of a single resonant optical cavity to generate the fourth harmonic from the fundamental. The idea is to generate the second harmonic and the fourth harmonic both in one cavity consisting of mirrors that are highly reflecting at the second harmonic only. Hence the fundamental IR radiation is coupled into the cavity simply by a dichroic mirror. Energy is out-coupled from the cavity in the form of fourth harmonic UV radiation. The need for impedance matching is thus eliminated. This idea was put forward by Giordano and Matone for FHG from mode-locked lasers.5,6 in that case, in order to gain high conversion, it was necessary to match the length of the ring cavity to the IR laser length of 3.96 m with tight tolerance. The small beam size on the crystals led to thermal distortion and complex spatial mode pattern for the UV output. In this paper, we demonstrate that high UV conversion can be achieved from nanosecond IR pulses of energy in the mJ range using a single resonant ring cavity of arbitrary length and consisting of flat mirrors that are highly reflecting at the second harmonic. Using a Q-switched Nd:YAG laser running at 30 Hz with 213 mW of average IR power, we obtained 84 mW in the fourth harmonic at 266 nm. This corresponds to an internal IR to UV conversion of 39.5% (see figure 1). The output UV beam had a near-TEM00 mode with a 95% fit to a Gaussian profile. Enhancement of >65 by the ring over single pass UV generation was measured.
Multiple wavelength generation in a picosecond optical parametric oscillator based on noncritically-phase-matched LiB3O5
Authors: French S. , Ebrahimzadeh M. , Miller A.
Published: February 2023

The Ti:sapphire-pumped optical parametric oscillator (OPO) based on noncritically phase-matched LiB3O5 (LBO) has been shown to be a versatile source of high-repetition-rate picosecond pulses for the near-infrared1. It is capable of providing signal and idler output pulses with durations of 1-2 ps over the continuous wavelength range 1-2.5 μm. Here we present results that demonstrate that this system is also capable of directly producing visible picosecond pulses in the green spectral region.
Highly repetitive generation of picosecond pulses at 1.57 μm using an optical parametric generator and amplifier
Authors: Greiner U. J. , Schröder T. , Klingenberg H. H.
Published: February 2023

The generation of parametric fluorescence with picosecond pulses has recently enjoyed a revival. This is partly due to the availability of suitable pump sources, namely regenerative amplifiers, capable of producing picosecond pulses with pulse energies on the order of milli joules at repetition rates of several kilohertz. With such lasers it is easy to generate high power densities necessary for an efficient conversion in a nonlinear crystal1,2,3.
Cascaded Optical Nonlinearities: Microscopic Understanding of It as a Collective Effect
Authors: Khurgin Jacob B. , Lee S.J.
Published: February 2023

The third-order optical nonlinearities, whose potential for optical processing and switching has been understood for many years, have not found wide applications, for the simple reason that typical χ(3) is too small to make the devices based on it practical. Recently, however, a significant progress has been made on the way to change this unfortunate situation, by using cascaded second order nonlinear processes in order to achieve the effective third-order nonlinearity. This method, first realized in [1],[2] suggests the use of the parametric interaction between fundamental and second-harmonic waves in order to obtain effective χ(3) proportional to |χ(2)|2. More recently, a number of cascading schemes utilizing surface-emitting second-harmonic generation in a resonator have been proposed [3].
Computational Modeling of Ultrashort Pulse Propagation in Nonlinear Optical Materials
Authors: Goorjian Peter M. , Agrawal Govind P.
Published: February 2023

Recent progress in ultrafast technology has led to the generation of optical pulses as short as 8 fs. The propagation of such short pulses in nonlinear optical media requires new computational techniques in which the standard approximations such as the slowly-varying envelope approximation (SVEA) and rotating-wave approximation (RWA) are not made while using the Maxwell-Bloch equations [1]. Previous calculations, which used the finite-difference time-domain (FDTD) method, found that for a a Kerr-like instantaneous nonlinearity [2] significant differences can occur when the full vector Maxwell equations are used instead of the nonlinear Schrodinger equation. Recently, the FDTD method has been extended to the case of a homogeneously broadened two-level atomic system [3].
Non-degenerate two wave mixing in Kerr media
Authors: Skirtach Andrei G. , Simkin David J. , Boothroyd Simon A.
Published: February 2023

The analysis here applies to a nonlinearity with the refractive index represented by n=n0 + (n2′ + ın2″) I, where n2′ is the real (dispersive) and n2″ is the imaginary (absorptive) part of the nonlinear refractive index n2. An exact theoretical treatment has been given for the NDTWM including only the dispersive nonlinearity (n2″=0)1. This has been extended to include nonlinear absorption through a holographic or grating term2.
All-Optical Logic Gates Using SHG in Thin Film Waveguides
Authors: White W. R. , Dajani I. , Kopf D. C. , Alley T. G.
Published: February 2023

Several potentially useful all-optical modulators and switches have been demonstrated in fiber, channel, and planar waveguides [1,2,3,4]. Here we describe a unique all-optical switch within a planar waveguide that can be constructed to mimic various elementary logic gates. This switch is based on the generation of second harmonic light (532 nm) in a single guiding mode when fundamental frequency light (1064 nm) is launched into an optically modified silica waveguide in two different guiding modes. The desired gate is obtained by appropriately programming the waveguide during the optical modification process. Such an optical modification process requires that the waveguide is simultaneously illuminated with intense light containing angular frequencies ω and 2ω for 15-30 minutes. For this paper, we demonstrate both OR and AND logic gate functions that possess good signal to noise ratios, and we describe a means of achieving an XOR gate.
Two- wave mixing with partially coherent waves in photorefractive crystals
Authors: Yi Xianmin , Yang Changxi , Yeh Pochi
Published: February 2023

Two-wave mixing in photorefractive crystals in various configurations has been investigated extensively. Most of the previous works in this area are on wave mixing with mutually coherent waves.1 It is known that partial temporal coherence may affect the strength of the grating and the coupling.2 Two-wave mixing with partially coherent waves has been studied recently for the case of transmission grating interaction4-5. In this paper, we present the results of our theoretical and experimental investigation for the case of reflection grating interaction.
Critical Behavior of Femtosecond Nonlinearity of Metallic Indium on Melting
Authors: Zheludev N.I. , Popov S.V. , Shatwell I.R. , Gusev V.E.
Published: February 2023

We report on what is, to the best of our knowledge, the first observation of critical enhancement of optical nonlinearity in the vicinity of a phase transition. We studied the degenerate cubic optical nonlinearity of metallic indium on melting. We found that in the vicinity of the melting point this nonlinearity changes dramatically with temperature. So far nonlinear optical properties of liquid metals, where mercury is an example [1], have been studied only by second harmonic generation technique. No data on cubic nonlinearity of liquid metals or metals undergoing the phase transition are available. Recent observation of strong and very fast spin-flipping nonlinearity in bulk gold [2] stimulated us to investigate this nonlinearity in a liquid metal.
Nonlinear Optical Processes in Laser Modelocking
Authors: Sibbett Wilson
Published: February 2023

University of St. Andrews, U.K.
Theory of Stretched Pulse Laser
Authors: Namiki S. , Wong W. S. , Haus H. A.
Published: February 2023

Modelocked Erbium doped fiber ring lasers have been developed in many laboratories and commercial models are already available. The most common type is based on the soliton concept, a soliton-like pulse circulates around the ring. Modelocking is provided by a saturable absorber (e.g. quantum well)[1] or by Polarization-Additive-Pulse-Modelocking(P-APM)[2]. Solitons can be driven unstable by periodic disturbance of gain and loss. For this reason, soliton fiber ring lasers tend to generate low average power.
Exceptionally Large Third-Order Optical Nonlinearity of the Organic Charge-Transfer Complex
Authors: Gotoh T. , Kondoh T. , Egawa K. , Kubodera K.
Published: February 2023

Much effort has been devoted to a search for material having a large third-order optical nonlinearity sufficient to realize ultra-fast optical signal processing and optical computing etc. π-conjugated organic materials, especially conductive polymers such as polydiacetylenes, seem to attract a principal interest in this field because of their fast responces and large optical nonlinearities.1) Those known materials put origin of their optical nonlinearities on intramolecular electronic polarization. Our own scope is, however, that supramolecular electronic polarization is possibly an efficient origin of optical nonlinearity.2)
Optical Nonlinearities of Guest-Host-Polymer Structures
Authors: Singer Kenneth D.
Published: February 2023

Until recently, attempts to take advantage of the large second-order optical nonlinearities of certain conjugated organic molecules in devices were limited to neat crystalline materials, since the requirements for a noncentrosymmetric bulk phase could be met with molecular and polymeric crystals that happen to condense in a noncentrosymmetric point group.[1] The large dipoles that are often observed in these molecules made the growth of optical quality and robust crystals difficult. More recently, mixed systems consisting of the nonlinear optical molecules incorporated into polymer glasses, liquid crystals, and liquid crystal polymers have been investigated.[2] The difficulties in processing that are required to obtain optical quality materials are reduced. For second-order nonlinearities, an alignment process, such as electric field poling, is required to break the center of symmetry inherent in these materials. However, the reduction in number density and alignment attainable with realistic poling fields requires molecules with exceptionally large nonlinear optical susceptibilities in order to obtain bulk materials with nonlinear coefficients large enough to produce sensible devices.
Two-wave Mixing Gain in BSO with Applied Alternating Electric Fields
Authors: Krainak Michael A. , Davidson Frederic M.
Published: February 2023

Image amplification using photorefractive two-wave mixing is attractive since high gain and high signal-to-noise ratios are achievable using relatively low-power lasers. Huignard et. al. have achieved high gains in Bi12SiO20 (BSO) using the DC field and moving grating technique1. The disadvantages of this technique are the uniform illumination and external frequency shift requirements. Another option is the use of alternating electric fields as suggested by Stepanov and Petrov2. This technique has been demonstrated in BTO2 and GaAs3. It maintains the 90o phase shift between the incident fringe pattern and holographic grating required for image amplification, while allowing enhancement of the refractive index change via the external field. Other advantages include increased stability, no requirement for uniform illumination, and the avoidance of the electrode "shadowing" problem. In addition, the trap saturation regime (i. e. the maximum possible grating amplitude for a given material) can be reached at very high fields. The application of this technique to BSO has been suggested previously2,3,4, and preliminary results are presented here.
Thermal Effects in Ultrafast Photonic Switches
Authors: Weidman D. L. , Newhouse M. A. , Hall D. W.
Published: February 2023

The performance of a nonlinear device may be significantly altered by thermal effects. The heat generated by the absorption of power from the switching laser can induce thermal index changes which may overwhelm the photonic index changes. Here a model of these thermal effects is presented, and expressions for the relationship of thermal to photonic index changes are derived. Previous workers have considered heating due to a single pulse.1 Our treatment snows that, for the appropriate material and device parameter ranges, cumulative thermal build-up will be important in the envisioned high-data-rate systems. Using these results, we compare the potential performance characteristics of various materials, including experimental heavy-metal glasses which show large nonlinear effects.
Nonlinear Effects of Quantum Confinement Composite Materials in Planar Waveguide Structures
Authors: Tombrello Joseph F. , Inguva Ramarao , Bowden C.M.
Published: February 2023

Waveguide structures which utilize dielectric and quantum confinement nonlinearities in the guide or cladding are currently receiving great attention due to the potential for fast response times and switching1. We consider here the case of planar waveguide structures consisting of alternating layers of Gal-xAlxAs with varying aluminum concentration in a stepwise fashion to form the waveguide and the cladding, but with alternate layers of etched GaAs/Gal-xAlxAs multiple quantum well material as remote cladding. The latter thus form a remote cladding composite material for electronic quantum confinement in GaAs quantum dots. Using a generalization of a method discussed by Walpita2, the effects of the nonlinear cladding on the modes of the waveguide are studied as a function of the thickness of the nonlinear layer, the intensity of the electric field, and the change in the refractive index due to the variation in the aluminum concentration. The effects on the propagation of the electromagnetic field due to the nonlinear cladding are studied under the slowly varying envelope approximation using a variation of the Crank-Nicholson method3 to solve the nonlinear Schroedinger equation. Results will be presented for a model nonlinear (intensity dependent) dielectric constant with absorption.
Influence of material properties and particle geometry on the nonlinear optical performance of composite artificial Kerr materials.
Authors: Naylor David L.
Published: February 2023

Artificial Kerr materials consisting of suspended particles in a liquid host have been shown to exhibit nonlinear optical behavior.(1-4) If the suspended particles are spherical the suspension may display spatial variations in refractive index due to variations of the particle number density(1-3). It has been proposed(5) and demonstrated(4) that a suspension of anisotropic particles will exhibit birefringence due to alignment of the particles in an electric field. The latter effect is predicted to be faster than the former by a factor of order (Λ/a)2, where Λ is the grating period and a is the particle size.(5)
Design Considerations using Two-Wave Mixing Properties of Photorefractive Materials
Authors: Gilbreath G. C. , Davidson F. M.
Published: February 2023

Holographic recording in photorefractive materials1 is the subject of continued interest in the areas of image enhancement, real-time spatial light modulation and amplification. One of the properties of photorefractive media where energy can be transferred from a strong "pump" beam into a weaker "signal" beam2 has come to be known as "two-wave mixing". This property holds promise as a means for providing effective energy coupling for systems where efficient use of a fixed light budget is an over-riding design requirement, such as in a spacecraft laser communications link3.
Nonresonant Effects in CO2 Amplifier of Ultrashort Laser Pulses
Authors: Chelkowski Szczepan , Bandrauk André D.
Published: February 2023

Recently the amplification of subpicosecond pulses in CO2 resonant with 10.6 μm lasing transition 001→100 has been achieved for intensities up to 1012 W/cm2 [1]. This corresponds to Rabi frequency ≃ 10 cm-1 which becomes comparable to the detuning of various CO2 transitions usually neglected in standard calculations [2]. For instance, this Rabi frequency becomes close to the spacing between laser P(20) transition and R(18) transition equal to 32 cm-1 [1,3]. For higher intensities, the 9.6 μm, 001→020 transition should be taken into account, as well as the transitions 001→000, 001-002, etc. - see fig. 1.
Two-Wave Mixing in Saturable Absorbers and Ranging Applications
Authors: Boothroyd S.A. , Chrostowski J. , O'Sullivan M.S.
Published: February 2023

When two coherent light beams overlap in a saturable absorber, the materials refractive index is altered in phase with the light intensity distribution and a volume phase and/or absorption grating is created. A frequency shift introduced on one of the beams causes the fringe pattern to move. In materials with a finite response time, τ, a phase lag between the grating and the intensity pattern is produced and exchange of energy between the beams can occur.
Phase Conjugation by Stimulated Brillouin Scattering in CClF3 Near the Gas/Liquid Critical Temperature*
Authors: Hovis F. E. , Kelley J. D.
Published: February 2023

Stimulated Brillouin scattering (SBS) in CClF3 near the gas/liquid critical temperature has been found to have a small, frequency-tuneable (~150-300 MHz) shift.
Recent Developments in High Power Frequency Conversion
Authors: Eimerl D.
Published: February 2023

This paper reviews recent progress in nonlinear materials for frequency conversion of high power lasers to the UV-visible portion of the spectrum. Recent developments include some new data on old materials, the discovery of some new nonlinear materials, and development of systematic analytic procedures, together with appropriate databases, for the selection and optimization of materials for a particular application.
Femtosecond Nonlinear Optical Response of Modulation-Doped Quantum Wells
Authors: Knox Wayne H.
Published: February 2023

Modulation-doped quantum wells [1] offer a unique system to study femtosecond carrier interactions. Since the doping impurities are localized in the quantum well barriers, there is no contribution from impurity scattering when exciting carriers in the wells. In optical excitation experiments with semiconductors equal densities of electrons and holes are created. Therefore it is impossible to distinguish the separate effects of electrons and holes. Since in general the electrons and holes have different properties such as mass and phonon interactions we may expect that the scattering rates of electrons will be different than the holes. In addition, the separate contributions of the holes and electrons to the optical saturation signals have not been addressed before. We report new experiments [2] in which the femtosecond nonlinear optical response of modulation-doped quantum wells are studied for the first time and the results are compared to the previous results which have been obtained in undoped quantum wells.
Optical Nonlinearities of Composite Materials
Authors: Ricard D. , Hache F. , Roussignol P. , Flytzanis C.
Published: February 2023

The implementation of promising applications of nonlinear optics in the optoelectronics field depends on the availability of nonlinear materials possessing a large and fast nonlinear response. Research in this domain was for many years concentrated on homogeneous media, both inorganic and organic. Recently however, a few groups have studied the new properties originating from heterogeneous composite materials. Two processes may make them very attractive : local field correction and carrier confinement. We have, for example, investigated the nonlinear properties of metal colloïds (gold and silver) , whose linear properties had been extensively studied previously. Near the surface plasma resonance, their nonlinear response shows a dramatic enhancement. It is very fast (subpicosecond) and for volume fractions as small as a few 10−6 their Kerr susceptibility is of the same order of magnitude as that of CS2. This also allowed us to measure for the first time the Kerr susceptibility of these metals.
Composite Materials for the Enhancement of Optical Phase Conjugation
Authors: Neeves A. E. , Birnboim Meyer H.
Published: February 2023

Nonlinear optical materials are central to optical domain computing. A number of fast response time materials have emerged that have electronic nonlinear mechanisms in the picosecond and subpicosecond time scale. However, the small magnitude of the optical nonlinearity requires a high laser power density to utilize these materials. Flytzanis et al1 have demonstrated theoretically and experimentally a processs of self-enhancement of the effective x(3) from gold nanospheres. The electric field in the particle is increased at the plasmon resonance compared to the mean field in the suspension. This increased field in turn, enhances the intrinsic x(3) of gold.
Optical Response of a Composite Medium Consisting of Metal Particles in a Nonlinear Dielectric Host
Authors: Suits F. , Gibson U. J.
Published: February 2023

A composite medium consisting of small metallic particles in a dielectric host exhibits strong absorption at the surface plasmon resonance. This resonance causes the deep red color of gold colloids that has motivated several models of the optical properties of composite media. The Maxwell-Garnett1 theory is one of the earliest and simplest of these models, and it remains an excellent approximation to the dielectric function of composite media for small particles and small fill-fractions.
Effective Dielectric Function for a Random Distribution of Nonlinear Spherical Rayleigh-sized Microparticles
Authors: Leung K. M.
Published: February 2023

The problem of determining the effective dielectric function of an inhomogenous medium given the properties of its constituents has been of interest for quite a long time. A number of theories are available in the linear regime in the scientific literature, including the widely popular theories by Maxwell-Garnett,[1] and by Bruggeman.[2] There are also renewed interest with some new insights on this subject in recent years.[3] In these theories it is assumed that the particles as well as the host medium both behave linearly, that is the dielectric constants do not depend on the incident intensity.
Controlling the Second Order Nonlinear Optical Tensor Properties of Poled Films With Stress
Authors: Kuzyk M. G. , Singer K. D. , Zahn H. E. , King L. A.
Published: February 2023

The large electronic second order nonlinear optical susceptibilities of organic molecules can be built into bulk systems by imparting polar orientational order to an ensemble of nonlinear optical dopants. The noncentrosymmetric orientational order required for second order nonlinear optical processes in noncrystalline materials, such as molecule-doped liquid crystals and polymer glasses, has been demonstrated using electric field poling.[1] [2] [3] [4] The relationship between the second order molecular tensor susceptibility and the bulk tensor susceptibility of a polymer doped with optically nonlinear molecules has been recently calculated in the mean field approximation for poled materials under the influence of other bulk ordering forces [5] such as uniaxial stress. [6] Also, it has been previously shown that optical second harmonic generation can be a sensitive probe of molecular order.[7] In this paper, the tensor properties of the second order susceptibility of films poled under uniaxial stress in the direction of the poling field are determined. It is shown that both the magnitude and tensor properties of the second order susceptibility can be continuously varied with poling field and stress.
Evaluation of Third-Order Susceptibility of Vacuum-Deposited Polydiacetylene Thin Films
Authors: Kubodera K. , Tomaru S. , Kobayashi H. , Kanetake T. , Ishikawa K. , Koda T. , Takeda K. , Tokura Y. , Koshihara S.
Published: February 2023

Polydiacetylene (PDA) has high potential for use in nonlinear optical devices, such as optically gated switches and optical bistable devices, because it has large third-order nonlinearity due to one-dimensional conjugated π-electrons in its backbone chains. This material has the advantage of very fast response time and fairly small absorption loss. Nonlinear optical measurements have been performed for various sample forms, single crystals1) solvent-cast films, Langumuir-Blodgett (LB) films2), and vacuum-deposited films3),4). Among these, vacuum-deposited films are easiest to prepare because the process is dry and not time-consuming. However, the measured χ(3) values for films deposited by the usual method were not so large (≃ 1 × 10−11 esu) compared with those of single crystals1) and LB films2). This paper reports on the fairly large χ(3) value that has been observed in a highly-oriented epitaxial PDA thin film prepared by a successful vacuum-deposition method. This χ(3) value is larger than LB films and comparable to that of single crystals. To properly evaluate the χ(3) value, a third-harmonic generation (THG) measurement system with high accuracy has been set up.
Nonlinear Optical Absorption via Photon Avalanche
Authors: Kueny A. W. , Case W. E. , Koch M. E.
Published: February 2023

We report an investigation of a nonlinear optical absorption phenomenon observed in LaCl3 crystals doped with Pr. When these crystals are illuminated with a laser beam of 529 nm wavelength and intensity in excess of a certain critical value, the light is strongly absorbed. The laser radiation is resonant with a Pr3+ transition from the first excited state (3H5) to a high optical state (3P1), and absorption is accompanied by strong fluorescence output from 3p1 and 3p0 to several lower-lying levels. Since the resonant transition does not include the ground state, it is not expected a priori that any absorption should occur (see Fig. 1). This is an example of the so-called photon avalanche phenomenon1.
Polarization Properties of Nonlinear Optical Materials
Authors: Malcuit Michelle S. , Boyd Robert W. , Gauthier Daniel J. , Kauranen Martti , Tompkin Wayne R.
Published: February 2023

Nonlinear optical interactions can depend in a complicated manner on the state of polarization of the incident optical waves. For the case of isotropic nonlinear optical materials, the third order nonlinear polarization is expressed in terms of two parameters A and B describing the material system and can be written as1,2 (1) where

E
→

is the total field incident upon the medium. In this paper we present the results of investigations of the polarization properties of phase conjugation by degenerate four-wave mixing (DFWM) in fluorescein-doped boric acid glass and in sodium vapor utilizing the 3S1/2→6S1/2 two-photon allowed transition. We find that these two materials can be used for a vector phase conjugation. Vector phase conjugation (VPC) corrects for both wavefront and polarization distortions upon double pass through an aberrating medium.3
High-Gain Erbium-Doped Fiber Amplifier Pumped by 820 nm GaAlAs Laser Diodes
Authors: Suzuki Kazunori , Kimura Yasuo , Nakazawa Masataka
Published: February 2023

Er3+-doped fiber amplifiers are very useful for optical communication systems because of their characteristics of high gain, low noise, polarization insensitivity, and high saturation output.1,2 There are many pump-bands for Er3+-doped fibers, and in particular the 0.83,4, 0.985,6, and 1.487 μm bands have the potential for laser diode pumping. From among these pump bands, the 0.8 μm band is attractive because inexpensive high output GaAlAs laser diodes can be used. However, it has been thought difficult to obtain a high gain with this pumping line since because of the existence of excited state absorption (ESA)8. Recently, high gain amplification using a 0.8 μm band Ti:Sapphire laser was reported9. The optimum pumping wavelength was around 820 nm.
Spectral Gain Hole-Burning in an Erbium-Doped Fiber Amplifier with GeO2:SiO2 Core
Authors: Zyskind J. L. , Desurvire E. , Sulhoff J. W. , DiGiovanni D. J.
Published: February 2023

The gain saturation characteristics of erbium-doped fiber amplifiers, which are of importance for applications in optical fiber communications, will depend strongly on the relative importance of homogeneous and inhomogeneous saturation. We have recently reported low temperature spectral hole burning measurements in an erbium-doped fiber with an alumino-silicate core1. From these measurements the homogeneous linewidth was determined to be 11.5 nm. This is consistent with the homogeneous gain saturation observed for alumino-silicate fibers.2 For erbium-doped fibers with GeO2:SiO2 cores, on the other hand, inhomogeneous saturation effects have been reported.3