On the theory of reflectivity and transmissivity of a lossless nonlinear dielectric slab

For the transverse electric polarization case (TE) we present a treatment of the optical reflectivity and transmissivity of a slab whose dielectric coefficient is a real valued function of the light intensity. If this function is numerically integrable with respect to the light intensity, our treatment can serve as an algorithm for a numerical solution of the nonlinear wave equation. If the dielectric function is proportional to the intensity, an analytical solution of the cubic wave equation is given for the electric field strength and for the phase of the field in terms of Weierstrass' elliptic functions and first elliptic theta functions, respectively. Evaluating this solution by means of a computer algebra system yields the reflectivity, transmissivity and phase dependency on the incident field intensity and on parameters characteristic for the problem. Certain combinations of the parameters lead to bistable and multivalued behavior. The solution found is used to determine the relative extrema of the reflectivity and the critical values of the thickness and of the incident intensity. The results are a generalization of linear optics results. Application of the analysis to the cubic-quintic wave equation yields the general analytic solution which is used to detemine the reflectivity of a semi-infinite nonlinear medium.     

TM-polarized nonlinear waves guided by asymmetric dielectric layered structures

We found the field structure, exact dispersion relations and power flow ofp-polarized nonlinear guided and surface waves travelling along a three-component layered structure consisting of a film of thicknessd with dielectric constant _b bounded at the negativez-side by a linear medium with dielectric constant _a and at the positivez-side by a nonlinear uniaxial substrate characterized by the diagonal dielectric tensor ₁₁ = ₂₂ = + (|E ₁|² + |E ₂|²), ₃₃ = , <0 (self-defocusing medium),E ₁ andE ₂ being the components of the electric field in thex andy-direction, respectively. It is shown that for sufficiently smalld/ (: wavelength) the nonlinear wave may exist only at power flows exceeding some certain minimum values. For sufficiently larged/ to some values of the power flow there correspond two distinct values of the propagation constant. In this case with increasing of the power flow the number of waveguide modes is decreasing and for higher-order modes the film-waveguide exhibits an optical-power limiter from the above behaviour.     

Surface nonlinear optics: a historical overview

The availability of widely tunable dye lasers and optical parametric oscillators permit the detection of surface specific electronic and vibrational states. Polarization dependent studies yield information about the orientation of molecular monolayers and surface specific bonds. The use of picosecond and femtosecond pulse–probe techniques permits time-resolved studies of surface phase transformations, desorption, and melting. A few examples from the rapidly growing literature are selected to illustrate this historical evolution. Received: 20 September 1998     

Theory of singular vortex solutions of the nonlinear Schrödinger equation

We present a systematic study of singular vortex solutions of the critical and supercritical two-dimensional nonlinear Schrödinger equation. In particular, we study the critical power for collapse and the asymptotic blowup profile of singular vortices.     

Influence of thermal treatment on second-harmonic generation in silver islands films

A reduction in second-harmonic generation (SHG) efficiency at silver islands films is observed when such submicroscopic structures are tempered at approx. 410K. This behavior can be attributed to two facts: an increase in symmetry in film morphology and changes in the particles' electron plasma resonances causing field enhancements inside the particles. The observed correspondence between submicroscopic surface morphology and obtained second-harmonic signal suggests a SHG microscope for the maplike distinguishing between differently structured surface areas.Dedicated to Prof. Dr. Herbert Welling on the occasion of his 60th birthday     

三层非线性平面光波导TM波的精确色散关系

对于介质薄膜波导的一边或两边复盖有介电常数与光强成正比的非线性介质的三种不同结构，本文导出了三层非线性平面光波导ＴＭ波的精确色散关系。对称三层非线性平面光波导的数值计算实例与有限元法的结果完全一致。     

Calculations of TM-polarized nonlinear waves guided by thin dielectric films

We found the dispersion relations for TM-polarized nonlinear waves guided by a dielectric film of thicknessd bounded on one side by a nonlinear uniaxial medium characterized by a dielectric tensor _xx = _y = _c , _zz = _c + _c |E _z |², _c >0 (self-focusing medium),E _z being the electric-field component perpendicular to the surfaces. Numerical calculations are given for the power dependence of the propagation wave vector. For sufficiently larged/ (: wavelength) we have found regions with multiple solutions corresponding to the same power flow. This suggests possible applications to optical devices.     

Photoconductivity in a photocrosslinkable second-order nonlinear optical polymer

Photoconductivity measurements on a stable photocrosslinkable nonlinear optical polymer — PVCN (polyvinylcinnamate)/CNNB-R (3-cinnamoyloxy-4-[4-N,N-diethylamino)-2-cinnamoyloxy phenylazo] nitrobenzene) are reported. Photoconductivity in this polymer system, in both crosslinked and uncrosslinked states, was observed without introducing any sensitizer or carrier-transport agents. Absorption of CNNB-R (_peak=518 nm) results in photocarrier generation and it is conjectured that CNNB-R also plays a role in the carrier transport. Such polymers are candidate materials for photorefraction.     

Polarisation control of light by light in a nonlinear polymer

Received: 11 December 1997/Revised version: 11 May 1998     

Transient conical parametric scattering of two orthogonally polarized waves in BaTiO3

The strength of the transient parametric scattering in BaTiO₃ is shown to be strongly dependent on the initial conditions of the sample illumination. It is shown that the effect can be explained by a considerable increase of the seeding radiation intensity after pre-exposure of the sample to the ordinarily polarized pump beam. Received: 27 March 2000 / Published online: 16 June 2000     

Nonlinear waves guided by a dielectric slab

An exact solution of Maxwell's equations is found for TM-polarized nonlinear guided waves which are guided by a linear dielectric slab embedded between two nonlinear uniaxial media. Additional waves in comparison with the linear case arise. Some of these waves have no counterpart in linear systems. Similarities and differences with respect to TE-polarized nonlinear guided waves are pointed out.     

Nonlinear waves guided by a dielectric slab

We consider dispersion relations and field structure of TE-polarized guided waves travelling along an asymmetric dielectric slab surrounded by two different nonlinear media. For a given configuration there are four types of guided waves. Three of this four types possess at least one field maximum outside the slab region and have no counterpart in linear waveguide optics. The solutions of the dispersion relations depend now on an additional parameter making them more flexible with respect to the linear limit.     

Wavefront study in a Gaussian beam passed through a nonlinear optical medium

We present a numerical model to study the wavefront of a Gaussian laser beam propagated through a nonlinear Kerr media. The model is based on the Gaussian decomposition method. The interaction between a laser beam and a self-focusing or self-defocusing media is discussed from the viewpoint of wavefront distortion. The method is useful for simulation of the wavefront of the beam next to the sample. We also compare our results with those obtained from z-scan method. There is a quite good agreement between data from z-scan method and our results.     

Stochastic processes in a nonlinear Kerr-like ordered liquid

A special case of the problem determined by laser-induced instabilities (at cw input) in wave interactions with inhomogeneous anisotropic media with high threshold nonlinearity under condition of energy competition and exchange between waves with orthogonal polarizations is examined.     

Method for measurements of second-order nonlinear optical coefficient based on Z-scan

The method for measuring second-order nonlinear optical coefficients based on well-known Z-scan is presented. The influence of linear absorption coefficients on normalized transmittance is discussed. Using this method, we obtained the second-order nonlinear coefficient d₃₁(5%MgO:LiNbO₃) = 4.5 × 10⁻¹² m/v at 1064 nm, which agrees well with theoretical calculations and previous well-known values.     

Optical phase conjugation and related experiments with surface plasma waves

We report on the experimental observation of optical phase conjugation using surface plasma waves in two different configurations: one involving four surface plasma waves and the other one involving two surface pump waves and bulk probe and conjugate waves. The major nonlinear contribution comes from heating of the metal film. In a related experiment, we have also observed the coupling of a bulk probe wave to the corresponding surface wave through the grating created by two counter-propagating surface plasma waves. In this case, we could observe the creation of surface acoustical waves.     

Second-harmonic generated by self-squeezed light in isotropic medium. The role of light intensity-dependent effects and molecular-statistical structure

An isotropic medium with electrically removed centre of symmetry in which a fundamental wave at frequency generates the second harmonic at 2 is considered. The two waves give rise to self-acting effects modifying the refractive indices at and/or 2 (selfinduced ellipse rotation, optical Kerr effect). For this physical situation, an effective interaction Hamiltonian is introduced involving nonlinear coupling parameters, discussed versus the dc electric field and temperature as well as the density, concentration and molecular structure of the medium. The solutions of the respective quantum equations for the field operators at and 2 permit, in particular, the calculation of the variances for a novel process of second-harmonic generation by light, self-squeezed in an isotropic medium. It is shown that squeezing in the out-of-phase component of the second harmonic beam follows, with some delay, after self-squeezing in the in-phase component of the fundamental beam.Sponsored by the Polish Academy of Sciences, Project CPBP 01.12     

Sum-frequency vibrational spectroscopy of a monolayer self-assembled on gold: interference between resonant and nonresonant contributions of nonlinear polarization

zzz ^(R) is dominant in the observed resonant signals, whereas all of the ijk components contribute to the nonresonant signal. The transition frequencies and the relative amplitude of resonant signals are also determined for the CH₃ vibrational modes of ODT on gold. Received: 21 August 1998 / Revised version: 16 September 1998 / Published online: 24 February 1999     

Modeling of enhancement of nonlinearity in oxide and chalcogenide glasses by introduction of nanometals

In this Letter we extended T-matrix to calculate the nonlinear susceptibilities of a composite nonlinear host and guest medium, and then applied this model to calculate the nonlinear susceptibilities of oxide and chalcogenide glasses by introduction of nanometals. The results of the model is in good agreement with experimental ones.     

Linear and nonlinear optical properties of a hydrogenic donor in lens-shaped quantum dots

Optical transitions in a Lens-Shaped Quantum Dot (LSD) are investigated in the presence of a hydrogenic impurity. The electronic wave functions are obtained analytically and the energy eigenvalues are calculated numerically. The density matrix formulation with the intersubband relaxation are used to evaluate the (linear and third order nonlinear) absorption coefficient (AC) and the change in the refractive indices (RI) analytically. The effect of the size of the LSD and optical intensity on the AC and RI are investigated. It is found that AC and RI are strongly affected by the optical intensity and the size of the LSD.