bluuebunny/crossref_metadata_2025 huggingface dataset:
Nonlinear optical properties of a single quantum well waveguide and a nonlinear asymmetric interferometer
Authors: Al Hemyari K. , Bhumbra B. S. , Ironside C. N.
Published: February 2023

The quantum well semiconductor laser has been shown to be the semiconductor laser of choice for efficiency and thereby high power applications. The key advantage of nonlinear devices fabricated in quantum well waveguides is that they can be easily integrated with quantum well lasers. Nonlinear optical effects in GaAs/AlGaAs quantum wells have been of considerable interest for sometime (see ref(1) for a recent review). In guided-wave formats some nonlinear devices have been demonstrated; a nonlinear directional coupler has been fabricated and characterised (2),(3) and a saturable absorber for a mode-locking semiconductor laser.(4) has also been demonstrated.
Grating Couplers for Kerr-Type Nonlinear Waveguides: A Simplified Theory
Authors: Reinisch R. , Vincent P. , Nevière M. , Vitrant G.
Published: February 2023

We consider grating induced optical bistability (OB) arising from the resonant excitation of a given nonlinear guided mode. In that case it can be shown, using the coupled-mode formalismi(1), that in the whole bistable domain : a) the transverse field map of the resonantly excited nonlinear guided mode corresponds to that of the associated linear one which is known. b) the Kerr-type nonlinearity only modifies the longitudinal wavevector component. Thus the rigorous theory of diffraction(2), previously used to study grating-induced plane wave OB(3), can be replaced by a much more simple one which works as follows : i) determine the complex longitudinal wavevector component of the linear leaky guided mode p, βpL, through the solution of the associated linear homogeneous grating problem(2), ii) use the rigorous theory of diffraction in linear optics(2) to determine the in-coupling efficiency, tp, of the incident plane wave, iii) use the coupled-mode formalism to derive the analytical expression(4) of the complex nonlinear longitudinal wavevector component βpNL.
Experimental Observation of Picosecond Dark Soliton Propagation Over 1km Fiber in the Near Infrared
Authors: Emplit Ph. , Hamaide J.-P. , Haelterman M.
Published: February 2023

In 1973, Hasegawa and Tappert predicted that the nonlinear refractive index of silica fibers can compensate for Group Velocity Dispersion (GVD), resulting in the so-called optical solitons which propagate without distortion.1,2 Both "bright" and "dark" solitons were identified that correspond to the negative and positive GVD regions of the spectrum, respectively. Since then, owing to their potential applications in high bit-rate fiber telecommunication systems, optical solitons have been intensively investigated both theoretically and experimentally. Soliton propagation of bright pulses has been verified in a large number of experiments and the possibility of its application in long haul fiber transmission has been demonstrated.
The Spatio-Temporal Dynamics of the Light Pulses in the Nonlinear Weak-Guiding Optical Waveguides
Authors: Melnikov L.A. , Bauer R.G.
Published: February 2023

The formation of the solitons owing to self-phase modulation (SPM) occurs at relatively small intensities [1]. In this cases the transverse team profite may be considered as very close to the spatial profile of the fundamental mode. For shorter pulses or larger intensity when n
2
I/Δn≅I (n
2
I is the nonlinear part of refraction index, Δn is She difference of core and cladding index) it is needed to include into consideration other thild-order effects such as self-focusing (SF) [2]. For the pulse parameters control it is interesting to investigate the transmission of the ultra-short pulses in periodical waveguides. In the step-index waveguides the transverse structure of fields is strongly dependent from excitation of modes of continuous spectrum of transverse wavenumber, and it is useful to derive the corresponding expressions.
Soliton Propagation in Media with Non-central Symmetry
Authors: Guo Qi , Liao Chang-jun , Lu Shong-hao
Published: February 2023

The second-order susceptibility χ(2) describes the energy transfer of second-order nonlinear optical effects in media with non-central symmetry. In the waveguides made of this kind of media, however, if the phase-matching condition is not satisfied, the effects are very weak in the propagation distance that the wave interaction length is much longer than the coherent length (the wave interaction length can be very long, when the guides have low loss.). It is theoretically demostrated here for the first time that the waveguides in this case can support the envelope solitons described by nonlinear Schrödinger equation (NLSE).
All-optical logic gates based on cross-phase modulation in a nonlinear fiber interferometer
Authors: Jeong J.-M. , Marhic M.E.
Published: February 2023

All-optical logic gates have been demonstrated using nonlinear waveguide devices. In such devices, optical fibers are increasingly used, since their optical Kerr effect is very fast, and their low-loss waveguide structure allows a long interaction length and relatively low power. For example, an AND gate based on intensity-dependent polarization rotation [1], XOR and AND gates based on soliton trapping [2], a NOR gate based on soliton dragging [3], and AND, NOT, XOR, and XNOR gates [4] have been demonstrated in polarization-maintaining fibers.
Observation of Polarization Switching and Pulse Break-Up in Spun Fiber
Authors: Ferro P. , Haelterman M. , Trillo S. , Wabnitz S. , Daino B.
Published: February 2023

The nonlinear directional coupler (NLDC) [1] is a promising element for ultra-fast all-optical signal processing. The experiments have demonstrated self-switching of light in fiber-optic NLDC's, such as dual-core fibers [2-3], birefringent fibers [4], and periodically twisted birefringent filters [5]. Fiber-optic nonlinear couplers exhibit an istantaneous Kerr-law response, which permits femtosecond pulse switching [3]. Whereas with fiber-optic switches the switching power is relatively high, owing to the weakness of the fused quartz nonlinearity.
Ultrafast All-Optical Polarization Switching Near Half the Band Gap in Semiconductors
Authors: Yang C. C. , Villeneuve Alain , Stegeman George , Lin Cheng-Hui , Lin Hao-Hsiung , Chiou I-Peng
Published: February 2023

In this paper, we present the experimental and numerical studies of nonlinear polarization switching in AGaAs and GaAs/AlGaAs multiple quantum well waveguides. In implementing nonlinear polarization switching, the goal is to induce a nonlinear change of linear polarization by π/2 at the output of a waveguide. When the waveguide eigenmodes (TE and TM) are equally excited at a lower power, modal birefringence results in different phase evolution of the two modes, leading generally to elliptical polarization at the waveguide output. In the experiment, a quarter- and a half-wave plates were used to bring the output polarization back to linear, parallel to the horizontal (TE mode) axis. At a high power, the interplay between self-phase modulation, cross-polarized cross-phase modulation, and oscillatory nonlinear coupling changes the output polarization state relative to the low power case. Complete switching is obtained when the polarization at the output is orthogonal to the low power case. In the intermediate case, the output polarization is at some angle relative to the horizontal axis and the output power is shared by the two polarization directions.
Generation of CW Fundamental Soliton Train Using Multisoliton Pulse Compression In A Varying Dispersion Fiber
Authors: Shipulin A. V. , Fursa D. G. , Golovchenko E. A. , Dianov E. M.
Published: February 2023

The sources of fundamental soliton trains with repetition rates of 10-100 GHz are of grate interest for fiber optic communication lines. A method for generation of such trains based on the double-frequency beating signal transformation in a Dispersion Decreasing Fiber (DDF) in the negative GVD region has been recently proposed [1]. Adiabatic compression of a signal into a train of fundamental solitons allows to create a CW source, generating at repetition rates of about 100 GHz [2,3]. Reduction of the lower limit of the repetition rate down to a few tens of GHz is highly attractive for soliton based communication lines of the nearest future. However the lower limit of the repetition rate Ω, that can be generated by this method is connected with the DDF length L suitable for practical application (L~1/Ω2 and for Ω<50 GHz L>10 km).
Nonlinear Hybrid Guided Waves in Birefringent Media
Authors: Torres Juan P. , Torner Lluís , Lederer Falk , Mihalache Dumitru , Baboiu Daniel M. , Ciumac Maria
Published: February 2023

Strongly nonlinear waves guided by planar structures containing low-loss dielectric media with an intensity-dependent refractive index have been extensively investigated during the last few years [1]. The growing interest on this subject comes from the unique waveguiding properties of such waves, with potential applications to all-optical waveguide devices for ultrafast signal processing and routing. At the present time, almost all investigations have been concentrated upon TE and TM-polarized waves taking place in isotropic structures. Transverse-polarized [2]-[3] and hybrid [4] waves propagating at the interface between isotropic nonlinear and linear gyrotropic media, with potential applications at the microwave frequency-band, have been also recently addresed. Here we report the, to our knowlegde, first investigation of strongly nonlinear hybrid waves guided by layered structures containing both birefringent crystals and isotropic nonlinear media.
Nonlinear Planar Waveguides with Graded-index Core
Authors: Sammut R.A.
Published: February 2023

Theoretical analysis of the wave equation in nonlinear, planar waveguides has revealed a rich variety of guided wave solutions, some of which may have practical applications1. The majority of analytical work in this area has been restricted to step index structures, since these are the only ones for which exact solutions are available. For more general structures, numerical methods can be used but, for nonlinear problems, these can sometimes be difficult to apply.
Grating-Assisted Nonlinear Codirectional Couplers
Authors: Little B. E. , Huang W. P.
Published: February 2023

The intensity induced nonlinearity of semiconductors and glasses have shown promise in the development of ultrafast all-optical switches[1]. The theoretical aspect of switching in ideal Kerr type nonlinear devices has drawn considerable attention since the introduction of the parallel nonlinear coupler by Jensen[1-3]. These devices included coherent couplers, polarization converters, transistors, and bistable feedback devices.
The Third Order Nonlinearity-A Factor Limiting High SH Efficiency In Optical Fibres
Authors: Zhao Yuxing , Town Graham , Sceats Mark
Published: February 2023

Second harmonic generation (SHG) in optical glass fibres [1] is an unexpected but nevertheless potentially useful nonlinear phenomenon. Optical fibres offer several advantages in SHG over other devices. Firstly the combination of a long interaction length together with the high intensity possible in a small core permits the relatively small non-linear effects in glasses to be effectively utilised. Furthermore, the self-writing process of SHG in optical fibres may provide an automatic phase matching [2] which is vital in any efficient wave-mixing process. However since observation of efficient SHG in fibres by Österberg [3], there has been very little progress in increasing the efficiency of SHG in fibres, with the highest reported efficiency to date being 13% by Farries et al [4]. Whilst many theories have been proposed as to this efficiency limit, we present here, for the first time, an investigation of the effects of the third order nonlinearity on the second harmonic generation efficiency.
Spatial Bright-Dark Soliton Interaction in Coupled Waveguides
Authors: Boardman AD , Xie K
Published: February 2023

Spatial solitons1 located in two different, non-identical slab waveguides (Fig.1) will be investigated. The guides are close enough to be coupled and because we are dealing with spatial solitons, guide 1 consists of a self-defocusing medium and guide 2 consists of self-focusing material.
Theoretical Analysis of Soliton Transmission with Sliding Filters
Authors: Kodama Y. , Wabnitz S. , Romagnoli M. , Midrio M.
Published: February 2023

Theory and experimemts have shown that the insertion of bandpass filters after each amplifier in optical fiber transmission links may increase the stability of the soliton pulses with respect to the amplifier noise induced time jitter [1-4]. A substantial improvement to the stability of soliton transmissions may be achieved by slowly sliding the center frequency of subsequent filters along the transmission line [5].
Interaction of vector solitons
Authors: Afanasjev V. V. , Serkin V. N.
Published: February 2023

Active interest is taken in polarization and two-wavelength phenomena in soliton propagation. Among intriguing experimental results are the polarization multiplexing [1], soliton logic [2], polarization intensity discrimination [3], polarization mode-locking [4,5], bound state of dark and bright optical solitons [6]. All these effects may be describes (at least qualitatively) by the vector Nonlinear Schrödinger equation (NLS) (1). This equation has a rich variety of solutions, and a lot of stationary (soliton) solutions were found by different analytical approaches (see [7] and references therein).
Soliton-like pulses governed by fourth order dispersion in optical fibers
Authors: Karlsson Magnus , Höök Anders
Published: February 2023

Intense picosecond-pulses in optical fibers are well known to be described by the nonlinear Schrödinger (NLS) equation, which includes second order (group-velocity) dispersion, GVD. When studying ultrashort pulses, however, higher order dispersive terms must be taken into account. Specifically, at carrier frequencies of maximum (minimum) GVD, the extensively studied third order dispersion[1], vanishes, and the effects of negative (positive) fourth order dispersion, 4OD, become important.
The influence of non-linear polarisation rotation on the mode-locking dynamics of an Er fibre laser.
Authors: Davey R. P. , Langford N. , Ferguson. A. I.
Published: February 2023

Rare earth doped fibre lasers have recently been investigated as sources of ultrashort pulses. Several different mode-locking mechanisms have been investigated [1-3]. Recently several research groups have observed the passive mode-locking of Er fibre lasers using an effective fast saturable absorber based on non-linear polarisation [3,4]. Pulses as short as 180 fs have been directly generated from an Er fibre laser by exploiting this process [5]. In this presentation we identify and quantify the role of non-linear polarisation in the modelocking dynamics of a hybridly mode-locked Er fibre laser.
Interpretation of the effect of reduction of soliton interaction by bandwidth limited amplification
Authors: Afanasjev V.V.
Published: February 2023

A lot of possible applications of solitons for all-optical logic and high-bit rate transmission lines makes the problem of soliton interaction a very important aspect of the study of soliton propagation and amplification in optical fibers. In particular, soliton-soliton interaction limits bit rate of soliton communication systems and therefore reduction of soliton interaction is a very promising proposal. It was discussed recently by different authors that the interaction strength might be substantially reduced or fully suppressed by the bandwidth-limited gain [1-5]. At the same time, the bandwidth limited amplification is already being used in soliton communication systems for reduction of Gordon-Haus jitter [6,7] and noise suppression [8]. So, it is potentially possible to increase the bit rate by the simply changing the parameters of spectral filtering and small additional amplification. But the explanation of this effect is the subject of discussion. Different theories were proposed; however, there is no satisfactory approach to explain this effect for arbitrary soliton phases and to give a quantitative agreement with numerical simulations. Treating this problem as a very important one, here we present numerical results along with an analysis of IST eigenvalues and modified equation for soliton center.
Induced nonlinear modulational instability in high birefringence fibers: a quantitative study
Authors: De Angelis C. , Santagiustina M.
Published: February 2023

Modulational instability (MI) refers to the growth of an initial weak perturbation at the expense of a plane wave in a dispersive or diffractive nonlinear medium [1]. In the context of optical fibers, temporal MI in the anomalous group-velocity dispersion (GVD) regime has been extensively studied in recent years for its potential application in high-repetition rate ultrashort pulse train generation [2] and ultrafast optical switching [3]. The domain of MI may be extended to the normal GVD regime by means of a feedback loop [4] or exploiting cross-phase modulation (XPM) [5,6]. In the latter case, the simultaneous presence of two copropagating beams can also lead to a more complex behaviour in comparison with the scalar case [7]. The aim of this paper is to give a quantitative understanding of the nonlinear dynamics (i.e. past the early stage of exponential sidebands growth) of MI induced by XPM between linearly polarized beams copropagating along the principal axes of a high-birefringence fiber, both weakly perturbed. At first, for the sake of clarity, we will recall the well known linear stability analysis of the system and then introduce a finite dimensional truncation leading to an intricate system of Ordinary Differential Equations (ODE’s). Finally, introducing some approximations supported by numerical results and physical considerations, we will obtain an exactly solvable set of ODE's, which is analogous to the one derived in [7] for a different initial condition.
Switching and Optical Bistability with Counter Propagating Waves in Nonlinear Bragg Waveguides
Authors: Peschel T. , Peschel U. , Lederer F.
Published: February 2023

Within the past several years there has been a considerable interest in the investigation of optical bistability in nonlinear planar resonators.
Аll-Optical Signal Regenerator
Authors: Lucek J. K. , Smith K.
Published: February 2023

All-optical processing is the key to overcoming electronic bottle-necks in high-speed communication networks. Such systems, which are likely to include an abundance of fibre amplifiers, are still limited in performance by timing jitter (the Gordon-Haus effect1) and signal to noise degradation due to the build up of amplified spontaneous emission. The use of all-optical signal regeneration to restore pulse timing and to remove noise and intensity fluctuations could therefore greatly extend the range and bit-rate of such a system. Here, we demonstrate experimentally a complete all-optical signal regenerator exploiting a novel method of all-optical clock recovery2 and a nonlinear loop mirror3. We show that the regenerated data has less intensity variation and less temporal jitter than the incoming data.
Sub-tera bit/s WDM pulse generation utilizing LD-pumped supercontinuum in optical fibers
Authors: Morioka T. , Mori K. , Kawanishi S. , Saruwatari M.
Published: February 2023

Multi-wavelength optical sources are a great demand to construct future ultrafast flexible WDM networks. So far, multi-wavelength DFB laser-diode arrays [1], [2] and multiwavelength mode-locked fiber ring lasers with a novel birefringent-cavity have been reported [3]. Recently, another multi-wavelength pulse generation technique utilizing supercontinuum has been demonstrated using a strong Nd:YLF laser pulse at 1.3 μm [4]. This paper reports, for the first time to our knowledge, the laser diode (LD)-pumped supercontinuum (SC) generation in the GHz regime at 1.5 μm and demonstrates a sub-tera bit/s WDM pulse generator that outputs 1.2 nm-spaced, more than 40-wavelength-channel, 5-10 ps pulses at 6.3 GHz.
Stress-Induced Domain Inversion For Quasi-Phase-Matched Second Harmonic Generation in KTP Waveguides
Authors: Buritskii K.S. , Chernykh V.A. , Dianov E.M. , Maslov V.A. , Shcherbakov E.A.
Published: February 2023

One of the ways in the development of the compact blue-green lasers is frequency doubling of near-IR semiconductor laser in nonlinear crystal, in particular, using quasi-phase matching (QPM) in waveguides. QPM was realized by the periodic domain inversion in the several ferroelectric crystals, such as LiNbO LiTaO3 and KTP [1-3]. Various domain inversion techniques were proposed to get efficient SHG in the waveguide geometry, but basically for LiNbO3 and LiTaO3 crystals. Only one method based on the Ba2+ + Rb+ ion exchange through the periodical mask was applied for KTP [3].
Blue light second harmonic generation in KNbO3 waveguides
Authors: Fluck D. , Pliska T. , Günter P. , Fleuster M. , Bauer St. , Buchal Ch.
Published: February 2023

We report efficient optical frequency doubling from the near infrared into the blue spectral range in KNbO3 planar and channel waveguides produced by He+ ion implantation. Two configurations have been investigated: (i) guided mode phase-matched and (ii) Cerenkov-type second harmonic generation where the second harmonic is radiated into the substrate.
Dark soliton steering in a saturable nonlinear medium
Authors: Krolikowski Wieslaw , Xiaoping Yang , Luther-Davies Barry , Breslin John
Published: February 2023

Since their discovery [1,2], dark soliton have been attracting growing interest.
Studies on Novel Photoselectable Organic NLO-Molecules
Authors: Eich Manfred , Sprave Martin , Mauermann Heike , Stein Stefan , Müllen Klaus , Frank Werner , Tschudi Theo
Published: February 2023

NLO-chromophores of the azobenzene type and of the stilbene type have been used either as dopants or as sidegroups in polymers in order to realize NLO-materials in which the refractive index and the nonlinear susceptibility could be modified optically.1,2 These changes are based on the photochemical transformation of these molecular units from the elongated trans state to the bent cis-state. Since the trans state is the thermodynamically stable state, the cis-isomers generally undergo a thermally activated relaxation back to trans even below the glass transition temperature.3
Assessment of Polymeric Materials for Nonlinear Optics
Authors: Bjorklund Gary C.
Published: February 2023

Organic nonlinear optical (NLO) materials offer the advantages of high intrinsic figures of merit for a number of useful nonlinear optical processes, low dielectric constant, moderate required processing temperatures, and the ability to use molecular engineering to modify a host of secondary properties {1}. In polymer form, organic NLO materials have important advantages for fabrication of complicated multilayer optical waveguide structures on large, low cost substrates and offer the potential for integration with conventional electronics components {2}. In this talk, applications of polymeric NLO materials for frequency doubling, electro-optic modulation and switching, photorefraction, and photonic switching will be considered.
A Novel Nonlinear Optical Waveguide Structure Using an LB Film
Authors: Asai N. , Fujiwara I. , Tamada H. , Seto J.
Published: February 2023

We propose a novel structure for an optical waveguiding layer to achieve efficient second harmonic generation (SHG) in the form of Cerenkov radiation, that is, the nonlinear optical susceptibility (χ(2)) inversion structure in the thickness direction (NIST). We also experimentally demonstrated, for the first time, an enhancement of 20 to 30 times for the efficiency of Cerenkov radiation SHG of a YAG laser due to NIST using 2-docosylamino-5-nitropyridine (DCANP) Langmuir-Blodgett (LB) film1, 2) as a waveguiding layer.
Determination of Spectral and Temporal Response of Various Ultrafast Optical Nonlinear Processes in Polydiacetylenes
Authors: Kobayashi Takayoshi , Yoshizawa Masayuki , Hattori Yasuhiro
Published: February 2023

Time evolutions of photoexcitations in several poly diacetylenes (PDAs), which attracted great interest in recent years because of their large and fast optical nonlinearities, were investigated by femtosecond absorption spectroscopy [1-4]. Here in this paper we for the first time could resolve four different nonlinear optical responses in PDAs both time and frequency dependence.
A New UV Nonlinear Optical Crystal — KBBF
Authors: Chen Chuangtian , Wu Baichang
Published: February 2023

One of the major aims scientists are now facing in nonlinear optical (NLO) material area is the search for new UV NLO materials, in which phase-matching below 200 nm can be achieved. On the basis of the anionic group theory, it was found that if the dangling bonds of (BO3)3- group are eliminated by linking with other groups, the band gap of (BO3)3- group can shift to as short as 150 nm. On the other hand, the (BO3)3- group is also favorable to produce a relatively larger birefringence and microscopic

χ

ijk

(
2
)

coefficients [1]. It was these novel ideas that motivated our group to make extensive efforts, which led to the successful discovery of another new UV NLO crystal — KBe2BO3F2 (KBBF).
Large-scale integration of electro-optic polymer devices
Authors: Lytel R. , Lipscomb G.F. , Ticknor A.J.
Published: February 2023

Organic electro-optic (EO) polymer materials offer exciting new opportunities in integrated optics. The electronic1 EO effect in organic materials yields large EO coefficients, low dispersion, and low dielectric constants.2 EO polymer materials have been modulated flat to 40 GHz and exhibit few fundamental limits for ultrafast modulation and switching. Polymeric integrated optic materials also offer great fabrication flexibility. The materials are spin-coatable into high quality, multilayer films, and can be patterned, metallized, and poled. Channel waveguides and integrated optic circuits can be defined by the poling process itself3, by photochemistry of the EO polymer4-5, or by a variety of well understood micro-machining techniques. Multi-layer integrated optic waveguide structures can be fabricated in much the same manner as Si-substrate, multilayer multichip modules. To date, EO polymer materials have been used to fabricate high-speed Mach-Zehnder modulators6, directional couplers7, Fabry-Perot etalons8, and even multitap devices9.
Electric-Field-Controlled Diffraction in Photorefractive Strontium Barium Niobate
Authors: Wilde Jeffrey P. , Hesselink Lambertus
Published: February 2023

Photorefractive gratings stored in single-crystal strontium barium niobate (SBN) are shown to provide electrically controlled diffraction. The diffraction can be temporally modulated by applying a time-varying electric field along the c-axis. This effect arises as the result of large nonlinear electro-optic and dielectric effects near the diffuse ferroelectric phase transition, which is around 30°C for SBN:75 and 70°C for SBN:61. Measurements are provided for SBN:75 that verify a simple model of the field-dependent diffraction.
Quadratic Nonlinear Optical Coefficient of AlxGai-xAs Thin Film
Authors: Ohashi M. , Kondo T. , Ito R. , Fukatsu S. , Shiraki Y. , Kumata K. , Kano S. S.
Published: February 2023

Recently there has been considerable interest in surface-emitting second-harmonic (SH) generators fabricated from the AlxGa1-xAs system.1,2) No systematic data are available, however, on the d coefficients of AlxGa1-xAs1,3,4) A major reason for this is that many interesting semiconductors, including AlxGa1-xAs, are obtainable only in the form of a thin epitaxial layer. Furthermore, the substrate is often absorptive at SH frequencies. We have developed a new method for characterizing the optical nonlinearity of such thin-film materials on the basis of the method of reflected harmonics.5) The new method has been applied to the determination of the coefficient d14 of AlxGa1-xAs as a function of x, the AlAs composition of the alloy semiconductor.
Electric Field Response of SHG Coefficient in Dye Doped Poled Polymer
Authors: Yonetani Akinori , Haga Hiroshi , Yamamoto Sadahiko
Published: February 2023

Nonlinear optical devices based on integrated optics or guided-wave technology are very attractive because of their advantages such as phase matching by variety of techniques and large light intensity due to small cross-section of waveguides. Although certain organic materials has large nonlinear optical susceptibilities, organic crystals are too fragile to make a waveguide. On the other hand, poled polymer films, which can be coated and patterned photolithographically, are useful material to make guided-wave devices. In several types of poled polymers, doped polymers (polymers doped with nonlinear optical molecules) are convenient to prepare. There are however several problems such as limited solubility of the nonlinear molecules in a polymer matrix and a rather fast relaxation of the induced optical nonlinearity obtained from poling in an electric field. As for methods to maintain the nonlinearity, covalent bonding approach [1] and cross-linked polymer[2] has been reported. These approach are very attractive to reduce the orientational disorder in poled polymers. The orientational disorder is however intrinsic in any amorphous material like poled polymers. It is therefore very important for practical devices to use some other method for maintaining the nonlinearity in poled polymer. It is also important for especially Electro-Optic devices to clarify the electric field dependence of nonlinearity in poled polymers.
Femtosecond Nonresonant Nonlinear-optical Response of CuCl Quantum Dots in Glass
Authors: Justus B. L. , Ruller J. A. , McMorrow D. , Melinger J. S.
Published: February 2023

The nonlinear-optical (NLO) properties of semiconductors confined in three dimensions, often called semiconductor quantum dots, have been the subject of intense study. Semiconductor doped glasses can be fabricated which exhibit quantum size effects due to the confinement of the photoexcited carriers by the insulating glass matrix. We have previously reported the fabrication1 of Cu(I)Cl quantum dots in a borosilicate glass matrix with radii ranging from 20Å to 35 Å and the measurement2 of the third order nonlinearity of the CuCl quantum dots due to saturation of the excitonic absorption at 380 nm. The CuCl quantum dots exhibit an extremely large, size dependent, nonlinearity at resonance. In this paper we report the femtosecond dynamics of the third order NLO response of CuCl quantum dots in borosilicate glass measured in a transparent region of the glass far from resonance. The measurements were performed with 90 femtosecond time resolution (60 fsec pulses) using a four wave mixing configuration which is capable of separating the electronic and nuclear contributions to the NLO susceptibility3.
Excess Noise Introduced by Beam Propagation Through an Atomic Vapor
Authors: Kauranen Martti , Gaeta Alexander L. , Davis William V. , Boyd Robert W.
Published: February 2023

We propose and show experimental evidence of a mechanism that is important in reducing the amount of noise reduction that can be achieved at low (<100 MHz) frequencies utilizing atomic vapors as the nonlinear medium.1 The mechanism is based on the two-beam-coupling gain2 experienced by the vacuum sidebands of a weak probe wave as it interacts with a strong degenerate pump wave in an atomic vapor. The mechanism leads to the amplification of intensity fluctuations of an initially shot-noise-limited probe field.
Temporal Modulation of Spatial Optical Solitons: A Variational Approach
Authors: Michinel Humberto , de la Fuente Raúl , Liñares Jesús
Published: February 2023

Spatial optical solitons are self-trapped optical beams that propagate without changing their spatial shape. This behaviour is caused by the competing effects of diffraction and selfocusing in a non-linear medium. Zakharov and Shaba(1) explained the connection between self-trapping and soliton theory. They also showed the complete analogy between temporal solitons, in wich the nonlinear phase modulation balances dispersion and spatial solitons in wich the non-linear index profile balances diffraction.
Tunability of an optical parametric oscillator by injection-seeding: nonlinear optical and spectroscopic applications
Authors: Haub J. G. , Johnson M. J. , Barth H.-D. , Orr B. J.
Published: February 2023

The performance and reliability of optical parametric oscillators (OPO) has improved markedly with the availability of high-quality pump laser sources and of new nonlinear optical materials, such as β-barium borate (BBO).1,2 This yields enhanced OPO conversion efficiency and output power over a wide tuning range. For instance, we have shown3 that a BBO OPO, pumped by pulsed 355-nm radiation from a single-mode injection-seeded Nd: YAG laser, can attain a total (signal + idler) output pulse energy of ≥100 mJ throughout the tuning range 430 nm −2.0 µm, with maximum conversion efficiency >60%.
Second-harmonic probing of the Si(100) - SiO2 interface on flat and vicinal Si(100): interfacial structure and step binding sites
Authors: Bottomley D.J. , Lüpke G. , van Driel H. M.
Published: February 2023

Of the various surfaces of crystalline silicon, Si (100) is industrially the most important and the formation of a stable oxide on this surface has allowed it to be used as the dominant material in modern semiconductor technology. Recently there has been a great deal of interest in steps on vicinal Si (100) since they are seen to play a central role in various chemical and physical processes including epitaxial growth, catalysis and oxide formation [1,2]. The study of stepped surfaces of Si (100) to date has been carried out primarily by conventional surface science techniques such as those based on electron diffraction or scanning tunneling microscopy, which normally require ultra high vacuum (UHV). However, over the last few years it has clearly been demonstrated that surface second harmonic generation (SHG) can be sensitive to the surface-vacuum interface as well as buried interfaces and can be used ”in situ” in various types of environments [3]. Our group and others have also shown that SHG can also be senstive to the presence of steps on oxidized or bare solid surface [4].
Quantum Theory of Electromagnetically Induced Transparency
Authors: Walls D.F. , Gheri K.M.
Published: February 2023

There have recently been several experiments which have observed electromagnetically induced transparency in atomic systems(1,2) This is based on the population trapping which may occur when two lower states are coupled to a common upper state by two laser fields. Due to destructive quantum mechanical interference this gives rise to a nonabsorbing resonance. Thus a strongly absorbing atomic transition may be rendered opaque.
Physics of Optically Generated Transient Electronic Defect States in KDP
Authors: Lee Howard W. H. , Davis Jeffrey E. , Hughes Robert S.
Published: February 2023

The wide bandgap (≈ 9-10 eV) of potassium dihydrogen phosphate (KDP) provides its wide transmissive properties throughout much of the near ultraviolet (UV) and infrared (IR), making KDP an extremely useful nonlinear material. However, the optical properties of KDP under intense optical excitation in the UV is a relatively unexplored, yet important issue. We studied the interaction of intense picosecond and subpicosecond UV laser pulses (GW/cm2) with KDP. Our intention was to study the dynamics and spectroscopy of optically generated defect states that may arise. We further addressed a ten-year old problem concerning the low conversion efficiency in KDP of 532 nm photons to 266 nm photons at high pump intensities.
Self-pulsing, Spectral Bistablilty, and Chaos in a Semiconductor Laser Diode with Optoelectronic Feedback
Authors: Lee Chang-Hee , Shin Sang-Yung
Published: February 2023

Effects of optoelectronic feedback on the dynamics of the semiconductor laser diode have attracted considerable attention. The optoelectronic feedback is utilized to generate optical short pulses[l] or to realize optical bistable devices[2]. In this paper we report self-pulsing, subharmonic generation, bistability, and chaos in a stable laser diode with delayed optoelectronic feedback.
Soliton switching in a dual-core active fiber nonlinear coupler.
Authors: Abdullaev F. Kh. , Darmanyan S. A. , Goncharov V.
Published: February 2023

We consider all-optical switching phenomena for solitons in the dual-core nonlinear coupler with amplification. The switching characteristics for soliton case are found. It is shown that Raman effect inhibits the switching conditions.
Low Threshold Optical Bistability and Differential Amplification using a Fiber Amplifier in a Nonlinear Ring Resonator
Authors: Muriel Miguel. A. , Fraile-Peláez Francisco J. , Capmany Jose
Published: February 2023

Optical fiber ring resonators using directional couplers as signal tapping elements are called to play an important role in the future all-optical communication and sensor networks. The possibility of obtaining a wide range of strutures capable of performing wide-band signal processing operations in a guided-wave format has attracted the interest of several research groups. Initial effort focused on structures operating under linear regime showing and demonstrating potential applications as fiber sensors [1], all-fiber lasers [2], Fabry-Perot and Mach-Zehnder interferometers [3], [4], and optical filters for WDM and OFDM [5].
Dynamics of Speckled Beam Phase Conjugation Self-Starting Process
Authors: Khoo I. C. , Bel’dyugina N. , Li Hong , Mamaev A. V. , Shkunov V. V.
Published: February 2023

Self-starting phase conjugation processes have been theoretically and experimentally studied in various contexts1–2, for open resonator, semilinear mirror, double phase conjugator, etc. In particular, as in the study of laser oscillations and resonators, the threshold conditions and the build up dynamics are of fundamental as well as applied importance.
Phase Locking Lasers viaPhase-Conjugate-Coupled Multimode Optical Fibers
Authors: Gruneisen Mark T. , Chakmakjian Stephen H. , Seeberger Edward D.
Published: February 2023

The combined properties of phase conjugation and optical fibers offer a novel solution to some problems associated with phase locking lasers. The task of coupling light from the lasing mode of one laser to the lasing mode of another laser can be simplified by making use of optical phase conjugation to achieve automatic mode matching. Double phase conjugation has been demonstrated to be particularly well suited to this task,1–3 since the process provides mode matched coupling between two sources that are mutually incoherent. Thus, coupling can be established without requiring the lasers to be phase locked a priori. Optical alignment can be further simplified by propagating the coupling beams through optical fibers. In addition to eliminating steering optics from the geometry, fibers provide an optical path for the coupling beams that is isolated from environmental effects. This isolation should reduce phase fluctuations in the coupled outputs that are caused by path-length fluctuations in the coupling arms.
Study on Optical Dephasing of Localized Exciton in a-Si 1-xCx: H With Incoherent Light
Authors: Zhou D.J. , Qiu G. , Fu C.H. , Huarig Z.Z. , Li Q.X.
Published: February 2023

In recent years, optical dephasing in disordered semiconductors and related alloys has been the interesting subject of nonlinear optics.
Additive Pulse Mode-Locking and Fiber Lasers
Authors: Haus H. A. , Ippen E. P.
Published: February 2023

Additive Pulse Mode-Locking (APM) is a particularly convenient means of generating pulses from fiber lasers, The figure eight self-stabilized laser by Duling is an example. Here the fiber ring(s) act as the pulse forming elements. It is desirable to construct simpler modelocking structures within one self-stabilized fiber resonator. Such structures are theoretically possible. They operate by nonlinear polarization rotation and use polarization transformers and polarizer(s), all compatible with, and realizable within, the gain fiber. They can be self-starting. Details of such designs will be given. One of these is being pursued experimentally at MIT. The aim is to adjust the parameters so as to produce a single soliton-like pulse bouncing back and forth in the resonator; the bandwidth limiting by the gain and loss profiles compensated by the APM action. It turns out that the APM action coupled with steady state gain saturation "quantizes" the solitons, giving them a characteristic energy. Therefore, in such fiber systems, one often encounters multiple solitons of equal energy bouncing back and forth as seen by the group at Strathclyde. We shall present the theoretical framework for the description of such systems.
Femtosecond Laser Pulse Compression by an Organic Crystalline Fiber
Authors: Yamashita Mikio
Published: February 2023

Compression of femtosecond optical pulses using a single-mode fused silica fiber (glass fiber) always needs high amplification of laser output pulses because of a low nonlinear refractive index n2 G of its fiber.1) This leads to some problems concerning the pulse stability in time and space, the pulse repetition rate, the optical damages to the glass fiber, and the precise adjustment of a big amplifier system. In order to solve these problems we inverstigated femtosecond-response, highly third-order nonlinear organic crystalline fibers.
Nonlinear Spectroscopy
Authors: Schawlow Arthur L.
Published: February 2023

Some incidents in the development of nonlinear spectroscopy will be recalled and compared with the present status and prospects.
Selective control of nonlinear optical conversion with Kerr media in bulk and fiber configuration
Authors: Zhou J. Y. , Cai Z. G. , Zhang G. S. , Wang H. Z.
Published: February 2023

Nonlinear optics is characterized with the conversion nonlinearly proportional to the pump intensity. This conversion, on the one hand, may be increased by using an intense light beam to excite a medium. On the other hand, various nonlinear optical processes may compete with each other. Thus study of the nonlinear competition is of both theoretical and pratical importance.
Nonlinearity in Fluoride Glass Single-Mode Fibers for Optical Communication
Authors: Osborne Robert
Published: February 2023

The low projected attenuation loss of fluoride glass down to 0.02 dB/km in the wavelength region around 2.5 μm has motivated the development and characterization of fluoride fiber, in particular ZBLAN-based fiber, for use in long-range optical links. At this attenuation value, repeaterless systems up to approximately 500 km in length should be realizable while undersea or transcontinental links would still require a few repeaters for attenuation and/or dispersion compensation. Analogous to silica fibers, the fiber nonlinearity may be employed as a means of overcoming the dispersion limitation to the maximum achievable bitrate through soliton pulse propagation while stimulated Raman scattering is capable of supplying distributed gain over a broad frequency range in both linear and nonlinear systems. The soliton-based system places, however, comparatively stringent demands both on the soliton source and on the distance between repeaters to maintain the soliton energy and stability. After presenting the relevant physical properties of the fiber, this work therefore first questions the viability of soliton versus linear pulse transmission for communication purposes in fluoride fiber by comparing their single-channel information carrying capacities.
Nonlinear TE Guided Wave Solutions for Alternating Self-focusing and Self-defocusing Layers
Authors: Skinner S. R. , Miranda J. , Andersen D. R.
Published: February 2023

The dispersion characteristics of nonlinear waveguides consisting of one or more dielectric layers possessing an optical Kerr nonlinearity is of great current interest. This is a result of the potential for device applications inherent in such waveguides. Guiding structures consisting of various self-focusing, or self-focusing and linear layers have been the most widely studied (for a recent review see Ref. [1]); the problem consisting of two semi-infinite self-defocusing layers has been only recently addressed [2]. In this paper, we present new results for a hybrid multilayer waveguide comprised of alternating self-focusing and self-defocusing layers. Eigensolutions for the multi-layered structures are obtained and analytic and numerical stability issues are discussed.
Nonlinear Effects in Dye-Doped Liquid Crystal Waveguides
Authors: Abbate G. , De Stefano L. , Mormile P. , Scalia G. , Santamato E.
Published: February 2023

In the nonlinear optics of Liquid Crystals (LC) a new chapter has been opened by the recent discovery that the addition of a small amount of organic dyes, less than 1%w/w, can greatly enhance the LC optical response. In the presence of the dye dopant, the optical torque exerted by light on LC molecules, which is responsible for the nonlinear behaviour, is magnified by a factor η, depending on the dye-LC mixture, on the dye concentration and on the wavelength. This factor may be up to 100 and both positive and negative in sign, leading to both focusing and defocusing nonlinearities1. This property can be attractive in designing nonlinear optical waveguides, at least for the realisation of quasi-static devices, for which no care is due to the time response. We developed a general model to describe both the light propagation inside the waveguide and the LC response to the guided light, in the plane wave approximation2.
Ultrafast Optical Nonlinearities in CuxS Nanocrystals
Authors: Klimov Victor I. , Karavanskii Vladimir A.
Published: February 2023

Three-dimensional (3D) carrier confinement in semiconductor nanocrystals (NC's) results in size-dependent photoluminescence and absorption spectra and significantly modifies the nonlinear optical properties and carrier dynamics with respect to those in bulk materials. So far, most experimental and theoretical studies have concentrated on NC's formed by direct-gap II-VI semiconductors such as CdS and CdSe. Recently, we reported the preparation, linear and picosecond nonlinear transmission of NC's of a new type: NC's formed by different copper sulfide phases [1]. Depending on the copper deficiency, the energy band gap in copper sulfide varies from 1.2 (x = 2) to 1.5 eV (x = 1.8) with an accompanying transformation of the semiconductor from indirect-gap to direct-gap one. These interesting properties as well as a small electron mass provide the broad phase/size controlled tuning range and give the opportunity to compare the effects of 3D confinement on nonlinear optical proterties in direct and indirect-gap semiconductors.
Second-Order Nonlinear Optical Properties of Wide-Bandgap Semiconductors
Authors: Kondo Takashi , Morita Kaoru , Ito Ryoichi
Published: February 2023

There have been growing interest in III-V semiconductors as promising nonlinear optical materials for frequency conversion devices. These devices are based on quasi-phase-matching that is achieved by spatially modulating large quadratic optical nonlinearities of semiconductors [1–5]. In order to exploit the large nonlinearities of semiconductor epitaxial films, we have developed two methods to determine the nonlinear optical coefficients of thin films by reflected second-harmonic measurements [6,7], In this paper, we will present nonlinear optical properties of wide-bandgap semiconductors, A1P, ion-implanted GaP and SiC, characterized by the reflected second-harmonic techniques.