bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of molecular optical Hyperpolarisabilities using Hyper-Rayleigh Scattering
Authors: Verbiest T. , Hendrickx E. , Persoons A. , Clays K.
Published: February 2023

In this paper we report on new experiments of Hyper-Rayleigh Scattering (HRS) in solution, i.e. incoherent second harmonic light scattered from solutions illuminated by intense (IR) laser pulses. The HRS-technique, developed recently1, allows an accurate and easy determination of first order hyperpolarisabilities β of molecules. The great advantage of HRS as compared to electric field induced second harmonic generation (EFISHG, the other technique to determine β) is the absence of an orienting electric field to reduce the intrinsic symmetry of an isotropic solution. As a consequence data on the dipole moments are not needed and local field correction factors are unnecessary. HRS allows the determination of β of ionic species and will be the method of choice for the investigation of apolar molecules where p originates from octopolar charge distributions.2
Absolute Measurements of Second-Harmonic Generation Coefficients Using a Laser Diode
Authors: Kondo Takashi , Shoji Ichiro , Yashiki Kenichiro , Ito Ryoichi
Published: February 2023

There is a large discrepancy in currently accepted absolute values of second-harmonic generation (SHG) coefficients [1]. The discrepancy indicates that careful and accurate measurements using well-characterized laser sources are needed. Recently, Eckardt et al. performed measurements of absolute magnitudes of the phase-matchable nonlinear coefficients of several crystals using a pulsed Nd:YAG laser and pointed out that part of absolute values accepted as standards to date are erroneous [2]. In this paper, we report the accurate measurements of absolute SHG coefficients of lithium niobate (LiNbO3) using a high-quality semiconductor laser diode as a fundamental light source. This includes the first absolute measurement of the non-phase-matchable coefficient, d33, of this material. d33, the largest coefficient of LiNbO3, is an important parameter which determines performance of waveguiding frequency conversion devices.
Enhancement of the Nonlinear Optical Susceptibility of Optical Materials through Local Field Corrections
Authors: Boyd Robert W. , Bieber Amy , Gaeta Alexander L. , Maki Jeffery J. , Sipe John E.
Published: February 2023

There is currently great interest in the development of new nonlinear optical materials in which the nonlinear susceptibility is enhanced as the result of local field effects. In this contribution, we review the results of our theoretical and experimental investigations of the role of local field effects in enhancing the nonlinear susceptibility of optical materials.
Large Second-Order Nonlinearity in Bulk and Thin-Film SiO2
Authors: Myers R. A. , Mukherjee N. , Brueck S. R. J.
Published: February 2023

We have previously reported1 the observation of a large second-order nonlinearity in the near surface region of commercially available fused SiO2 windows induced by a combined temperature (200-325°C) and electric field (~ 30 kV/cm) preparation process. This preparation process includes heating the sample, in laboratory atmosphere, while applying a DC bias of 3-5 kV across the ~1.6 mm-thick samples with electrodes that are simply physically contacted to the sample. After several minutes at temperature, the sample is allowed to cool to room temperature with the bias field maintained. Following cooling, the bias field and the electrodes are removed and a permanent second-order nonlinearity is observed. This nonlinearity is monitored by second-harmonic generation, in transmission, using a Q-switched YAG laser source at 1.06 pm focused to an intensity of ~ 10MW/cm2.
Optical Second Harmonic and Sum-Frequency Studies of C60 Film
Authors: Stanners C. D. , Wilk D. E. , Chin R. P. , Shen Y.-R.
Published: February 2023

Recently there has been much interest in the physical and chemical properties of C60, motivated by exciting possibilities for the synthesis of novel materials. Here we report measurements of optical second harmonic (SHG) and infrared-visible sum-frequency generation (SFG) from C60 films. While second harmonic generation from C60 films has been previously observed1, no attempt has yet been made to identify the relevant second order nonlinear susceptibility elements. We have also investigated the adsorption of atomic hydrogen on the surface of films of C60 using SHG and SFG. The reactivity of the surface of C60 films is of importance for the fabrication and stability of new fullerene based materials.
Pulsed Nd-Lasers with phase-conjugating SBS-mirrors
Authors: Eichler H.J. , Menzel R. , Schumann D.
Published: February 2023

The beam quality of solid state lasers with high average power is limited by the wave front distortions caused by the active material. Thermal lensing and birefringence of the laser rods at high pump powers are the most disturbing effects. Consequently, the repetition rate of high power pulsed laser systems and the pump power cannot be varied in a wide range without changing the transversal mode structure or even the whole configuration of the system.
Phase conjugation at 10.6 μm via intersubband third order nonlinearities in multi quantum well structures
Authors: Gravé Ilan , Segev Mordechai , Yariv Amnon
Published: February 2023

The study of nonlinear optical effects in semiconductor multi quantum well (MQW) subbands and the related applications is a subject of current interest. Greatly enhanced second order nonlinearities, as compared to those in bulk materials, have been observed by different groups. Recently third order nonlinear effects were probed: via the DC Kerr effect(1), where very large enhancement ratios over bulk values were observed, and using a four wave mixing scheme(2) to measure a large χ(3), all in GaAs/AlGaAs superlattices.
Time-Multiplexed One-Way Imaging for High Spatial Frequency Aberration Correction
Authors: Chakmakjian Stephen H. , Gruneisen Mark T. , Kramer Mark A. , Esch Victor C. , Koch Karl
Published: February 2023

One way image compensation has been applied to aberration correction in such scenarios as static aberrations located between objects and collection optics,1 and aberrations situated within the imaging optics themselves.2 Real-time one-way image compensation has also been applied to image transmission through dynamic turbulent boundary layers.3 In each of these cases a corrective grating is created such that an image bearing beam diffracted off of this grating is corrected by virtue of the phase subtraction process characteristic of the minus one diffracted order. A primary limitations in these systems is the inability to correct for high spatial frequency aberrations. However, high spatial frequency compensation seems possible. Phase conjugation has been employed in double-pass correction methods to reverse an aberrated wavefront after it has traversed a multimode optical fiber.4,5 In this case the modal dispersion experienced in the fiber imposed an extremely high spatial frequency aberration rendering the image unrecognizable. In this paper we report a one-way imaging scheme capable of correcting such high spatial frequency aberrators as ground glass and multimode optical fibers. This is the first demonstration to our knowledge of one-way image correction with such a severe aberrator.
Dynamics of transient multiwave mixing-mediated effects-theory and experiment with liquid crystals
Authors: Khoo I. C. , Zhou Ping , Yu Liang , Li Hong , Lindquist R. G. , LoPresti P.
Published: February 2023

In this paper, we present a quantitative theory and experimental studies of the detailed dynamics of transient optical wave mixing processes.1,2 In particular, we have analyzed and explicitly obtained the time dependencies of all the interacting waves (our model is for four waves as shown in figure 1). Our theory takes into account diffusive mechanisms that characterize many nonlinear optical processes (e.g., carrier diffusion, thermal diffusion, intermolecular correlations, etc.).
Picosecond Nonlinear Optics of and Stimulated Emission from n- and p-type MBE ZnSe
Authors: Wherrett B.S. , Bolger J. , Kar A.K. , Galbraith I. , Wang S.Y. , Simpson J. , Prior K.A. , Cavenett B.C.
Published: February 2023

An explosion of interest in ZnSe based optoelectronic devices has followed the reports of diode laser action associated with this material [1,2]. We have, over a period of years, been investigating the nonlinear optical properties of bulk and thin-film ZnSe, initially with concern for all-optical switches and logic elements employing either optothermal or optoelectronic mechanisms. Degenerate-four-wave-mixing, nonlinear Fabry-Perot and z-scan techniques have been employed to measure the absorption cross-sections and induced refractive indices at cw, nanosecond and subpicosecond timescales, with particular concern for near-gap enhancements [3-6].
Ultrashort pulse generation by internal pulse compression of synchronously pumped optical parametric oscillators at degeneracy
Authors: Nebel A. , Beigang R.
Published: February 2023

Synchronously pumped cw mode locked optical parametric oscillators (OPO) are ideal sources for tunable ultrashort pulses in the visible and near infrared spectral region. They can be tuned over a wide wavelength range and picosecond and sub-picosecond pulses have been obtained already with substantial average and peak powers [1,2].
Dynamics of composite grating in photorefractive SBN:60
Authors: Sasaki H. , Ma J. , Fainman Y. , Lee S. H.
Published: February 2023

Dynamic photorefractive memories that store image information multiplexed in a photorefractive volume are promising for parallel information processing and computing due to their large storage capacity, fast access, and read/write/erase capability1. Incoherent erasure process can be used for updating these dynamic memories, but this process is much slower than the writing process. In contrast, selective erasure process2 based on superimposed recording of a π-phase-shifted image onto the old image is reported to be much faster than the incoherent erasure3. Arbitrary phase shift has also been investigated for optical interconnects4, assuming a grating with maximum refractive index modulation at the beginning of the selective erasure process. For dynamic photorefractive memory application it is important to understand the dynamics of the selective erasure process for multiplexed images, where each of them is characterized by a much smaller refractive index modulation. Dynamic photorefractive memory that uses π-phase-shifted selective erasure process has recently been implemented, demonstrating fast erasure capability5. In this manuscript, we analyze and confirm experimentally the dynamics of the erasure process. For simplicity and generality we assume two gratings with an arbitrary phase shift between them to be a composite grating, one being the old grating and another the new grating.
Polarization Properties of an Operational Photorefractive BSO Correlator.
Authors: Petersen P.M. , Buchhave P. , Andersen P.E.
Published: February 2023

In this paper we report on the polarization properties of a BSO autocorrelator used for fast transparency analysis in particle image velocimetry(PIV). The autocorrelator is an optical parallel dataprocessing unit that estimate the velocity distribution of a particle flow. The correlator uses the two beam coupling configuration shown in Fig. 1(a). The input to the optical processor is the PIV-transparency that is a double exposure photograph of the particle flow. The output of the processor is the autocorrelation function which consists of two side peaks and a central spot. The distance between the peaks and their relative orientation determine the velocity and the direction of the flow. In this work we compare the exprimental results from the autocorrelator with an analytical theory from a coupled-wave theory.
Photorefractive four wave mixing and photorefractive circuits
Authors: Wang S.L. , Pan H.F.
Published: February 2023

Degenerate four wave mixing in photorefractive media(PFWM) has been intensively studied theoretically. A complete solution of the coupled wave equation is steel not available. This makes some problems such as the uncertainty of the solution, lack of understanding of phase dependence and energy flux, and unable to treat those of multi coupled interaction regions. This paper is to give a general solution so that the PFWM can be described as a phase sensitive eight pin element arid apply it to various PFWM circuits by composing the elements for different uses.
Dynamics of Reverse Saturable Absorption in Phthalocyanines
Authors: Li Chunfei , Wang Hui
Published: February 2023

Saturable absorption (SA) in organometallic compounds, such as phthalocyanine (Pc), was extensively studied in 1960’s, the purpose of the research was to find suitable dyes to compress laser pulse. As we know, SA is due to the absorption of the ground state, which can be described by a two-level model or a three-level model[1]. At that time, the excited state absorption, only considered as residual absorption, had not received much attention.
Fabrication of Buried Channel Organic Nonlinear Waveguides
Authors: Isoshima T. , Ishikawa A. , Kanazawa A. , Hirayama H. , Tada K.
Published: February 2023

Nonlinear optics has been attracting a lot of attention, but currently obtainable degree of non linearity is not sufficient for many of the applications. In order to establish large optical nonlinearity, it is necessary to use a material with a large optical nonlinearity in a waveguide which can confine light strongly to inclease optical power density. For this purpose the channel waveguide is the most suitable because of its high optical confinement as well as its compatibility with optical integrated circuits. Among various nonlinear optical materials, low-molecular-weight organic materials such as 2-methyl-4-nitroaniline(MNA) are of great interest owing to their very large optical nonlinearity. However, they have disadvantages of low mechanical strength and low processability, and therefore it is not easy to fabricate channel waveguides with them. A few methods to fabricate organic crystal channel waveguides have been reported[1-3], but these methods have disadvantages such as difficulties in controlling the thickness or size of the core.
A Critical Phenomenon-Based Optical Bistability in Vanadium Dioxide
Authors: Rana R. S. , Nolte D. D. , Chudnovskii F. A.
Published: February 2023

The characteristics of nonlinear thin film etalons and interference filters are being studied because of their potential use as optical logical elements1. Low-power optical bistability in thin film nonlinear interference filters has been demonstrated at room temperature using zinc sulphide (ZnS) and zinc selenide2 (ZnSe). These bistable devices rely on electronic nonlinearities to operate. A switching power of 5 mW and switching speeds of 1 ms - 10 μs are typical for these devices.
Periodic Behavior in Photorefractive Two Beam Coupling
Authors: Statman David , Gass Karl , Liby Bruce W.
Published: February 2023

It is well known that the behavior of dynamical processes described by non-linear equations may lead to period doubling bifurcations and quasi-periodic behavior. Krolikowski, et.al. (1) have predicted that for four wave mixing, in the presence of an applied external field, periodic behavior can be observed. These predictions show that the observed period is constant in time for a given set of parameters. We have completed two beam coupling experiments using a helium neon laser as a source, and barium titanate as the photorefractive material. In the absense of an applied electric field we have observed periodic behavior during these experiments.
Subpicosecond time resolved four-wave mixing spectroscopy in heteroepitaxial ZnSe thin layers
Authors: Takeuchi K. , Saiki T. , Kuwata-Gonokami M.
Published: February 2023

The successful demonstration of laser oscillation using ZnSe based materials [1] makes it more realistic to expand the optoelectronics into the blue region. To construct the optoelectronics system in blue region, we need efficient nonlinear materials which can work in this wavelength. Recently, we observed a very large third order optical nonlinearity at the exciton resonance in ZnSe films [2]. Ema et al. demonstrated all optical serial to parallel conversion up to sub-Tbit/sec using this material [3]. Thus the ZnSe based materials are strong candidates for the nonlinear optical devices in blue region. To know the dynamics of excitons is essential to examine the applicability of the materials to ultrafast optical devices. In this report, we discuss the dynamics and enhanced nonlinearity of excitons in heteroepitaxial ZnSe thin layers by picosecond and femtosecond time resolved four-wave mixing spectroscopy.
A novel approach to all-optical switching based on second-order nonlinearities
Authors: Assanto Gaetano , Stegeman George I. , Sheik-Bahae Mansoor , VanStryland Eric
Published: February 2023

Materials with large and fast third-order nonlinearities and low losses have proven difficult to find and use in all-optical switching device configurations. Large nonlinear phase shifts, however, can be obtained in non-centrosymmetric materials relying on a cascaded second-order effect, i.e. up-conversion of a fundamental beam into its second-harmonic and the subsequent down-conversion for a phase-mismatched interaction.[1-2] Because of the recent development of efficient second harmonic generation in waveguides, it appears that phase shifts of order π can be reached over centimeter distances with peak powers of 10's of Watts or less in KTP or poled polymers, an improvement of orders of magnitude over the current capabilities of third order materials.
Energy Scaling of SBS Phase Conjugate Mirrors to 4J
Authors: Mangir Metin S. , Rockwell David A.
Published: February 2023

Phase conjugation (PC) via stimulated Brillouin scattering (SBS) is widely used, convenient technique for improving the performance of many pulsed lasers. For laser output energies ~1J, satisfactory performance can generally be achieved using a simple SBS phase-conjugate mirror (PCM) in which the beam to be conjugated is simply focussed into a bulk SBS medium. Exploitating PC in lasers producing output energies >10J requires a PCM that produces good conjugation fidelity at energies >1J.
Second Harmonic Generation in an Optically Active Liquid: Experimental Observation of a Fourth-Order Optical Nonlinearity Due to Molecular Chirality
Authors: Dubrovskii A.V. , Koroteev N.I. , Shkurinov A.P.
Published: February 2023

Molecular left-right asymmetry is an origin of non-vanishing even order optical nonlinear susceptibilities of non-racemic solutions of chiral molecules. Though second harmonic generation (SHG) due to quadratic dipolar nonlinearity is still symmetry forbidden in optically active liquids yet we have succeeded in experimental observation, for the first time, of noncolli-near SHG due to five-mixing process according to a scheme 2ω=3ω−ω, governed by a fourth order susceptibility tensor χ(4)D(2ω;ω,ω,ω,−ω) SH signal is found to be well collimated and quasi phase-matched, it shows theoretically predicted polarization, spectral and temporal properties.
Optical Image Recognition System Implemented with a 3-D Memory Disk
Authors: Psaltis Demetri , Li Hsin-Yu , Qiao Yong , Curtis Kevin
Published: February 2023

Holographic storage of data in 3-D media can provide high density of information storage and parallel access to the stored information. Such memories were investigated extensively in the early 60’s [1,2,3,4,5] and even though these early efforts produced remarkable results they never found practical application largely because of material limitations such as low sensitivity, fanning, and hologram decay. Interest in holographic 3-D memories has been revitalized in recent years for a variety of reasons, the most significant probably being the emergence of applications, such as neural networks, machine vision, and databases, that can make use of the capabilities of holographic 3-D memories.
Self-induced-transparency in an Erbium-doped Fiber
Authors: Chi Sien , Wang Tsun-Yee , Wen Senfar
Published: February 2023

The self-induced-transparency (SIT) is a phenomenon of a coherent pulse propagating in a resonant medium without loss and distortion when the pulse energy exceeds a critical value. [1] Since the recent development of the erbium-doped fiber amplifiers, it is interesting to consider the SIT in the silica-based erbium-doped fiber (EDF).[2] It is known that there exist nonlinear Schroedinger (NLS) solitons in the fiber due to the combined effect of the Kerr effect and the negative dispersion. Therefore, the coexistence of a SIT soliton and a NLS soliton has been a subject of intense interest. In Ref.[2], it is shown that impractical large dispersion is required for the SIT-NLS soliton to exist in EDF. In this talk, we extend our previous work [3] on the theory of the SIT-NLS soliton without making the slowly varying envelope approximation (SVEA) and show that it is practical for the SIT-NLS soliton to exist in EDF because the effect of the SIT induces large negative dispersion.
Holographic Recording in Algal Solutions
Authors: Brown K M , Lamb K , Ruddock I S , Cunningham A , Illingworth R
Published: February 2023

Crystals such as Barium Titanate and Bismuth Silicon Oxide can record holograms in the form of phase gratings by their photorefractive response to an interference pattern. Absorption of light in a photorefractive crystal generates electric charges which due to trapping in the dark regions effectively diffuse from the anti-nodes to the nodes of the interference pattern. The charge separation produces a local electric field which in turn modifies the refractive index by the Pockels effect thus yielding a phase grating [1,2]. Algae, which exhibit photo-induced taxis, the movement towards or away from a light stimulus [3], may be thought of as behaving in an analogous manner except that by their presence or absence they change the local transmission of a sample instead of its refractive index. In phototaxis, cells respond to non-uniform illumination by sensing the light intensity, whereas in chemotaxis, the cells migrate along an oxygen gradient due to photosynthesis caused by the non-uniform illumination. The investigation of taxis in biological cells has a long history, the term phototaxis first being used in 1878 [4], but most observations have concerned the dynamics and characteristics of the phenomenon as manifested for particular species. We report here for the first time, the temporal and intensity dependence of the optical density and the recording of an optical interference pattern in a suspension of the flagelette Dunaliella Primolacta.
Nonlinear Optics with Ultracold Cesium Atoms
Authors: Verkerk P. , Lounis B. , Boyd R. W. , Salomon C. , Grynberg G.
Published: February 2023

Recently, great progress has been made in the cooling and trapping of atoms. It is now possible to create a collection of atoms with a number density in excess of 1011cm-3 and a kinetic temperature of the order of 10 μK. At such low temperatures the mean atomic velocity is of the order of 10cm/sec and the resulting Doppler width of the atomic transition is much lower than the homogeneous width. Furthermore, it has been shown that a substantial fraction of the atoms are localized inside wavelength-scale potential wells due to light-shifts[1]. Such a collection of essentially stationary atoms provide a reasonably large nonlinear susceptibility that can be exploited for the study of various nonlinear optical interactions [2].
Resonant Multiphoton Electron Emission and Stark-Tuned Third Harmonic Generation in Coupled Quantum Wells
Authors: Sirtori Carlo , Capasso Federico , Sivco Deborah L. , Cho Alfred Y.
Published: February 2023

Asymmetric quantum well (QW) structures have recently attracted considerable attention as nonlinear optical materials with intersubband nonlinear susceptibilities in the ir (λ~10 μm)1–3 many orders of magnitude higher than in bulk semiconductors.1–3 In this paper we report the observation of a new nonlinear optical phenomenon: resonant multiphoton electron emission from a QW. This effect is conceptually similar to multiphoton ionization of a molecule, although its cross section is much larger. Our AlInAs/GaInAs sample (40 periods of a coupled-well-structure consisting of 42 Å, 20 Å and 18 Å GaInAs wells, separated by 16 Å AlInAs barriers, with only the thickest well n+ doped) is designed to have nearly equally spaced bound states (≃120 meV). By appropriately choosing the photon energy and Stark shifting the energy levels electrons can be ejected out of the well via a 3-photon transition into continuum states. For the experiments a linearly polarized CO2 laser is used and the structure is processed in a two-pass 45° waveguide. The laser is initially polarized so as to maximize the component normal to the layers; the polarization is then rotated or the power is varied. The measured photocurrent at 30 K scales as

P
0
3

sin

6

θ

, where P0 is the laser power and θ the polarization angle, giving direct evidence of 3-photon electron emission from the well. The photocurrent as a function of photon energy shows a strong peak which arises from the resonant enhancement of the transition rate by the second and third energy levels. From our data the 3-photon emission cross section is estimated. In another experiment third harmonic generation is studied as a function of electric field (magnitude and polarity) at a pump photon energy ≈ 118 meV. Two peaks are observed. The one at zero bias arises from a triple resonance of the pump photons with the three bound excited states of the QW. The second one is caused by the strong Stark shift of the energy levels and arises from a triple resonance with the first two bound excited states and the first resonant state in the classical continuum above the barriers. The measured peak nonlinear susceptibility

χ

3
ω

(
3
)

is

≃
3.5
×

10

−
14

(
 
m
/
V
)

2

≃

three times the value previously measured3 at 300 K and the highest ever reported in any material.
Time-Domain Spectroscopy with Fsec Pulses of THz Radiation
Authors: Grischkowsky D.
Published: February 2023

This paper will first describe the optoelectronic generation and detection of freely-propagating fsec pulses of THz electromagnetic radiation, and then applications of the optoelectronic THz beam system to THz time-domain spectroscopy (TDS) will be presented. Via optoelectronic excitation, a transient point source of THz radiation is generated at the focus of a dielectric collimating lens, followed by an additional paraboloidal focusing and collimating mirror. This source produces well collimated beams of fsec pulses of THz radiation. Matched to an identical receiver, the resulting system has extremely high collection efficiency (1). With a demonstrated signal-to-noise ratio of 1000, a time resolution of less than 150 fsec and a frequency range from 0.2 THz to more than 5 THz, the performance of this optoelectronic THz system is limited by the intrinsic response time of the semiconductor (2).
Static and Dynamic Optical Bistability in Fabry-Pérot and Distributed Feedback Resonators with Quantum Well structures
Authors: Castelli F. , Lugiato L.A. , Bava G.P. , Debernardi P.
Published: February 2023

Recently relevant results on optical bistability in Multiple Quantum Well (MQW) structures at room temperature have been reported [1].
Extra Resonances in Time-Domain Nonlinear Spectroscopies
Authors: Fourkas John T. , Trebino Rick , Fayer M. D. , Dugan Mark A.
Published: February 2023

Extra resonances between initially unpopulated excited states (IUES) or equally populated ground states (EPGS) have been studied extensively in the context of frequency-domain nonlinear spectroscopies such as Nearly-Degenerate Four-Wave Mixing (NDFWM)1. In the absence of strong laser fields2 or effects such as pure dephasing3, stochastic fluctuations in laser fields4, and laser transients5, the NDFWM extra resonances are either very weak (in the case of EPGS) or nonexistent (in the case of IUES). It is perhaps under-appreciated that "Fourier-transform" time- and frequency-domain FWM techniques do not necessarily provide the same information. For instance, under certain circumstances6, the NDFWM and transient grating (TG) techniques form such a pair, which would imply that TG extra resonances might disappear under the same experimental conditions in which they disappear in NDFWM. This assumption is belied by the TG data shown in Fig. 1. These data were taken by exciting and probing the D1 line of Na atoms in a cell in which there was no buffer gas and the Na pressure was low enough to preclude any significant number Na-Na collisions on the experimental time scale. Even in the absence of pressure-induced dephasing, these data exhibit strong extra resonances at both the 1.77-GHz ground-state hyperfine-splitting frequency and the 189-MHz excited-state hyperfine-splitting frequency. These data have prompted us to undertake a theoretical study of the nature of extra resonances in time-domain nonlinear spectroscopies, the preliminary results of which are discussed here. We show that time-domain extra resonances increase in strength with decreasing dephasing, and that IUES resonances exist even in the complete absence of pure dephasing. Finally, we show that IUES and EPGS extra resonances have a common origin in the time domain.
Coherent Phase and Frequency Detection using Sum-Frequency Mixing in Nonlinear Waveguides
Authors: Janz S. , Frlan E. , Dai H. , Chatenoud F. , Normandin R.
Published: February 2023

When two counter-propagating guided modes interact in a nonlinear waveguide, sum-frequency (SF) light is radiated from the waveguide surface (1). Recently, a multilayer Al
x
Ga1
–x
Aswaveguide structure has been developed which has a SF generation efficiency several orders of magnitude larger than conventional homogeneous waveguides (2). As as a result, there is much interest in the application of SF generation in waveguides for various optoelectronic devices including spectrometers (3), correlators (4), and coherent visible light sources (5). In this paper, we demonstrate an optical phase and frequency detector based on SF mixing in a multilayer guide. The waveguide shown in Fig. 1 is pumped by two counter-propogating TE modes,

Es+

andE

s
−

, at the signal frequency w
s
, and two counter-propogating TM modes,

E
o
+

andE

o
−

at the reference frequency w
o
.
Frequency-domain interferometer for femtosecond time-resolved phase spectroscopy
Authors: Kobayashi T. , Tokunaga E. , Terasaki A.
Published: February 2023

In femtosecond absorption spectroscopy, by the pump-probe technique with a white-light continuum difference transmission spectra (DTS) can be obtained by a single-shot measurement in principle. On the other hand, in femtosecond phase spectroscopy, which should be complementary to femtosecond absorption spectroscopy, there have been no methods so far by which difference phase spectra (DPS) can be obtained by a single-shot measurement.
Time-Resolved Four-Wave Mixing in Optically Dense Medium
Authors: Belov M. N. , Selifanov M. A. , Manykin E. A.
Published: February 2023

Time-resolved four-wave mixing CTRFWMZ) is a powerful method to study dephasing processes in solids [1]. The self-diffraction or two-pulse scheme of this phenomenon is shown in Fig.1. Presently, a number of the experimental and theoretical works dealt with TRFWM is reported [2-8]. Recently, the novel results which demonstrate the anomalous response of TRFWM with a signal at negative time delays, were obtained [9-10]. This effect cannot be predicted on the basis of the traditional Bloch equation approach [2].
Kramers-Kronig relations with opposite signs observed by femtosecond frequency-domain interferometry
Authors: Tokunaga E. , Terasaki A. , Kobayashi T.
Published: February 2023

The Kramers-Kronig (K-K) relations1 connect the real and imaginary parts of the linear susceptibility χ(ω). It was also proved that the K-K relations can be extended to nonlinear optics as far as the causality condition is satisfied.2 In particular in steady-state pump-probe spectroscopy, the usual K-K relations hold to all orders in the pump field if the pump frequency is fixed. On the other hand, the applicability of the K-K relations in time-resolved spectroscopy is not obvious. It has been difficult so far to study the time-resolved dispersion relations because of the experimental difficulties in measuring time-resolved difference phase spectra (DPS).
The Influence of Second Order Optical Nonlinearity on Effects of the Nonlinear Index of Refraction
Authors: Schiek Roland
Published: February 2023

In recent years, efforts to exploit the third-order optical nonlinearity in devices for optical signal transmission (soliton propagation) and signal processing (nonlinear switching) have multiplied [1, 2, 3]. In contrast to the theoretical description of soliton propagation in optical fibers, the simulation of χ(3)-effects in integrated optic signal-processing components employing materials without inversion symmetry necessitates the consideration of the non-vanishing second-order nonlinear susceptibility χ(2). Here, the input optical field drives an, in general, phase-mismatched second harmonic (ω + ω → 2ω) which, in a further second-order mixing process with the input field (2ω – ω→ ω), generates a nonlinear polarization at the input field frequency. This nonlinear polarization, caused by two simultaneously occuring second-order mixing processes, combines with and modifies the effect of the directly generated third-order polarization.
Femtosecond Solitary Pulses in Solid State Lasers
Authors: Krausz F. , Brabec T. , Spielmann Ch. , Wintner E. , Schmidt A. J.
Published: February 2023

The third-order nonlinear optical susceptibility χ(3) accounts for a great variety of physical processes in nonlinear optics.1 For the generation and propagation of ultrashort optical pulses the intensity-dependent refractive index n =n0 + n2Iis of particular importance, where n2(ω) ~ χ(3)(ω,–ω,ω). If the frequency dependence of n2(ω) is negligible in a broad frequency region, i.e. the main contributions to χ(3) (ω,–ω,ω) are nonresonant, the change in the refractive index follows instantaneously the variation of the intensity of the electromagnetic radiation. Consequently, the carrier frequency and, in the case of free propagation (no waveguiding), the spatial intensity distribution of an intense light pulse are subject to ultrafast modulation (self-phase modulation and time-dependent self-focusing) when propagating through transparent optical media.
Fast Photorefractive Planar Gratings in Fe-LiNbO3 Crystal
Authors: He Q. Byron , Yeh Pochi , Hu L. J. , Yeh T. S. , Lin S. P. , Lin C. H. , Tu S. L. , Yang S. J. , Hsu Ken
Published: February 2023

Photorefractive crystals have been widely studied in recent years. The dynamic holographic nature, high-resolution, and energy coupling effect of photorefractive crystals make them especially useful in optical image processing, optical computing and optical interconnections [1]. Real-time optical image correlators have been demonstrated experimentally in a variety of photorefractive crystals [2, 3]. However, due to the angular selectivity of Bragg diffraction in volume gratings, shift invariance in these correlators is hardly achieved. In this paper, we present experimental studies of a thin photorefractive Fe-LiNbO3 crystal plate and report the first observation of planar gratings in the samples. Such planar gratings are useful in achieving shift-invariant real-time optical image correlators.
Progress in Tungsten Bronze Ferroelectrics For Photorefractive Applications
Authors: Neurgaonkar R. R. , Cory W. K. , Oliver J. R. , Sharp E. J. , Wood G. L. , Salamo G. J.
Published: February 2023

The potential of photorefractive materials for applications such as phase conjugation, image processing, laser hardening and optical computing has stimulated the development of new electro-optic materials. Currently, tungsten bronze (T.B.) ferroelectrics, as well as BaTiO3, KNbO3 and LiNbO3 are being seriously evaluated for these applications.
Enhanced Photorefractive Transient Response
Authors: Duree Galen C. , Shultz John L. , Bei Nianyu , Salamo Gregory J. , Sharp Edward J. , Wood Gary L. , Neurgaonkar Ratnakar R.
Published: February 2023

A physical model for the photorefractive effect consists of considering two laser beams which are allowed to cross in a photorefractive crystal, producing an interference pattern. This interference pattern, or alternating light and dark regions in the crystal, results in the selective excitation of free-carriers from impurity trapped sites in the illuminated regions into the conduction band. In the conduction band, there is a subsequent diffusion of these electrons to neighboring dark regions where they are re-trapped at empty impurity sites. This transport of charge develops a space-charge field which, at equilibrium, produces a restoring force that exactly balances the diffusive force experienced by the excited free-carriers.
Nonlinear Optics of Quantum Anti-Dots in Bulk GaAs
Authors: Nolte D. D. , Brubaker R. M. , Melloch M. R. , Woodall J. M. , Ralph S. J.
Published: February 2023

Nanometer-size arsenic clusters distributed throughout MBE-grown GaAs quantum-confine excitons exterior to their volume. We observe transport-assisted nonlinear optical mixing based on the electro-optic and transport properties of GaAs:As.
Broadband Quasi-Phase Matched Second Harmonic Generator using Taper Waveguide
Authors: Haga Hiroshi , Kameoka Makiko , Yamamoto Sadahiko
Published: February 2023

Quasi-phase matching (QPM)[1] offers many advantages such as no restriction imposed on material, use of the largest SHG tensor component and the fundamental guided modes for obtaining the largest field overlap, and so on. In practice, however, deviations in parameters, e.g., grating period, waveguide width, refractive indices, caused in fabrication process or in operating conditions, reduce the SHG efficiency. It is therefore very important to design SHG devices which are tolerable for fabrication errors and operating conditions. Theoretical analysis has shown that large tolerance can be obtained with chirped grating[2]. In this paper, we propose a simple structure for broadened phase matching and present results of basic theoretical analysis.
Accurate Finite Element Analysis of Nonlinear Optical Fibers
Authors: Rahman B.M.A. , Liu Y. , Buah P. A. , Grattan K.T.V. , Fernandez F.A. , Ettinger R.D. , Davies J.B.
Published: February 2023

Nonlinear optical effects in fibers such as optical solitons are closely related to the optical Kerr effect[1]. Calculations are presented here of propagation constants, field distributions and spot sizes, in step index and graded index optical fibers with Kerr- and saturation-type nonlinearities.
Switching Modes of a Nonlinear Waveguide
Authors: De Angelis C. , Nalesso G.F. , Someda C.G.
Published: February 2023

The asymmetrical slab nonlinear–waveguide (NLWG), extensively studied in recent years (e.g. [1]), is a good candidate to be used in all–optical–switching. In this paper we study (analytically and numerically) the dependence of the switching properties of the NLWG (see fig. 1) on "a" (half width of the waveguide) and “k0" (vacuum wavenumber). We show that it has two switching modes, whose physical nature and whose performances differ remarkably.
Characteristics of Optical Bistability in CdsxSe1-x Doped Glass with Channel Waveguide Structure
Authors: Xu Mai , Huo Zhenguang , An Ning , Peng Wenji , Yu Zhenxin
Published: February 2023

CdsxSe1-x doped glasses are a new and developing nonlinear optical material in the 1980s[1]. During to local field enhaned effect of small semiconductor crystallite particles in glass matrix, large optical-nonlinearity of CdsxSe1-x doped glass material have been shown. When ratio of surface to volume is increased by decreasing crystallite size, carrier recombination on the crystallite surfaces should be the dominant process. As a result, carrier recombination rate should be about pico-second[2].
Optical SHG in MgO:LiNbO3 Waveguides Using Phase Matching of Coupled Mode Dispersions for LD
Authors: Miyazaki Yasumitsu , Kudo Koichi
Published: February 2023

Making use of MgO:LiNbO3/LiTaO3, we experimented 0.83 μm-0.415μm SHG by optical waveguide-type SHG devices in which the phase-matching condition is satisfied by using mode dispersion of thin film. 13% conversion can be achieved when input power is 40 mW.

In the new coupled optical waveguide-type SHG device, which is proposed, the phase matching condition is satisfied by using coupled mode dispersion of coupled optical slab waveguide. According to the theoretical analysis, the coupled optical waveguide-type, the materials of the device have more feasibility. Further, the phase-matching can be done easily.
Pulse Evolution in Birefringent Fibers under the Influence of Four-Wave Mixing and Stimulated Raman Scattering
Authors: Schulz R. , Harde H.
Published: February 2023

The propagation of high power laser pulses through glass fibers is affected by nonlinear optical effects which can be described by the third order nonlinear susceptibility χ(3) = χ′(3)+ iχ″(3). The real part contains self- and cross-phase-modulation (SPM and XPM) causing spectral broadening, and it is responsible for the parametric four wave-mixing process (FWM) which leads to the generation of a Stokes/anti-Stokes wave pair and requires phase matching. The imaginary part describes Stokes frequency conversion due to stimulated Raman Scattering (SRS). This process is always self phase matched. Most of the research work published has treated the effects of SRS and FWM independently [1] even though they may act simultaneously [2]. A simultaneous treatment becomes necessary when the frequency shift at which phase matching occurs falls within the Raman amplification profile. In this paper we present experimental and theoretical results of the combined action of FWM and SRS in a birefringent fiber under the influence of SPM, XPM and group velocity dispersion.
Pumped-cavity frequency-doubling of semiconductor laser radiation
Authors: Tyler David W. , McInerney John G.
Published: February 2023

One demonstrated scheme for doubling AlGaAs and InGaAs laser radiation to the blue (.400-.500 pm) is pumped-cavity secondharmonic generation (PC-SHG) [1]. In this scheme, an optically nonlinear medium is placed in a cavity pumped by an external source. We show that optimization of this process is a nonlinear problem and have developed a simple algorithm for selection of optimal parameters.
All-optical, polarization-independent switching using the Sagnac interferometer
Authors: Avramopoulos H. , Whitaker N. A. , Gabriel M. C. , French P. M. W.
Published: February 2023

Polarization-dependent operation is a serious obstacle in the development of practical photonic devices. In photon-photon devices polarization dependence can arise from different reasons. For example, orthogonal linear polarizations are often used to isolate the two input channels of a three terminal device. In such a case polarization dependence is essential for proper operation of the circuit. Also, in devices where interferometry is used, the polarization of the signal and reference beams must be the same or the interference is incomplete. Schemes such as polarization diversity do not work with nonlinear optical devices, as the interaction is intensity dependent. One successful approach is active polarization control, which requires detection and control circuitry combined with a LiNbO3 electrooptic polarization controller [1]. Active control however, entails extra complexity and expense, and the difficulty involved leads one to the search for simpler schemes.
Study on Optical Parametric Oscillator Pumped by a Pulse with Gaussian Distribution in Time
Authors: Wang Diankui , Yao Jianquan
Published: February 2023

Recently the research and development of optical parametric oscillator (OPO) were great promoted because of the progress of optical materials and laser techniques. We reported the operating characteristics of temperature tuned OPO pumped by a pulse in MgO:LiNbO3 /1, 2/. Some experimental results could be explained by the solutions of the coupled wave equations with stable pump. New theoretical methods in studying pulse-pumped OPO were established by some scholars /3, 4/.
Many-Body Semiconductor Laser Theory: A comparison with Phenomenological Theories
Authors: Moloney J.V. , Ru P. , Indik R. , Koch S.W. , Wright E.
Published: February 2023

The space-time dynamical behaviour of multi-stripe index/gain guided semiconductor laser arrays and broad area lasers is studied using the coupled Maxwell Semiconductor Bloch equations which include transverse diffraction of the counterpropagating optical fields and many-body effects between the carriers in the active medium. Our results confirm that evanescently coupled multi-stripe and broad area lasers are a fascinating manifestation of spatio-temporal complexity in spatially extended nonlinear systems. Stabilization of the laser output can be achieved by injection-locking the array with a weak external injected signal. The broad area laser shows random intensity filamentation in free-running mode and can be stablized to produce high power output by using an unstable resonator configuration for transverse mode discrimination. A direct comparison is made with phenomenological theories and one of our main conclusions is that these theories can be salvaged in strongly index-guided multistripe structures by appealing to microscopic many-body semiconductor theory to provide the fundamental problem parameters. We note marked differences in predictions of both theories for gain guided structures.
Multiple Wavelength Ultraviolet Laser Source for Remote Spectroscopy by Multiple Nonlinear Conversion of a Nd:YAG Laser
Authors: Palombo K. V. , Mordaunt D. W. , Gregor E.
Published: February 2023

This paper describes the development of a multi-wavelength ultraviolet (UV) laser source suitable for remote spectroscopy and detection of organic compounds in the atmosphere. Such a laser source would be suitable for stand-off detection of biological or organic compounds by exciting fluorescence and then monitoring the returned energy in the fluorescence spectrum. Having multiple UV wavelengths or the ability to tune the UV laser output wavelength provides greater resolution and discrimination between compounds with similar fluorescence spectra.
Research of Self-thermal Effect in High Efficient Nd:MgO: LiNbO3CW Self-frequency-doubled Laser
Authors: Li Rui-ning , Wang Jun-min , Liang Xiao-yan , Xie Chang-de , Peng Kun-chi , Xu Guan-feng
Published: February 2023

The CW self-frequency-doubling in Nd:MgO:LiNbO3 crystal has been demonstration by T. Y. Fan et al[1]. They did not consider the influence of the self-thermal effect of the crystal irradiated by laser beam on itself temperature. We found that the external control temperature for the optimum phase-matching to generate the second-harmonic wave in Nd: MgO:LiNbO3 CW self-frequency-doubled Laser must be decreased as the input pump powers were increased. Because the pump irradiance absorbed by the crystal inevitablely resulted in the temperature rise, the external control temperrature forced on the crystal must correspondingly be decreased to maitain the optimum phase-matching temperature needed by the self-frequency-doubled process. The dependence of the control temperatures for the phase-matching on the absorbed pump powers was experimentally measured. We obtained up to the CW second-harmonic output power of 3 mW which was three times more than the previous obtained power level[1] with the Nd:MgO: LiNbO3 laser cavity pumped by CW Rhodamine 6G dye laser tuned to the 598nm absorption line of the material. The conversion efficiency, defined as the ratio of total second-harmonic output to pump power absorbed above threshold, was about 15% per watt which was twice of previous result[1].