bluuebunny/crossref_metadata_2025 huggingface dataset:
Competitiveness and investment attractiveness of regions
Authors: Popadyuk Nikita , Rozhdestvenskaya Irina , Kabalinskiy Aleksey , Sokolov Nikolay
Published: February 2023

In the context of the reformatting of the new world order, the question of the competitiveness of countries and regions also arises in a new way. At the same time, a set of factors and conditions that determine the competitiveness of regions and its key link, such as their investment attractiveness, are beginning to be perceived in a special way. And the point here is not only in the specific components of the investment potential of competing regions, but also in such combinations of them as become the subject of the art of management. Moreover, being an intangible asset in its economic content, regional competitiveness is able to actualize those aspects, for example, the economic and geographical location of the region, which have not been considered as an asset for a long time, although they have enormous potential.
Meets the requirements of the federal state educational standards of higher education of the latest generation.
It is intended for master's degree students in the field of preparation 38.04.04 "State and municipal administration", as well as for undergraduate students in the same direction. In addition, it will be interesting for teachers who read disciplines on regional economics and management of competitiveness and investment attractiveness of regions.
Penitentiary criminology
Authors: Rastoropov Sergey , Pikin Ivan , Gorshkova Natal'ya , Ponkratov Vasiliy , Prohorova Marina , Smirnov Leonid
Published: February 2023

The textbook was prepared on the basis of the work program of the discipline "Penitentiary criminology". It contains theoretical material intended for preparation for lectures and seminar-type classes. It includes control questions and assignments, as well as a bibliographic list. The textbook is aimed at mastering the key provisions and issues of penitentiary criminology by students, as well as at forming practical skills and skills necessary for the organization of effective activities of correctional institutions, including the prevention of penitentiary crimes.
Meets the requirements of the federal state educational standards of higher education of the latest generation.
For cadets, trainees, students studying in the specialty 40.05.02 "Law enforcement", as well as adjuncts, graduate students, teachers and researchers of law schools, including the system of the Federal Penitentiary Service. It can be useful for practitioners of the penal enforcement system.
IT risk management
Authors: Scherbak Aleksey , Andreev Vladimir , Zubov Afanasiy
Published: February 2023

The monograph examines the features of risk management in the field of information technology, describes the methodology for building the organizational structure of risk management, analyzes the sequence of steps to establish risk control, pays great attention to the methods and tools of risk management in IT. It provides information about strategic and tactical risks, as well as project risks, and examines the nuances of launching and controlling risk management in IT.
It is intended for a wide range of specialists whose activities are associated with risks in the field of IT, for teachers, as well as for students of enlarged groups of training areas and specialties "Computer Science and Computer Engineering", "Information Security" and "Electronics, radio engineering and communication systems".
The life of modern generations: socio-psychological trends
Authors: Pischik Vlada , Chernousova Tat'yana , Postnikova Margarita , Miklyaeva Anastasiya , Sivrikova Nadezhda , Abakumova Irina , Akopov Garnik
Published: February 2023

The monograph includes studies of the last decades by a group of scientists engaged in solving problems of theoretical and methodological study of the problem of psychological manifestations of modern generations. The authors reflected the versatility of definitions of the concept of "generation" and revealed the multidimensional phenomenon of generations. The author's approach to the succession of generations deserves attention, which opens up prospects in the study of intergenerational relations. A level model of value-semantic mediation of intergenerational relations is presented, which allows a comprehensive look at the manifestations of generations. Reviews of generational studies are presented and empirical cross-sections are presented in the value-semantic perspective of the formation of generations. The problem of perception of generations by each other in age and gender aspects is considered in a special way. Attention is paid to the problems of spreading the belief in conspiracies in the modern youth environment and the harmful consequences of this. The empirical model of the conspirativist mentality is the beginning of research in this regard.
It is addressed to philosophers, cultural scientists, sociologists, psychologists of various schools and anyone interested in new and recurring trends in human development in the world.
The implementation of the educational process in universities: the practice of dispute resolution. Comment
Authors: Prokof'ev Stanislav , Ruchkina Gul'nara , Gorohova Svetlana , Ivanova Elena , Moiseev Andrey , Muradyan Alena , Pushkin Aleksandr , Kashirin Sergey
Published: February 2023

The textbook includes a legal analysis of a wide range of legal conflicts related to the implementation of the educational process by universities, and also contains a detailed overview of individual court cases arranged by thematic categories. The publication examines the most common court disputes, provides arguments of the parties and the courts themselves, which are important when making a legally significant court decision.
Meets the requirements of the federal state educational standards of higher education of the latest generation.
It can be in demand in the educational process during the preparation of bachelors, masters and postgraduates in the field of jurisprudence. In addition, the textbook is able to interest rectors and legal services of universities, practicing lawyers and lawyers, as well as all other persons involved in the educational process in higher education.
Colombian Liberalization and Integration into World Trade Markets: Much Ado about Nothing
Authors: Cepeda-López Fredy , Gamboa-Estrada Fredy , León-Rincón Carlos , Rincón-Castro Hernán
Published: February 2023

The objective of this article is to study the evolution of Colombian liberalization and integration into world trade from 1996 to 2018. We achieved our objective by measuring Colombia’s importance in the world trade network through the employment of several types of network centrality metrics and the examination of their dynamics against a set of regional peers. We were able to conclude that Colombia’s centrality in the world trade network did not improve, whereas that of some of her regional peers did manifestly. Results highlighted the perils of analyzing a country’s trade dynamics in isolation and emphasized the usefulness of examining the world trade network.
Mental disorders in people with keratoconus
Authors: Florek Szymon , Pudlo Robert , Gościniewicz Piotr , Mrukwa-Kominek Ewa
Published: February 2023

Introduction: There are many reports on the association of various psychiatric disorders with visual impairment. The association of dry eye syndrome with depressive disorders has been particularly well documented. In the context of keratoconus patients group, data on similar relationships are inconclusive. Attempts have also been made to assess the personality of patients
suffering from keratoconus, and the first study in this area was produced as early as 1976.
Material and methods: For the literature review, full-text medical databases, such as PubMed and Embase, were searched for articles on the association of keratoconus with depressive-anxiety disorder and personality disorder. Articles published within the last 30 years were considered.
Results: The personality of patients with keratoconus has been a research issue for many years, but research to date has not clearly defined what personality traits characterise this particular group of patients. Research into the relationship between keratoconus and depressive-anxiety disorders has only recently been conducted, and the results - although inconclusive - suggest a co-occurrence of depressive symptoms with keratoconus. A different and interesting field for further research is the association of keratoconus with schizophrenia, as these diseases may have a common background.
Conclusions: A review of the literature does not identify a 'keratoconus personality', but there are reports of specific functioning in patients with keratoconus. There are isolated reports in the literature regarding the co-occurrence of keratoconus and depressive-anxiety disorder.
Keywords: depression, personality, anxiety, psychiatric disorders, keratoconus
Beyond Biofuels
Authors: Willis Paul
Published: February 2023

Launch system developers are testing biofuels to ensure growth in orbital businesses is environmentally sustainable
Continuous material reflectance map for deep photometric stereo
Authors: Prouteau Nicolas , Joubert Clément , Bringier Benjamin , Khoudeir Majdi
Published: February 2023

Solving calibrated photometric stereo under a sparse set of lights is of great interest for real-world applications. Since neural networks show advantages in dealing with material appearance, this paper proposes a bidirectional reflectance distribution function (BRDF) representation, which is based on reflectance maps for a sparse set of lights and can handle various types of BRDFs. We discuss the optimal way to compute these BRDF-based photometric stereo maps regarding the shape, size, and resolution, and experimentally investigate the contribution of these maps to normal map estimation. The training dataset was analyzed to establish the BRDF data to use between the measured and parametric BRDFs. The proposed method was compared to state-of-the-art photometric stereo algorithms for different datasets from numerical rendering simulations, DiliGenT, and our two acquisition systems. The results show that our representation outperforms the observation maps as BRDF representation for a neural network for various surface appearances on specular and diffuse areas.
High-Quality Femtosecond Fundamental Soliton Compression in Optical Fibers with Varying Dispersion
Authors: Dianov E. M. , Ivanov L. M. , Mamyshev P. V. , Prokhorov A. M.
Published: February 2023

Generation of femtosecond solitons is of great interest for the fundamental research as well as for practical applications.
Time-Resolved Waveguide Modulation of a Conjugated Polymer
Authors: Sinclair M. , McBranch D. , Moses D. , Heeger A.J.
Published: February 2023

Most applications of conjugated polymers in nonlinear optical devices will require knowledge of the intensity-dependent refractive index, defined by where n0 is the linear index, and I is the light intensity. We have developed a technique1 which allows for time-resolved measurements (to distinguish between thermal and electronic nonlinearities) of n2.
Applied Mathematics Perspectives of Nonlinear Guided Wave Optics: Stability, Propagation and Soliton Aspects
Authors: Moloney J. V.
Published: February 2023

Traditionally nonlinear optical waveguide theory has evolved as a natural extension of linear waveguiding concepts. In this picture, low-power guided waves are supported by discontinuities or gradations in material refractive indices and the optical nonlinearity plays a rather passive role, modifying slightly the mode propagation constant. Linear coupled mode analysis, when extended to incorporate nonlinear effects, predicts a variety of novel switching effects such as nonlinear directional coupling or bistable response in feedback geometries. The theoretical observation that at higher incident power, a single interface (planar waveguide) could support novel stationary nonlinear surface (guided) waves, if at least one of the bounding dielectric media displayed a positive nonlinear optical response to the applied electromagnetic field, has led to an explosive growth of the literature on nonlinear waveguides [1]. Parallel studies have employed the beam propagation method (BPM) to study the asymptotic states of self-focused channels incident at oblique angles to a nonlinear interface [2]. More recently the BPM has been used as a computational tool to investigate stability of the above analytically computed stationary nonlinear surface (NSW) or guided (NGW) waves [3].
Polarization Instabilities and All-Optical Switching in Waveguides
Authors: Wabnitz S. , Trillo S.
Published: February 2023

Recent experiments have shown that optical fibers have the capability of generating and transmitting information at THz rates.1 This motivates the demand of future optical communication and computing systems for optical processing devices operating before electronic detection, i.e., in an all-optical fashion. The possibility of controlling the switching of an optical signal by means of another light beam was initially demonstrated with bistable elements, e.g., the nonlinear Fabry-Perot.2 In this case, main limitations to the switching speed arise from the resonator transit time and thermal heating. Pipeline all-optical processing of a data stream is also possible in a traveling wave configuration, for example using a nonlinear directional coupler3 or a Mach-Zehnder interferometer.4 In this case, interaction between controlling and controlled signals occurs through the intensity dependence of the refractive index, and successive pulses may get switched simultaneously while propagating along the device, so that the traveling time no longer sets a limitation to the switching speed. The shortest pulses which can be processed will then be determined by the response time of the nonlinearity, which can be of the order of a few optical cycles for glass fibers, and the combined effect of group-velocity dispersion (GVD), self-phase modulation (SPM) and cross-phase modulation (CPM).
All-Optical Switching in X-Junctions
Authors: Sabini J.P. , Finlayson N. , Seaton C. T. , Stegeman G. I.
Published: February 2023

The potential use of nonlinear waveguide devices for ultrafast signal processing leads to a growing interest in their switching characteristics. Given the two main advantages of guided wave optics over bulk optics for nonlinear interactions, i.e. the high power densities achievable in waveguides at low absolute powers and diffractionless propagation of the light over long interaction lengths, the use of relatively weak nonlinearities becomes possible. Standard integrated optical devices can be operated in an all-optical mode by using materials exhibiting intensity-dependent refractive indices.
Polarization Rotation in Non-Linear Bi-Modal Optical Fibers
Authors: Garth Stephen J. , Pask Colin
Published: February 2023

The current interest in lightwave polarization developement and nonlinear optics has centred on birefringent single-mode fibers [1]. We consider circular core fibers supporting second order modes. In the linear case a natural polarization rotation phenomenon occurs [2] and we describe its development as nonlinear effects become important. We stress from the outset that no birefringence is assumed; polarization rotation is a distinctive waveguide effect due to continuous reflections at a cuurved core-cladding boundary.
Nonlinear Optical Response of an Optical Fibre Loop Mirror Device
Authors: Nayar B K , Doran N J , Forrester D S
Published: February 2023

The advantages of all optical signal processing for high bit rate systems are increasingly being recognised and have stimulated interest in the demonstration of all-optical switching and logic operations. In particular optical fibres have been used to demonstrate optical switching by nonlinear polarisation rotation{1−3}, in the Mach-Zehnder interferometer configuration{4} and through nonlinear coupling{5}. Optical fibres are preferred as they permit ultrafast switching (the intensity dependent index change, n2, originates from nonresonant electronic process), have low loss, and can be used to fabricate all fibre devices. Otsuka{6} has proposed a nonlinear antiresonant ring interferometer for realisation of several optical functional devices. An all optical fibre loop mirror is a guided wave version of this device and has the advantage that it requires no interferometric alignment. Doran et al{7} have theoretically investigated nonlinear properties of this device and in this paper we report first experimental demonstration of the nonlinear response of such a device.
All-optical and electrooptical control of a nonlinear directional coupler with a multiple-quantum-well coupling region
Authors: Cada M. , Keyworth B. P. , Glinski J. M. , Rolland C. , SpringThorpe A. J. , Hill K. O. , Soref R. A.
Published: February 2023

Preliminary experimental results are reported on all-optical and electrooptical control of transfer of light energy in a GaAs-based multiple-quantum-well-coupled planar nonlinear directional coupler. It is believed that this is the first semi-conductor ΔK switch and the first report on results obtained near the exciton-resonance wavelength.
The Physics of Nonlinear Couplers is Revealed by its Normal Modes
Authors: Snyder A. W. , Mitchell D. J.
Published: February 2023

All work on nonlinear couplers gives one the impression that previous knowledge of linear couplers must be completely abandoned. In particular, linear (axially uniform) couplers have normal modes which do not couple whereas the analysis of nonlinear couplers has been via coupled mode theory1,2,3.
Avoidance of Pulse Break-up in All-Optical Switching by Using Femtosecond Square Pulses
Authors: Weiner A.M. , Silberberg Y. , Fouckhardt H. , Leaird D.E. , Saifi M.A. , Andrejco M.J. , Smith P.W.
Published: February 2023

All-optical switching devices may play an important role in future highspeed communications systems. Recently we demonstrated switching of 100-fsec pulses by a dual-core fiber all-optical switch [1]. One problem associated with short pulse operation of the dual-core fiber switch, or any all-optical switch triggered by instantaneous intensity, is pulse break-up: switching can occur within a pulse, so that low and high intensity portions of the same pulse are directed to different output ports [1,2]. Proposals have been made to solve the pulse break-up problem by using solitons [3]. A simpler solution is to use square optical pulses, in which the intensity across the pulse is constant, except for finite rise and fall times. Here we report the first application of femtosecond square pulses to avoid pulse break-up in alloptical switching. As a result we obtain enhanced power transfer and a sharper switching transition.
Observation of Optical Soliton Switching in an All-Fibre Nonlinear Sagnac Interferometer
Authors: Blow K.J. , Doran N.J. , Nayar B.K.
Published: February 2023

In this paper we describe an application for optical solitons in a configuration which can permit switching and logic operations on entire ultrashort pulses. The following is, we believe, the first experimental observation of the recently proposed soliton switching effect [1],[2].
Experimental Generation of 0.2 THz Fundamental Soliton Train in a Fiber with Varying Dispersion
Authors: Bogatyrev V.A. , Bubnov M.M. , Dianov E.M. , Kurkov A.S. , Mamyshev P.V. , Miroshnichenko S.I. , Rumyantsev S.D. , Semenov V.A. , Semenov S.L. , Sysoliatin A.A. , Chernikov S.V.
Published: February 2023

Generation of fundamental solitons at a high repetition rate in optical fibers is of great interest. Existent at present time methods permit to generate solitons at about 100 MHz repetition rate (see,e.g. review [1]). Hasegava [2] suggested a method for the generation of a train of pulses with the high repetition rate based on the effect of modulation instability of cw radiation in fibers. Tai et al.[3]were the first to realized this method. However, this method does not permit to generate a stable train of uninteracting solitons because of pedestal existence between the pulses. Iwatsuki et al.[4] observed soliton effects in fibers using 2.6 GHz gain-switched 1.3 μm laser diode. In [5,6] we suggested a method for the generation of a high repetition rate (up to THz range) stable train of practically uninteracting solitons. The method is based on the adiabatic amplification of a sin-modulated cw signal in a fiber (instead of amplification can be used fibers with slowly decreasing dispersion). In present paper we report the first experimental realization of this method.
Broadband Squeezing with Cotraveling Waves
Authors: Shirasaki M. , Haus H. A.
Published: February 2023

Squeezed states have been produced by degenerate parametric amplification and four-wave mixing[1−5]. In all these cases the squeezing was narrowband, because the mechanisms employed are inherently bandlimited. It would be desirable to construct a squeezing apparatus that is broadband, because then it could be applied to short optical pulses. Aside from the fact that optical pulses with reduced phase or amplitude noise are interesting in their own right, the use of optical pulses in experiments can eliminate many sources of noise that prevent effective squeezing of quasi cw excitations.
Nonlinear Propagation of Coherently Coupled Pulses Generated Through Four-Photon Mixing Processes
Authors: Liu Dun , Winful Herbert G.
Published: February 2023

In this paper we discuss the nonlinear propagation of three coherently coupled pulses interacting through the parametric four-photon mixing process in a dispersive fiber. An intense pump pulse whose wavelength lies near the zero group velocity dispersion (GVD) wavelength gives rise to a pair of Stokes and anti-Stokes pulses whose amplitudes grow from noise. The Stokes and anti-Stokes wavelengths are symmetrically disposed about the zero GVD wavelength and hence these pulses propagate with the same group velocity. Since the Stokes pulse lies in the region of negative GVD it experiences substantial compression through the combined effects of cross-phase modulation, self-phase modulation, and dispersion. The anti-Stokes pulse lies in the region of positive GVD, is much broader than the Stokes, and can propagate as a dark pulse. While phase-matched parametric interactions in the zero-GVD region have been studied before (Refs. 1-3), this paper is the first to fully incorporate nonlinear pulse propagation effects by solving a set of coupled nonlinear Schroedinger equations. The results are particularly relevant in view of the recent demonstration of a parametric soliton laser (Ref. 4).
Coherent Beam Combination in Integrated Optics
Authors: Shen T. P. , Rogovin D. , Boardman A. D.
Published: February 2023

The coherent beam combination, or two-wave mixing, in nonlinear waveguide is a new area of great importance in integrated optics. The coherent beam combination has been successfully demonstrated in the bulk nonlinear materials, e.g., photorefractive1 or nonlocal Kerr materials,2 for image amplification,1,2 spectroscopy,3 etc. It is expected to be as versatile in the waveguide context.4
Photo-Induced Enhancement of Second Harmonic Generation in Optical Fibres
Authors: Kashyap Raman
Published: February 2023

Phase-matched second-harmonic generation (SHG) in optical fibres has been studied by several workers [1] [2] [3]. The origin of the second-order non-linearity in a material which should be centro-symmetric is unclear. A model proposed recently[3] speculates that a third order interaction creates a spatially alternating static electric-field which orients defects and removes material symmetry. The periodic variation in the effective second-order nonlinearity χ(2) then allows phase-matching. Oullette et al [4] W have demonstrated the erasure of a phase-matching seeded grating [3] using blue or green Argon laser wavelengths. Recently, Fermann et al [5] showed alignment of defects by a strong external static electric-field applied to an optical fibre transmitting Ar+ radiation at 488 nm wavelength. Static-field alone [6] does not seem to ‘prepare’ the fibre, while irradiation with Argon light alone [5] seems to erase the grating. Unlike previously reported work, we show that radiation from an Ar+ laser operating at 514.5 nm on a single longitudinal mode (SLM) is sufficient on its own to enhance SHG of 1064 nm wavelength light from a Q-switched Nd3+:YAG laser in an elliptical cored fibre which is close to the phase-matched condition for one set of fundamental and second-harmonic modes.
Integrated Optical Parametric Oscillators
Authors: Suche H. , Hampel-Vogedes B. , Ricken R. , Sohler W. , Teichmann H.
Published: February 2023

Integrated optics offer the possibility to achieve large pump intensities even at low power levels and to maintain them along a considerable distance due to the confinement of the radiation as an optical mode. Therefore, very efficient optical parametric interactions can be expected in guided wave structures. Moreover, modal birefringence can in principle be utilized to compensate the material dispersion and in this way to achieve phase matching even in highly nonlinear but isotropic materials like GaAs [1].
Periodically domain-inverted lithium niobate channel waveguides for second harmonic generation
Authors: Webjörn Jonas , Laurell Fredrik , Arvidsson Gunnar
Published: February 2023

It is known that ferroelectric domain inversion can occur at the positive face when c-cut lithium niobate is treated at temperatures near the Curie-temperature [1]. Domain inversion has also been noted as a problem during waveguide fabrication based on titanium indiffusion, which requires high diffusion temperatures [2,3,4]. The titanium was seen to affect the inversion process.
Influence of annealing on the conversion efficiency for SHG by Cerenkov radiation from proton-exchanged LiNbO3 waveguides
Authors: Arvidsson G , Laurell F , Jaskorzynska B , Webjörn J , Loni A , Keys R W , De La Rue R M
Published: February 2023

By using integrated optical waveguides, high conversion efficiencies can be obtained for SHG at moderate power levels. The best results have so far been obtained with Ti:LiNbO3 waveguides [1,2]. The material birefringence is then utilized to fulfil the phase-matching condition. SHG using the fundamental wavelength ~ 0.8 μm, which is of considerable practical interest, cannot, however, be phase-matched in this way. The wavelength dispersion is in this case so large that it cannot be compensated for by the birefringence of LiNbO3. Promising results for SHG in proton-exhanged waveguides using semiconductor lasers at 0.84 μm wavelength have, however, been reported [3,4], with the frequency doubled light generated as a substrate mode, Cerenkov radiation. Conversion efficiencies have been reported [3], that are comparable to guided-guided wave interactions in Ti:LiNbO3 waveguides. The Cerenkov scheme benefits from the facts that the largest nonlinear coefficient d33 is used, and that proton-exchanged waveguides can be used, allowing strong mode confinement.
Second Harmonic Generation with Grating Excitation of Coupled Surface Plasmons
Authors: Simon H. J. , Chen Zhan
Published: February 2023

The properties of surface electromagnetic modes associated with multi-layer thin films continues to be a subject of interest. Particular attention has been given to the resonances associated with coupled surface plasmons which propagate on opposite sides of a thick metal film bounded by dielectrics with the same index of refraction. Of the two modes, corresponding to symmetric and antisymmetric magnetic field profiles, the former has a surprisingly low attenuation for a sufficiently thin metal film and has been named the long-range surface plasmon (LRSP) while the latter has been named the short-range surface plasmon (SRSP).(1) Recent attention has focused on the use of grating structures for coupling to the LRSP mode. Attenuated total reflectance (ATR) from a thin silver grating multi-layer structure has recently been reported.(2)
Limitations and Opportunities from Nonlinear Effects of Optical Fibers in Optical Communications
Authors: Aoki Yasuhiro
Published: February 2023

Since the early studies by E. P Ippen and R. H. Stolen [1], nonlinear optical effects in optical fibers have been studied extensively, and found useful applications such as wavelength conversion and pulse compression [2-5]. The fundamental fiber nonlinearities are the stimulated Raman scattering (SRS), stimulated Brillouin scattering (SBS), parametric mixing and self phase modulation, all of which come from the third order nonlinear polarization. Due to the high light intensity and long interaction length possible in low-loss single-mode optical fibers, these effects can be induced with relatively low pumping power levels [6,7]. For example, the SBS can occur in singlemode fibers with input powers less than 10 mW.
Operation of a Semiconductor Laser Pumped, Polarized, Single Mode All-Fibre Brillouin Laser
Authors: Bayvel P. , Giles I. P.
Published: February 2023

Stimulated Brillouin scattering (SBS) is an important nonlinear effect which is observed at very low powers in single mode optical fibres1. Although a limitation in the performance of coherent transmission systems, nonlinear SBS gain can be usefully exploited in applications such as fibre amplifiers2,3 and Brillouin lasers4,5.
Parametric Frequency Conversion in a Highly Birefringent Fiber
Authors: Chee J. K. , Liu J. M.
Published: February 2023

A wide variety of nonlinear optical phenomena, such as stimulated Raman scattering[1], stimulated four-photon mixing[2], and sum-frequency generation[3], have been observed in optical fibers. For four-photon mixing in a fiber, phase matching condition has to be satisfied as well as conservation of energy. This has been successfully demonstrated both in multimode and single-mode fibers[4,5]. In a single-mode birefringent fiber, the birefringence in the fiber can compensate for the material dispersion[6,7]. Four-photon parametric process in single-mode birefringent fibers has been observed by Stolen et al. [6] when the pump polarization was along the slow axis and the Stokes and anti-Stokes pair were generated with a polarization along the fast axis with a large frequency shift. Later, Stenersen et al. [7] reported four-photon mixing with a relatively small frequency shift in highly birefringent single-mode fibers by divided pump between different polarization modes and phase-matched totally non-degenerate four-photon mixing by the pump, Stokes, and stimulated Raman Stokes to generate a new frequency. In this paper, we report the observation of various third-order nonlinear optical processes following parametric four-photon mixing in a highly birefringent fiber.
Self-similarity of solitons in a nonlinear Fibonacci multilayered medium
Authors: Gupta S Dutta , Ray Deb Shankar
Published: February 2023

In a recent publication1 we have shown that in a nonlinear quasiperiodic system (consisting of nonlinear slabs A and B arranged in a Fibonacci sequence) switching between the states of low and total transmission is possible. In this paper we trace the origin of total transmission to the excitation of gap solitons2 in the structure. We also report the scaling properties of the solitons with respect to the system size and show that the solitons pertaining to strucures with different sizes are self-similar.
Leaky Waves Guided by Nonlinear Layers
Authors: Lin L. , Tamir T. , Leung K.M.
Published: February 2023

Rigorous analytical solutions for electromagnetic fields in the presence of layered media having nonlinearities of the Kerr type have been developed for guided surface waves1 and for incident homogeneous plane waves.2 In both cases, ideally lossless configurations have been assumed, i.e., all dielectric constants are real and the pertinent wavenumbers are either pure real or pure imaginary. However, work on guided leaky waves (having wavenumbers that are complex even in ideally lossless structures) has been limited to the case where the nonlinear region is semi-infinite.3 We therefore report here a general procedure for deriving leaky-wave fields supported by Kerr-type nonlinear layers of bounded thickness. These fields can be regarded as a new class of solutions, which serve as the nonlinear counterpart of leaky-wave modes along linear configurations. Although we derive leaky waves guided by a single nonlinear layer, our procedure can be readily generalized to any number of such layers, including semi-infinite ones, and possibly to nonlinearities other than the Kerr type.
Nonlinear Optical Switching in GaAlAs Waveguides
Authors: Valera J.D. , Goodwill D.J. , Walker A.C.
Published: February 2023

Previously reported observations of optical bistability in a GaAs/GaAlAs waveguide cavity included whole-sample thermally induced absorptive and refractive bistability [1] and localised (μs) thermally induced absorptive bistability [2]. Other groups have observed refractive bistability due to an optoelectronic mechanism in MQW GaAs/GaAlAs waveguides [3,4]. In this paper we report the observation of bistability due to thermally induced changes in leaky modes within a GaAs/GaAlAs waveguide and discuss the optimisation of optoelectronic nonlinearities in semiconductor guides of this type. A leaky planar waveguide consists of a low index layer bounded by two higher index layers. These exhibit radiative losses, where for the nth order mode the attenuation coefficient is proportional to (n+1)2 [5]. In this investigation the waveguides used were short enough to allow good transmission of the lower order modes.
Measurement of nonlinear-optical parameters in semiconductor doped glass waveguides
Authors: Dannberg P. , Bartuch U. , Possner T. , Bräuer A.
Published: February 2023

Semiconductor doped glasses (SDG) have gained considerable interest for nonlinear guided wave applications, because they show relatively large nonlinearities with ps-response times. Quantum size effects in SDG can possibly enlarge the nonlinearities.
Solitons in two tunnel coupled optical fibers
Authors: Abdullaev F.Kh. , Abrarov R.M. , Darmanyan S.A.
Published: February 2023

The investigation of optical soliton propagation in optical fiber waveguides attracts much attention due to the possibility to create high bit rate optical fiber communication systems (OFCS) as well due to the opportunity to work out varios elements of optical computers, sensors etc. on the basis of the transfer of information by solitons /1,2/. New opportunities open investigations of nonlinear process in coupled fibers. So in the case of stationary waves, as it shown in Mayer's papers (see for instance /3/), optical transistor and logical devices in the system of two coupled fibers can be created. Also such investigations help us to solve the problem of operation of the soliton parameters due to the coupling between fibers.
Degenerate Four-Wave Mixing in Planar Waveguides Consisting of Metal Particle Composites
Authors: Bloemer M. J. , Ashley P. R.
Published: February 2023

Materials with third order nonlinearities are useful for all-optical guided wave devices such as directional couplers and interferometric modulators [1]. Gabel et al [2] were the first to report Degenerate Four-Wave Mixing (DFWM) in planar waveguides with a nonlinear guiding medium. The waveguides were fabricated in semiconductor doped glass (Corning 3-69) by an ion exchange process. In the present paper we report DFWM in a planar waveguide consisting of gelatin doped with metal particles. Experiments by Hache et al [3] on gold colloids indicate a value of x(3) = 10−8 esu with response times of < 5 psec for gold microparticles. We have obtained conjugate reflectivities near 1% for gelatin waveguides doped with gold and silver microparticles.
Nonlinear Transmission in a Multiple Quantum Well Ridge Waveguide Structure Close to 1.55μm Wavelength
Authors: Fisher M.A. , Mace D.A.H. , Tothill J.N. , Monserrat K.J.
Published: February 2023

Nonlinear optical properties of semiconductor waveguides are interesting in a variety of all-optical devices such as switches and couplers. The materials concerned have quite strongly intensity-dependent optical properties close to their absorption edges1 due to band-filling by optically excited electrons and holes (n2 values greater than 10-8cm2W-1 have been reported in guided wave experiments2). The use of multiple quantum well (MQW) material gives considerable freedom in engineering optical devices since the position of the band edge can be tuned by control of the well width and the refractive index can be independently varied by control of the ratio of well to barrier thickness.
Radiation-Forces-Induced Nonlinearity and Bistability in Integrated Optics
Authors: Lukosz W.
Published: February 2023

In this paper I propose and analyse IO devices in which nonlinearity and bistability are caused by the radiation forces of the evanescent field of the guided modes exerted on an 'effective-index-shifting' element E, which is a micromachined, light-weight, movable, non-absorbing dielectric plate separated from the waveguide by a very small gap. The resulting nanometer displacements of this element E provide the nonlinearity of the effective refractive index N of the guided mode.
Guided-Wave Nonlinear Optics Research in the USSR
Authors: Dianov E.M.
Published: February 2023

Researches on nonlinear guided-wave phenomena have inherited the high level of investigations on nonlinear optics in the USSR. It is especially true concerning the theoretical works which are carried out in many scientific centers [1-10]. Here I shall mention some directions of theoretical work in this field.
Soliton Dynamics in Bimodal Optical Fibers
Authors: Caglioti E. , Trillo S. , Wabnitz S. , Crosignani B. , Di Porto. P.
Published: February 2023

As well known, the nonlinear Schrödinger equation (NLSE) describes the propagation of intense picosecond optical pulses in single-mode fibers.1 The NLSE is completely integrable by the inverse transform method,2 and predicts the existence of stable bound states (bright solitons) in the anomalous dispersion regime of a fiber. When long propagation distances or femtosecond pulses are involved, additional terms associated with dissipation, third-order dispersion, self-steepening and Raman self-pumping must be included as Hamiltonian perturbations to the NLS equation.3 These perturbing terms may induce instability and decay of multisoliton pulses.4
Observation of the Formation of an Optical Intensity Shock and Wave Breaking in the Nonlinear Propagation of Pulses in Optical Fibers
Authors: Rothenberg Joshua E.
Published: February 2023

A prominent class of phenomena in nonlinear wave propagation is that of shocks and breaking,1 which are known to occur in many diverse physical systems. Optical propagation in single mode fibers provides an excellent physical system for examining these phenomena because the propagation can be considered one dimensional, and is thought to be well described by the Nonlinear Schroedinger equation (NLSE). The possibility of so called optical intensity "envelope" shocks was first theoretically suggested by several researchers2-4 some 20 years ago. In the description of Ref. 3 a higher order nonlinear term was considered which results in an intensity dependent group velocity, but because they ignored the effects of dispersion, the shock formation proposed there has never been observed. Although, for optical pulses propagating in strongly nonlinear, dispersive near-resonant vapors, nsec observations of self-steepening have been reported.5 In addition, Hasegawa and Tappert6 have pointed out that the dark pulse solitary wave is in fact an example in the class of envelope shocks proposed by Ostrovskii.4
Ultralong Distance Soliton Transmission Using Erbium Fiber Amplifiers
Authors: Mollenauer L. F.
Published: February 2023

Long distance transmission using a chain of optical amplifiers is potentially much cheaper and faster than with conventional electronic regenerators. Erbium doped fiber amplifiers, with their low pump-power requirements, lack of pulse chirping, independence of gain on polarization, built in automatic gain control, and perfect compatibility with transmission fibers, have done much to make this "all-optical" approach truly practical. It can be shown, however, that the full capacity of such a system can be realized only by using solitons.
4x5Gbit/s optical time division multiplexed nonlinear transmission over 205km
Authors: Spirit D M , Wickens G E , Blank L C
Published: February 2023

In order to fulfil the demand for increasingly sophisticated and bandwidth intensive services, telecommunications operators will require flexible optical transmission networks which will operate at higher data rates than those installed to date. At present, the maximum data capacity of installed optical systems is limited by the bandwidth of the electronics in the terminal and repeater equipment (currently around 2.5Gbit/s). Optical wavelength [1] or time [2] division multiplexing techniques may be used to access data rates substantially over 10Gbit/s, offering a substantial increase in capacity. Both multiplexing techniques could be used in conjunction with switching in either the wavelength or time domains to allow increased network flexibility through, for example, the drop-and-insert function. Discrete erbium-doped fibre amplification is an excellent method of compensating for the loss of the transmission link, providing bit-rate independent amplification. However, the regenerative function of conventional opto-electronic repeaters is no longer available in fibre amplifiers: linear dispersion of the optical pulses now becomes a major system constraint. The availability of fibre amplifiers with excellent performance in the 1550nm window restricts the signal wavelength of optically multiplexed systems to this wavelength range, implying the use of dispersion-shifted transmission fibre. The operation of wavelength division multiplexed transmission with more than a few channels over fibre with low dispersion can lead to significant system penalties due to four wave mixing, even over fibre spans of less than 100km [3]. An alternative approach to ultra-high speed transmission is to use time division multiplexing, requiring a transmitter configuration based on short (≈ps) optical pulses. In this instance, nonlinear optical pulse compression in the transmission fibre may be used to advantage to significantly reduce (or even balance completely [4]) the linear dispersion of the optical pulses, permitting transmission well beyond the usual dispersion limit.
Stimulated Raman scattering in optical fibers: spontaneous initiation and spatial propagation
Authors: Hawkins Raymond J. , Stolen R.H.
Published: February 2023

Stimulated Raman scattering can be treated in either the frequency domain or the time domain. Traditionally, cw waves and long optical pulses have been treated in the frequency domain where the problem can be reduced to a set of coupled wave equations which include self and cross phase modulation as well as the Raman gain [1]. Frequency domain analysis, however, becomes intractable for ultrashort optical pulses where spectral bandwidths become comparable to the Raman frequency shift. Here a time domain approach is more appropriate.
The soliton self frequency shift in telecommunications fibre
Authors: Lucek J.K. , Blow K.J.
Published: February 2023

Pulses of duration 800 fs (sech2 FWHM) at 1550 nm are generated in an NaCl:OH laser having an actively stabilised external non-linear cavity [1]. These are coupled into lengths (several km) of standard telecommunications fibre (D=15 ps nm-1km-1, effective area = 75 μm2). The spectral and time domain information about the pulses emerging from the fibres is compared with the results of exact calculations. It has been shown that the magnitude of the soliton self frequency shift [2] (SSFS) in a given length of fibre is proportional to the inverse fourth power of the pulse width when a single soliton is launched [3]. However, the pulse-width(s) of the soliton(s) that form(s) from an arbitrary launched pulse depends on the pulse power and shape. Consider a pulse launched in the form A sech t.
Generation of Spatio-Temporal Patterns and All-Optical Switching based on Coherently Induced Modulational Instability in Fibers
Authors: Trillo S. , Wabnitz S.
Published: February 2023

The appearance of modulational sidebands building up from noise has been reported when an intense cw or quasi-cw propagates in a fiber in the anomalous dispersion regime [1]. The modulation transforms the input wave into a train of pulses with ultra-high repetition rate. This process may be stimulated by seeding incoherently (i.e., by means of a different weak detuned laser) the modulational instability (MI) [2]. However the experiments and the early theory on MI [3] have led to the diffuse but erroneous belief that in the presence of MI the input wave becomes a train of solitons. On the contrary (temporally) periodic wave solutions of the nonlinear Schroedinger (NLS) equation have shown that the propagation is periodic also in space (a phenomenon known as Fermi-Pasta-Ulam recurrence [4]), leading to the formation of complex spatiotemporal patterns [5-7]. We show here that the nonlinear dynamics of modulated waves, which includes in principle the interaction of an infinite number of Fourier modes, is essentially locked to the simple interaction between three modes: the pump and the first symmetric sidebands. In this case a simple integrable one-dimensional equivalent oscillator model [8-9] enables one to unfold the role of a coherent modulation at the input in the generation of the spatio-temporal patterns. This suggests also the possibility of new experiments in which the pulse train and switching among two logical state is controlled by the input phase relation between the pump and the sidebands.
Pulse Repetition-Rates in a Passive, Self-Starting, Femtosecond Soliton Fibre Laser
Authors: Richardson D.J. , Laming R.I. , Payne D.N. , Matsas V. J. , Phillips M.W.
Published: February 2023

Rare-earth doped optical fibres offer wide gain bandwidths and provide an ideal medium for the generation of ultra-short optical pulses. To date research in mode-locked fibre lasers has centered on active mode-locking schemes incorporating fast phase [1] and amplitude modulators [2]. However, the large non-linear effects obtainable in optical fibres make passive mode-locking an attractive proposition. A self-starting, passive mode-locking scheme based on the reflection properties of the Non-linear Amplifying Loop Mirror (NALM) [3] has recently been reported [4,5]. The system is capable of both picosecond/nanosecond duration square pulse operation [4] and ultra-short femtosecond soliton generation [5,6]. In this paper we discuss the various modes of operation of the laser and present results on pulse repetition rates, an important characteristic for a practical source of ultra-short solitons.
Noise in a passively mode-locked fiber laser
Authors: Ober M.H. , Hofer M. , Haberl F. , Fermann M.E.
Published: February 2023

Passive modelocking of fiber lasers has recently been shown to be a viable technique for the generation of ultra-short optical pulses[1,2]. In fact pulse-widths as short as 38fsec have been generated with such lasers to date[3], which compares well with pulse-widths obtainable with much more complex bulk laser systems[4–8]. However, for practical applications not only the pulse-widths generated with a particular oscillator are important, but also its radio frequency (RF) noise characteristics. From the RF-spectrum of modelocked oscillators information about the amplitude-noise and timing jitter of the generated pulses can be inferred[9–12]. Here we choose to investigate the noise characteristics of a fiber laser passively mode-locked by nonlinear polarization evolution[2,3] due to the simplicity of the involved experimental set-up and its superior performance in short pulse generation compared to other fiber laser passive mode-locking schemes involving a nonlinear amplifying loop mirror[1,13].