bluuebunny/crossref_metadata_2025 huggingface dataset:
Art Music of Albanians in Kosovo: First steps towards initiation and development phase division
Authors: Kryeziu Breznica Rreze
Published: February 2023

The development of Albanian Art Music in Kosovo started after World War II and it shared the same fate as other countries situated in the Balkans. Art Music of Kosovo has gone through different political, social and economic situations as all other countries which were part of the then ex- Yugoslavia (1918-1991). However, the impact was stronger due to the beginning of the last war in Kosovo (commencing in 1990, almost a decade before the war), a war that made ten mandatory years desertion of the cultural and educational life of Albanians in Kosovo. The above-mentioned political and social circumstances, as well as other dramatic changes within Kosovo have negatively affected the development of Albanian Art Music in Kosovo, which, from my perspective, was and is a neutral sphere of identity, as it started in a vacuum – i.e., an emptiness, in terms of its activities which did not exist before 20th century. This article, strives to identify the existence of Art Music in Kosovo whose development when observed, acts as evidence just how great an achievement can be reached over a very short period of time. Its main purpose is to highlight the first steps towards its initiation and also the growing European music tradition within a society which was isolated for centuries.
Experiences of family carers of older people in marginalised communities in Namibia
Authors: Ananias Janet , Keating Norah
Published: February 2023

Namibia’s lengthy colonial history and current high levels of inequality foreshadow care in the context of poverty and marginalisation, and within families that are diverse and whose care capacities are poorly understood. Focus group interviews with family carers of older people in two marginalised communities provide insights into their experiences of care. We highlight three findings: first, contexts of care perpetuate and entrench marginalisation; second, care is not widely shared within families, raising questions of what it means to ‘do family’; and, third, care has negative consequences for carers and their families, foreshadowing generational replication of carer exclusion.
Intraocular composition of higher order aberrations in non-myopic children
Authors: Hughes Rohan P. J. , Read Scott A. , Collins Michael J. , Vincent Stephen J.
Published: February 2023

This study examined anterior corneal, internal ocular, and total ocular higher order aberrations (HOA’s), and retinal image quality in a non-myopic, paediatric cohort. Anterior corneal aberrations were derived from corneal topography data captured using a Placido disk videokeratoscope (E300, Medmont International), and whole eye HOA’s were measured using a Hartmann-Shack wavefront sensor (COAS-HD, Wavefront Sciences). The associations between HOA’s and age, sex, refractive error, and axial length were explored using correlation analyses. Data for 84 children aged between 5 and 12 years (mean ± standard deviation spherical equivalent refraction (SER), +0.63 ± 0.35 D; range 0.00 to +1.75 D) were included, and an eighth order Zernike polynomial was fit for 4 and 6 mm pupil diameters for both the anterior corneal and total ocular HOA’s, from which internal ocular HOA’s were calculated via subtraction following alignment to a common reference axis (pupil centre). Internal ocular HOA’s were of greater magnitude than previous studies of adolescents and adults, however partial internal “compensation” of HOA’s was observed, which resulted in reduced levels of HOA’s and excellent retinal image quality. Few significant associations were observed between HOA’s and age, SER, and axial length (all correlations, p > 0.001), and there were minimal sex-based differences (all comparisons, p > 0.005). Coefficients for vertical coma (C3−1 and C5−1) and spherical aberration (C40 and C60), were most strongly associated with the visual Strehl ratio based on the optical transfer function (VSOTF), which indicated that the absolute magnitudes of these Zernike coefficients have the greatest impact on retinal image quality in this paediatric cohort. These findings provide an improved understanding of the optics and retinal image quality of children’s eyes.
Tailored chromatic diffraction efficiency of double-layer single-relief blazed gratings
Authors: Engelhardt Lia , Stumpf Daniela , Brunner Robert
Published: February 2023

“Wavelength selectivity” is an important intrinsic property of diffractive optical elements that offers significant application potential. Here, we focus on tailored wavelength selectivity, the controlled efficiency distribution into different specific diffraction orders for selected wavelengths or wavelength ranges from UV to IR using interlaced double-layer single-relief blazed gratings composed of two materials. Dispersion characteristics of inorganic glasses, layer materials, polymers, nanocomposites, and high-index liquids are taken into account to investigate the impact of especially intersecting or partially overlapping dispersion curves on diffraction efficiency in different orders, providing a guideline for material choice depending on the required optical performance. By selecting appropriate combinations of materials and adjusting the grating depth, a wide variety of small or large wavelength ranges can be assigned to different diffraction orders with high efficiency that can be beneficially applied to wavelength selective functions in optical systems also including imaging or broadband lighting applications.
Design of non-linear optical fibres.
Authors: Holmes M. J. , Payne F. P.
Published: February 2023

Future transmission systems may use third-order non-linear effects in single-mode fibres to provide optical signal processing functions [1]. Low cost, compact and reliable implementations of non-linear systems will use semiconductor pump lasers. The operating life of such lasers and the consequent system reliability is improved by reducing the power consumption. The subject of this paper is the optimisation of the fibre waveguide structure so as to obtain the maximum non-linear effect for a given pump power.
Crystal Growth and Optical Characterization of a New Organic Nonlinear Material: L-N-(5-nitro-2-pyridyl)leucinol
Authors: Shigemoto T. , Ukachi T. , Takahashi M. , Komatsu H. , Sakaguchi Y. , Kawahara T. , Sugiyama T.
Published: February 2023

In the past several years there has been increasing interest in organic nonlinear optical material for a number of applications, such as second-harmonic generation (SHG), frequency mixing, electro-optic modulation, and optical parametric oscillation.
Anisotropy and Second Order Nonlinear Optical Properties Induced by Photoisomerization of Azo Dyes in polymeric films
Authors: Dumont M. , Sekkat Z.
Published: February 2023

In order to obtain second order nonlinear optical properties in doped (or functionalized) polymer films, it is necessary to orient the polar dopant molecules (poling process) and to insure a long term stability of this orientation. Other applications of organic films, such as writing polarization gratings by photoinduced anisotropy, deal with alignment of molecules (i.e. an anisotropic but centrosymmetric distribution).
Nonlinear Optical Study of the Fullerene Molecules
Authors: Qian Shixiong , Song Jie , Wang Gongming , Li Yufen
Published: February 2023

Since the discovering of C60 as a "magic" cluster in a carbon-cluster beam and the interesting speculation of the soccerball structure by Smalley group several years ago[1], many theoretical and experimental works have been done to confirm the proposed structure and to study the physical properties of C60, the so-called Buckminsterfullerene[2–4].
Near-Resonance, Time-Resolved Degenerate Four Wave Mixing Studies for Thin Films of C60 and C70 Fullerenes Using Femtosecond Optical Pulses
Authors: Marcy H. O. , Rosker M. J. , Chang Tallis Y. , Khoury J. , Hansen K. , Whetten R.L.
Published: February 2023

The availability of gram-scale quantities of fullerenes allows for the study the of the physical properties of these unique molecules. The large number of highly polarizable electrons associated with fullerene molecules make them potentially attractive as nonlinear optical materials. Structural studies indicate that fullerenes are bound together in the solid state by relatively weak van der Waals forces. An enhancement of the nonlinear optical response for excitation near the band edge, similar to that observed for semiconductor clusters in passive glass matrices, may occur due to the relative isolation of the individual fullerene molecules. Recent reports1–3 indicate that C60 has a relatively large third-order nonlinear optical response at wavelengths far from the band edge -- on the order of that observed for many highly conjugated organic polymers.
Fanning and Photorefractive Self-Pumped Four-Wave Mixing Geometries
Authors: Zozulya A. A.
Published: February 2023

One of the most spectacular achievements in the field of photorefractive nonlinear optics is a practical demonstration of a family of self-pumped fourwave mixing geometries (see e.g. [1,2]) such as the double phase conjugate mirror (DPCM), the passive ring oscillator, the semilinear mirror, the family of mutual conjugators [3-6] that are interpreted on the basis of the system of two coupled DPCMs and the total internal reflection (TIR) conjugator (the "cat" mirror). Despite the fact that operation of these geometries is genetically connected with the effect of asymmetric light-induced scattering (fanning), up to recently it was completely ignored in the theoretical analysis. We present results of recent theoretical and experimental investigations that reveal influence of fanning on the operation of self-pumped FWM geometries and show how fanning in a number of cases determines both their dynamics and final stationary states.
Nonlinear refractive index measurements in thin films of organometallic diacetylene polymer
Authors: Pender William A. , Blau Werner J. , Banim Fiachra , Cardin Christine J.
Published: February 2023

Organic materials with third-order nonlinearities have been widely studied [1]. These materials have potential in all-optical switching technology, using the large and ultrafast nonlinearities in conjugated systems such as polydiacetylenes [1]. We present here experimental results of nonlinear refractive index measeurements from a poly (trans-bis(tri-n-octylphosphine)nickel-diyne-l,4-diyl-butadiyneyl], (Ni:PDA), film spin-coated on a quartz substrate. This polymer is a metal-substituted polydiacetylene (fig2). We also investigate the secondary properties, such as linear absorption and film fabrication.
The Nonlinear Optical Response of Substituted Phthalocyanines and Porphyrins
Authors: Lindle J.R. , Flom Steven R. , Shirk James S. , Bartoli F.J. , Gust D. , Moore T.A. , Moore A.L. , Liddell P.A.
Published: February 2023

The cubic polarizabilities, 〈γ〉, of over thirty substituted phthalocyanines have been previously measured at 1064 nm and/or at 597 nm. 〈γ〉 depends dramatically on the molecular structure and central metal atom.1,2In this paper we report the concentration dependence of the temporal response of χ(3)xxxxand χ(3)xyyxof metal free tetrakis(cumylphenoxy)phthalocyanine (H2Pc(CP)4). Further, the nonlinear optical (NLO) response of several porphyrins, including one substituted with a long chain, carotenoid polyene are reported. For each of these materials the time and polarization dependences observed in degenerate four-wave mixing (DFWM) experiments show that optical pumping contributions enhance the NLO response.
Effect of Chiral Agents on the Optical Fréedeericksz Transition in a Homeotropically Aligned Nematic Film
Authors: Abbate Giancarlo , Ferraiuolo Alessandro , Maddalena Pasqualino , Marrucci Lorenzo , Santamato Enrico
Published: February 2023

Mixtures of nematic liquid crystals (NLC) and cholesteric liquid crystals (CLC) have been widely studied in recent years mainly because of their practical interest in the realization of liquid crystal displays, e.g. twisted or supertwisted cells. Since the 70's it was well established that very small amounts of chiral agents, like CLC, can induce an helical structure on the equilibriun configuration of an NLC cell, modifying its response to external fields.1
Nonlinear optical parameters for InSb at 10.6μm using microsecond pulses
Authors: Smith A.E. , McDuff R.G. , Heckenberg N.R. , Li Chun-fei
Published: February 2023

A semiconductor material which has been widely studied for its optical properties is Indium Antimonide. It shows a usable optical nonlinearity at room temperature in the 9-11 μm wavelength range of the CO2 laser which is of importance in many applications.
Vector Versus Scalar Theory of the Double Phase Conjugate Mirror
Authors: Shaw Kenneth D.
Published: February 2023

The operation of the double phase conjugate mirror (DPCM) has in the past been described theoretically [1] through the use of one-dimensional scalar coupled wave theory [2], This 1-d scalar theory predicts that the DPCM works as an oscillator, with the phase conjugate beams building up from zero at the crystal boundaries (as a function the longitudinal spatial coordinate) when the coupling strength is above some threshold value. In the laboratory, the DPCM does indeed appear to have this property, since its operation is observed to depend critically on the angles of the pump beams inside the crystal with respect to each other and to the crystal’s optic axis, parameters upon which the coupling strength depends. The phase conjugate beams appear to “turn on” suddenly to full intensity as the orientation of the pump beams within the crystal is changed slightly.
Two Picosecond, Narrow-band, Tunable, Optical Parametric Systems Using BBO and LBO
Authors: Zhang J. Y. , Zhou H. T. , Huang J. Y. , Shen Y. R. , Chen C.
Published: February 2023

We report the operation of two picosecond, narrow-band, broadly tunable optical parametric systems using BBO and LBO. The tuning range can be extended from mid-IR to UV with sum and difference frequency generation.
Phase-Matched Second-Harmonic Generation in Waveguides of Polymeric Langmuir-Blodgett Films
Authors: Clays Koen , Penner Thomas L. , Armstrong Nancy J. , Robello Douglas R.
Published: February 2023

Langmuir-Blodgett (LB) films have been fabricated from a preformed acrylate amphiphilic copolymer with nonlinear optical (NLO) active chromophores covalently attached to the polymer backbone. By alternate deposition of this NLO active polymer with a NLO passive amphiphilic polymer, high quality multilayer films have been obtained with sufficient thickness to allow waveguiding in the LB films. The observed optical attenuation is between 1 and 3 dB/cm. The linear and nonlinear optical characteristics of these films have been determined, both in transmission (or reflection) and in waveguide format. The high degree of chromophore order observed in these LB films makes this type of supramolecular structure attractive for NLO applications. Based on the observed parameters (dispersion of the refractive indices, birefringence, absorption, tilt angle of the chromophore, hyperpolarizability), the guided-mode-to-substrate-radiation-mode Cerenkov phase-matching scheme was used for efficient second-harmonic generation.
Fluence Dependent Dynamics Observed in the Resonant Third-Order Optical Response of C60 and C70 Films
Authors: Flom Steven R. , Lindle J.R. , Pong R.G.S. , Bartoli F.J. , Kafafi Z.H.
Published: February 2023

The fullerenes, C60 and C70, are molecules whose properties have been receiving increasing attention. Their high degree of symmetry and their three dimensional π—electron systems make them intriguing candidates for their potential nonlinear optical (NLO) properties. In order to investigate the resonant third—order optical response we have performed time resolved degenerate four—wave mixing (DFWM) experiments on films of pure C60 and pure C70 at 597 and 675 nm using an amplified ps laser system. The films were made by vapor deposition and characterized by FTIR and UV—Visible absorption spectroscopies.
Controlling Chaos in Nonlinear Optical System
Authors: Dai Jian-Hua , Tang Hui , Zhang Hong-Jun
Published: February 2023

Recently, the control of chaos has generated extensive interest and great progress has been made. In general, there are two methods of control, with and without feedback. Ott et al [1] demonstrated that a chaotic attractor typically has embedded with it an infinite number of unstable periodic orbits. By making small time-dependent perturbations of a system parameter, one can convert a chaotic attractor to periodic motion. The nonfeedback control method proposed by Hubler and Luscher [2]. In this report, we present a model of a piecewise function map for controlling chaos in a nonlinear hybrid optical bistable system.
Two-Photon Precision Spectroscopy of the 1S-2S Transition of Atomic Hydrogen
Authors: Hänsch T. W. , Schmidt-Kaler F. , Weitz M. , Leibfried D. , Zimmermann C. , Ricci L. , Wynands R. , Andreae T. , König W.
Published: February 2023

Hydrogen, the simplest of the stable atoms, provides unique opportunities for critical confrontations of spectroscopic experiment and quantum electrodynamic theory. Recent advances in the generation, stabilization, and measurement of optical frequencies are extending radiofrequency resolution and accuracy into the ultraviolet spectral region. Precise measurements and comparisons of the optical frequencies of sharp hydrogen two-photon transitions are yielding new values of fundamental constants, and they are permitting stringent new tests of basic physics laws.
Nonlinear Optical Vortices
Authors: Swartzlander G. A. , Law C. T.
Published: February 2023

Dark soliton stripes (DSS’s) and grids were recently discovered in the cross-section of a laser beam [1] which propagates through a self-defocusing medium. Now we find that a dark soliton stripe can spawn optical vortex pairs of opposite topological charge when subjected to transverse modulations whose period exceeds the soliton size. We have also observed vortices even when solitons are not allowed. This phenomenon can be described by the nonlinear Schrödinger equation (NLS), which also describes vortices in superfluids. To our knowledge, these are the first observations of stationary vortices in a single pass nonlinear optical system.
Optical turbulence in wide gain section lasers: An analogy with large aspect ratio fluids.
Authors: Jakobsen P. K. , Wenden S. G. , Moloney J. V. , Newell A. C.
Published: February 2023

The close synergism between experiment and theory for Rayleigh-Benard fluid convection has led to the development of sophisticated theoretical models which accurately predict the onset of widely diverse pattern forming turbulent convection. Close to threshold a multiple scales weakly nonlinear analysis yields a universal class of amplitude equations which accurately predict the formation of roll, hexagon, defect patterns and various instabilities of the underlying roll solutions. An elegant study by Busse of the nonlinear regime established that turbulent patterns and stable rolls could coexist beyond the first instability threshold.
Interaction of High-Intensity, Ultrashort-Pulse Lasers with Solids and Gases
Authors: Falcone Roger
Published: February 2023

Laser light pulses with ultrahigh intensity (up to 1018 Watts / cm2) and ultrashort pulse duration (down to 100 femtoseconds) were focused on gaseous and solid samples. In gases, the result is highly ionized material with relatively cold electrons, along with the emission of coherent harmonics of the fundamental laser wavelength, x-rays from electron-ion recombination, and far infrared radiation from accelerated electrons. In solids, the result is highly ionized material with hot electrons, with emission of short bursts of intense x-rays.
Dynamic Three-Dimensional Propagation of Light Pulses
Authors: Luther G.G. , Moloney J.V. , Hart D.E. , Wright E.M.
Published: February 2023

Recent work has shown that the fully spatio-temporal propagation of a light wave envelope in a cubically nonlinear medium displays, in addition to the usual transverse structures, longitudinal dynamics which play an essential role in the evolution of the wave [1, 2, 3]. A recent computational effort has illustrated that the presence of dispersion can inhibit collapse due to two dimensional self focusing in normally dispersive media causing structure in the propagation direction as well as the transverse direction [3]. Analysis of three dimensional propagation of light waves in anomalously dispersive media [4, 5] reveals a set of symmetric solutions which would exist in the intermediate state between collapse and dispersal.
Efficient High Power Stokes and Anti-Stokes Raman Frequency Generation via Polarization Tuning Enhancement
Authors: Hermann Mark R. , Norton Mary A.
Published: February 2023

A method for producing high-power broad-band coherent light via rotational Raman Stokes and anti-Stokes frequency generation in H2 is presented. A variety of potential applications include atmospheric imaging, ranging, and remote sensing. Another important potential application is producing a high-energy broad-band laser source to reduce plasma instabilities in inertial confinement fusion. The process presented here is divided into three steps. The polarization of the fields is tuned at each stage to control and optimize rotational Raman conversion. The system consists of a focused Stokes seed oscillator, collimated Stokes amplifier and a parametric mixer. A small Stokes seed is generated in a focused oscillator. A circularly polarized pump field is used here to supress parametric four-wave coupling, which insures good spatial beam quality and efficient energy conversion to first Stokes1. The circularly polarized Stokes seed is then combined with an opposite circularly polarized pump field in a collimated Raman amplifier. Again circular polarization suppresses competing parametric conversion to higher order Stokes or anti-Stokes fields. In the third stage a linearly polarized pump is combined with the amplified Stokes field, which is linearly polarized parallel to the pump and has comparable energy, in a collimated parametric mixer. Parallel linear polarization is used to maximize the parametric conversion in this final stage. Since collimated Raman cells are employed in the last two stages, this system in principle is scalable to large laser systems. This is a distinct advantage over conventional focused Raman systems 2,3, which by nature are limited in operation to small energy regimes by gas breakdown.
The role of radiation trapping in nonlinear optical processes in atomic vapors
Authors: Lange W. , Ankerhold G. , Schiffer M. , Mutschall D. , Scholz T.
Published: February 2023

In this work we report on experimental and theoretical investigations of novel features of radiation transport in gases and discuss their significance for nonlinear optical processes in atomic media. Radiation diffusion is found to alter many nonlinear processes based on intensity dependent changes of level populations, to influence the timescales involved in experiments and to have drastic effects on the spatial distribution of extrinsic nonlinearities.
A Numerical Exploration of Optical Soliton Reflection and Transmission At a Nonlinear/Dispersive Fiber Boundary
Authors: Ziv Ofer , Chatterjee Monish R.
Published: February 2023

This paper describes a computerized approach to the problem of optical soliton reflection and/or transmission at an optical guide boundary. Even though a considerable amount of work has been concentrated on the process of generating and examining soliton pulses in optical fibers [1-4], some attention needs to be focused on the actual stability of these pulses vis-a-vis such physically realistic effects as geometrical distortions in the fiber, including bending and torsion, and the associated radiation and mode-conversion phenomena. A robust soliton communication system must take into account the possibility of solitons breaking up at boundaries and discontinuities, or perhaps "hopping" between lower and higher orders.
Study on the Oxidation of Chemical Compound at an Activated Polycrystalline Silver Surface Probed by SHG Technique
Authors: Zheng Jia-Biao , Liu Yang-Hua , Wang Wen-Cheng , Zhang Zhi-Ming
Published: February 2023

The oxidation of ethanol is an important process in chemical industry where fine particles of pure silver activated by adsorbed oxygen are used as the catalyst. However two different kinds of mechanism were proposed to explain this oxidation reaction but under controversies. One is the Langmuir-Hinshewood mechanism which claimed that the ethanol molecules were firstly adsorbed on the silver surface and then reacted with the adsorbed oxygen, the other, Eley-Rideal mechanism, claimed an one-step process is active that is the ethanol molecules in gaseous state reacted directly with the adsorbed oxygen when they collided on the silver surface. Hence it is suggested to have a new technique which might be able to discriminate these two mechanisms and here, we will report our recent study on this oxidation reaction by probing with the optical technique of second harmonic generation (SHG).
Technique for characterization of laser-induced dielectric gratings: Application to non-photorefractive cubic KTaO3:Cu
Authors: Xia Ping , Partanen J. P. , Hellwarth R. W.
Published: February 2023

Two constant overlapping monochromatic laser beams can interfere in any homogeneous medium to produce a spatially sinusoidal variation

Δ

ε
⇀

⇀

Ae in the complex dielectric tensor (i.e. an "optical grating").1 In most experiments in insulators to date, the optical grating arose either from the photorefractive effect or from optically excited impurities such as Nd3+ in YAG. In general

Δ

ε
⇀

⇀

may be written as a superposition of complex sinusoidal variations that are in and out of phase with the optical beam interference pattern. In this paper we describe a simple and efficient technique for measuring both the spatially in-phase and out-of-phase components of at least one complex tensor component of

Δ

ε
⇀

⇀

. In those rare cases where desired information resides in the other tensor components, our method can be extended to measure them. We illustrate our technique by measuring an optical grating produced by 633 nm beams in a cubic KTaO3:Cu crystal which is not photorefractive. Nevertheless, the grating is comparable in magnitude to photorefractive gratings. Also the grating is quite visible to our technique, even though there is almost no steady-state energy exchange between the beams. Our method is an extension of one used by Zha, et al.2 to monitor photorefractive gratings.
Optical Phase Conjugation As Zakharov-Shabat Problem
Authors: Ghosh Roy D. N. , Rao D. V. G.
Published: February 2023

The generation of an optically phase conjugated signal in four-wave-mixing (FWM) is usually interpreted1–2 as a coherent addition of diffracted waves from the grating structures formed in the nonlinear optical medium by the pump beams. In this paper, optical phase conjugation (OPC) is analyzed from a different point of view, namely, that of potential scattering. The optical medium acts as a "potential” which scatters the incoming probe wave nonlinearly into the conjugate signal, the potential being generated by the counterpropagating pump waves. It is shown that in this picture, transient OPC is described by the Zakharov-Shabat eigenvalue problem3 (ZSP) which is the linear scattering problem for a class of evolution equations such as the nonlinear Schrodinger equation. The methodology of the inverse scattering transform3-4 (1ST) can thus be used to analyze the problem. Many of the well established results of OPC are rederived in this paper using this approach along with some new ones. Moreover, an inverse scattering problem is posed regarding the time evolution of the potential which directly reflects the molecular dynamics involved.
Origin of ultrafast dynamics in time-resolved impulsive stimulated Raman scattering (ISRS) from molecules in liquids.
Authors: Hayashi M. , Fujimura Y.
Published: February 2023

1. One of the features in ultrashort time-resolved nonlinear coherent scattering spectroscopy is creation of a transient intermolecular coherence in molecular liquids. 1,2 For example, teraheltz quantum beats appear in time-resolved coherent anti-Stokes Raman scattering (CARS) and time-resolved impulsive stimulated Raman scattering (ISRS) profiles as a result of the creation of the intermolecular vibrational coherence. Such time-resolved profiles provide us information on the mechanism of the intermolecular dynamics. Recently, Nelson group has reported the time-resolved ISRS profile of dibromomethane liquid.2 The most distinctive feature is the appearance of 5.2 teraheltz quantum beat with two apparent decay components. The quantum beat is associated with the creation of intermolecular, vibrational coherence between Raman transitions of 173 cm-1 bending mode of dibromomethane molecules at different sites. The time-development behavior was not clarified from the microscopic point of view.
Spatial Solitons in a Self-Focusing Semiconductor Gain Medium
Authors: Khitrova G. , Gibbs H.M. , Kawamura Y. , Iwamura H. , Ikegami T. , Sipe J.E. , Ming L.
Published: February 2023

The pulse broadening by group velocity dispersion can be balanced by the narrowing effect of self-phase modulation to form temporal solitons.1 The identical nonlinear Schrödinger equation describes the one-transverse-dimension balancing of diffraction and Kerr-medium nonlinear refraction. Some evidence for spatial solitons has been published for planar waveguides of CS2 and glass, both in Kerr (n2) media.2,3 Here we report soliton formation in a semiconductor gain medium which is amplifying rather than lossy, is accumulative rather than instantaneous, and is near resonance instead of far from resonance.
Photorefractive Interference Filters: Theory and Application
Authors: Johansen P.M. , Petersen P.M.
Published: February 2023

Interference filters generated in fotorefractive materials have only been investigated very briefly in the literature1. In the present analysis the configuration for the interference filter is shown in Fig. 1. Two coherent laserbeams E1and E2are incident on a photorefractive barium titanate (BaTiO3) crystal. Due to the photorefractive effect2these two incident beams induce a periodic change, with periodicity Λ, in the refractive index of the crystal. A third beam, E3, incident along the x-direction experiences varying layers of high and low index of refraction. The situation experienced by E3is analogous to that experienced in a multilayer dielectric mirror3with alternating quaterwave layers of high and low index.
Real-Time All-Optical Serial-to-Parallel Conversion of Sub-Tbits/s Signals
Authors: Ema K. , Kuwata-Gonokami M. , Urakami T. , Nakamura T. , Aoshima S.
Published: February 2023

Rapid development of the technologies for generation and shaping of ultrashort optical pulses allow us to produce ultra-high-speed signals over Tbits/s.1-4) We can construct high capacity Tbits/s data processing system by combing this ultrashort optical pulse technology and electronic device technology. For this purpose, we need all optical serial-to-parallel conversion to to transfer the high-bit-rate optical pulses to the slower electronic devices without loosing the data capacity. Recently we have demonstrated a serial-to-parallel conversion of sub-Tbits/s signals using giant excitonic third-order nonlinearity of a ZnSe film.5) The conversion is the transformation from a temporal shape (serial signals) to a spatial pattern (parallel signals) using a nonlinear mixing with a read-out pulse. In the previous report we showed the switching of time-integrated parallel signals responding to the on-off switching of a read-out pulse. In this paper, we report the time-resolved measurement of the parallel signals to confirm the capability of serial-to-parallel conversion at picosecond order. The conversion using second-order nonlinearity is also demonstrated.
Observation of Dynamic Frequency Chirp in Bistable Semiconductor Laser Amplifiers
Authors: Pan Zeqi , Dagenais Mario
Published: February 2023

Dispersive optical bistability in a Fabry-Perot, a distributed feedback (DFB), or a distributed Bragg reflector (DBR), semiconductor laser amplifier has recently attracted much attention, because of its potential in the operation of highly functional optical devices. While the steady-state operation of bistable diode laser amplifiers are well understood, studies of the dynamic properties have been limited to switching time, critical slowing down and output spiking measurements[1-3]. Little attention has been paid to the dynamic frequency chirp which is associated with the turn-on spike at the onset of light injection. Such frequency chirp exists because in dispersive bistability the Fabry-Perot resonance (or the DBR/DFB transmission peak) sweeps through the injected wavelength as a result of alight induced refractive index change. In this paper, we report on a theoretical analysis and the first experimental observation of this dynamic chirp in a Fabry-Perot type nonlinear semiconductor laser amplifier. It is found that the magnitude of the chirp depends on the input power, which in turn is related to critical slowing down.
Prospects for Fast Access Holographic Memories
Authors: Hong John , McMichael Ian , Ma Jian , Chang Tallis , Christian William , Pletcher David , Khoshnevisan Monte
Published: February 2023

A unique feature of holographic memory is its potential for fast random access if nonmechanical means for page addressing are implemented. It is possible to obtain 10 microsecond latency (equivalent to disk head seek time) by using acoustooptic deflectors to steer the address beam in an angularly multiplexed holographic memory system. When 1-100 GByte storage capacities are considered, however, the nonmechanical addressing constraint poses challenging design problems. In this paper, we describe fast access holographic memory architectures and discuss the critical design issues. We also describe recent Rockwell efforts to develop a fast access holographic memory system.
Shift Multiplexed Holographic 3-D Disk System
Authors: Pu Allen , Psaltis Demetri
Published: February 2023

We have demonstrated for the first time a fully functional holographic disk system using shift multiplexing. The architecture of our system is similar to the compact disc, but with higher storage density and data transfer rate. Figure 1 shows the experimental setup. An amplitude data mask containing 590,000 random bits (pixels) is imaged to the detector plane by a pair of Nikon F/1.4 50mm camera lenses. A 120mm glass substrate coated with a holographic recording medium (DuPont's HRF-150 100 micron thick photopolymer) is placed slightly after the Fourier plane of the camera lenses. The photopolymer disk is rotated by a microstepping motor capable of 125,000 steps per revolution. A F/1.4 CCD camera lens is used to create the spherical reference beam necessary for shift multiplexing [1]. The stored data is retrieved by a CCD camera placed at the detector plane.
Exciton Polariton Boser
Authors: Yamamoto Y. , Pau S. , Cao H. , Björk G.
Published: February 2023

Wannier excitons in a GaAs quantum well planar microcavity strongly couple with a single-mode photon field and form "microcavity exciton-polaritons". This quasi-particle has a bosomic character when the inter-particle scattering is negligible. Compared to GaAs bare excitons, exciton-polaritons have much lighter mass (by four orders of magnitude) and thus the thermal de Broglie wavelength of GaAs exciton-polaritons is 100 times longer than that of GaAs bare excitons at the same temperature. Therefore, the quantum statistical effect should emerge at a relatively low density.
Novel High Nonlinearity Organic Crystals
Authors: Guenter Peter
Published: February 2023

We will present the most recent results on the growth and characterization of novel high quality molecular crystals for nonlinear optics. These crystals are based on ionic or hydrogen bonding of new and known chromophores with large second-order hyperpolarizabilities. Detailed results of optical, electro-optical and nonlinear-optical properties of high quality and large size DAST crystals, of hydrazone derivatives and new co-crystals will be presented. It will be shown that optimized parallel alignment of chromophores as well as optimum structures for phase-matched frequency mixing have been realized. In addition, we report on the measurement of the highest known phase-matchable nonlinear susceptibility coefficient of 200 pm/v determined recently in our laboratory.
Nonlinear Optical Properties of Azulene
Authors: McDonald J. K. , Christensen C. R. , Inguva Ramarao
Published: February 2023

Azulene is an aromatic hydrocarbon that, in addition to being an isomer of naphthalene, is also isoelectronic with it.
Oscillator Strength, Dephasing and Stark Shift of Free and Three-Dimension Confined Excitons
Authors: Dagenais Mario
Published: February 2023

The concept of giant oscillator strength for both free and bound excitons is elucidated. It is shown that, the oscillator strength of these transitions is enhanced over the free exciton oscillator strength per molecule of the crystal by the ratio of the volume of the system divided by the volume of the crystal unit cell. An expression for the free exciton oscillator strength is obtained that can be used to describe the AC Stark shift of an excitonic resonance and also its saturation behavior.
Nonlinear Ground State Fluctuations (Zero Point Motion) as the Source of χ(3) in Polyacetylene
Authors: Sinclair M. , Moses D. , McBranch D. , Heeger A. J. , Yu J. , Su W.P.
Published: February 2023

For a deeper understanding of the nonlinear optical response of conjugated polymers, the connection between the nonresonant response to pumping well below the absorption edge and the resonant response to pumping into the absorption band must be developed. For trans -(CH)X, resonant pumping causes photogeneration of charged solitons; the resulting shifts in oscillator strength lead to relatively large changes in the optical constants. We generalize to the nonresonant regime where the nonlinear response arises from virtual soliton-antisoliton (SS) pairs and is enabled by nonlinear ground state fluctuations, or "instantons".
Perspectives on The Quantum Electrodynamics of Detection
Authors: Gustafson T.K.
Published: February 2023

Detection will be discussed from a broad perspective with particular emphasis on those aspects and questions which are of concern when the quantized nature of the radiation field is important.
Dispersion compensation by prechirp technique in multigigabit optical amplifier repeater systems
Authors: Henmi N. , Saitoh T. , Fujita S. , Yamaguchi M. , Asano H. , Mito I. , Shikada M.
Published: February 2023

Non-regenerated repeater systems [3-6] with Er3+-doped fiber amplifiers have a great potential in the near future application by reason of high gain, low noise [1,2] and bit rate free characteristics. Lately, over 2000 km and 20 stages multi-Gb/s repeater system experiments are demonstrated [5]. It is predicted that the transmission length can be expanded nearly 10000 km, which corresponds to the transoceanic system.
Characteristics of Single-Carrier Fiber-Optic Transmission Systems using Optical Amplifiers
Authors: Yamamoto S. , Taga H. , Yoshida Y. , Wakabayashi H.
Published: February 2023

The capability of a very long-distance transmission using erbium-doped fiber amplifiers (EDFAs) has been demonstrated by using a circulating loop.[1],[2] In a single-carrier long-distance fiber transmission system, the signal wavelength will usually be tuned to the zero dispersion wavelength of the fiber to avoid the pulse waveform distortion due to chromatic dispersion. It has also been reported that when the signal wavelength is located exactly at the zero dispersion wavelength, the mixing of the signal with the spontaneous emission from the optical amplifiers will produce four-wave mixing sidebands.[3] However, in the practical systems, the fiber chromatic dispersion varies along the long transmission path and may alleviate the effect of the four-wave mixing. [3]
Porous Halide Antireflective Coatings for Adverse Environments*
Authors: Thomas Ian M.
Published: February 2023

Many metal fluorides are stable in adverse environments and some are used as coatings for optical components. In general, these materials have low refractive indices and are therefore of use as the low index component in multilayer AR or HR coatings or, in some cases, notably MgF2, as the single component in simple 1/4 wave AR coatings. These coatings are normally prepared by evaporation or sputtering and as such are substantially dense and therefore of an index close to that of the bulk fluoride material. This is quite satisfactory for multi-layer application but is inefficient in 1/4 wave AR coatings on typical substrates of index about 1.5 because the index is too high.
Gamma Radiation-Induced Absorptions In Calcium Fluoride
Authors: King C. W. , Nestor O. H.
Published: February 2023

The characteristics of calcium fluoride under adverse conditions have received increasing attention in the last several years. Many workshops and symposia have focused on laser induced damage in calcium fluoride and other materials when used as laser windows.
Effect of Surface Pitting in Transparent Domes on Scattered Light
Authors: Ricks Douglas W.
Published: February 2023

A dome which covers an optical instrument is designed to protect the optical instrument from pitting caused by the impact of dust, rain or hail. When flown on the wing or nose of high speed aircraft the erosion can be severe. This adverse environment will degrade the optical performance of the instrument by decreasing transmittance and by increasing the amount of light scattered by the dome.
Intracavity gain detection: example I2, Br2
Authors: Truesdell Keith A , Keller Richard A.
Published: February 2023

It is well known that a broadband dye laser is extremely sensitive to small absorption losses within the laser cavity and this phenomenon forms the basis for intracavity absorption spectroscopy. In a similar fashion, introduction of small optical gains into the laser cavity results in the laser locking onto wavelengths corresponding to these small gains. This internal gain injection locking leads to a method for (1) sensitive detection of small optical gains, and (2) specific state preparation for spectroscopic or chemical dynamic studies. A particularly attractive feature of this technique is that it is not necessary to know the wavelength where gain occurs before the measurement because the dye laser automatically finds the correct wavelength. Optical pumping with radiation from an external Ar+ laser was used to create population inversions between vibronic levels in molecular I2 and Br2 samples placed inside the cavity of a cw dye laser. We are able to detect optical gains as small as 2 × 10−5 on transitions between states in these molecules. By tuning the Lyot filter we are able to selectively populate specific, high-lying vibrational levels of the ground electronic state of both I2 and Br2. The internal injection resulted in the first reported cw lasing of Br2 in the visible spectral region.
Three-photon optical excitation of a slightly relativistic single electron
Authors: Kaplan A. E.
Published: February 2023

We showed earlier1 that a single electron in a magnetic field can exhibit hysteretic cyclotron resonance when the frequency of driving EM field is close to the cyclotron frequency (usually in the microwave range). This effect is based on a slightly relativistic mass effect of the electron; recently it has been observed experimentally.2 Here we show that based on the same small relativistic dependence, yet another nonlinear optical effect can be predicted: large excitation of microwave (or rf) cyclotron motion of a single electron in the Penning trap by two optical waves, when their respective frequencies ω1 and ω2 differ approximately by the double cyclotron frequency ω0, i.e., |ω1 − ω2| ≃ 2ω0. The critical amplitudes of the optical fields required to attain such an excitation are very low, e.g., E1,2 ≃ 10−2V/cm if λ1,2 ≃ 10 μm and λ0 ≃ 2 mm. From the quantum electronics standpoint this effect may be regarded either as a three-photon process (ω0 = |ω1 − ω2| −ω0) of as a higher-order stimulated Raman scattering. Since the conduction electrons in some semiconductors may also exhibit pseudo-relativistic nonlinear cyclotron resonance,3 the analogous three-photon optical excitation may also be expected in semiconductors.
Experimental test of the single-Gaussian mode theory of optical bistability
Authors: Orozco L. A. , Rosenberger A. T. , Kimble H. J.
Published: February 2023

In nonlinear optical interactions, one expects the transverse spatial intensity dependence to be modified. Nonlinear interactions within an optical resonator, in the absence of a mode-selective element such as an aperture, will thus in general couple the energy into various transverse modes of the resonator. One attractive analytical model incorporating transverse effects into optical bistability assumes, in spite of the observations above, that the transverse intensity profile remains a single-Gaussian (TEM00) mode. This model seems to be supported by experimental results for bistability with two-level sodium atoms in a confocal ring resonator. To test the generality of the single-Gaussian mode model, we have performed bistability experiments with two-level atoms in standing-wave resonators. Two resonators, differing only in length, were used. The confocal resonator is transverse-mode-degenerate and will support a combination of modes, as would the ring; the slightly longer resonator will allow only a single-transverse mode to be excited. Preliminary results indicate that there may be a difference in the two cases; although the behavior near the critical onset of bistability seems to be the same in the two cases, there seems to be a difference in the evolution of hysteresis with increasing cooperativity parameter. Further results, including a quantitative comparison with the single-Gaussian mode theory for standing-wave resonators, are presented.
Wavelength compensations for holographic scanners
Authors: Ih Charles S. , Zhuang B. H. , Xiang L. Q.
Published: February 2023

Hologram reconstruction is very sensitive to the wavelength. When the reconstruction wavelength is changed, there is an angular and a focal-length shift resulting in both a lateral shift and a longitudinal shift of the reconstructed image. There is also associated wave front distortion. All these have adverse effects on the holographic scanners if semiconductor lasers are used as the light source. We have investigated these problems and found that by using an additional grating or hologram, these adverse effects can be sufficiently compensated so that the scanners can be used for practical applications. For example, our studies have shown that the angular shift can be reduced by 100 times while keeping the wave front distortion within an acceptable range. We also found that the scan line straightness worsens by as much as 34%. However, these may be still within the acceptable range for less critical applications. The trade-offs between different parameters for different applications are discussed. Our preliminary results indicate that a practical holographic scanner system employing GaAlAs (or GaAs) lasers with good efficiency and good wavelength shift tolerance can be designed and built.