This PDF file contains the front matter associated with SPIE Proceedings Volume 7993, including the Title Page, Copyright information, Table of Contents, and the Conference Committee listing.

Random quasi-phase-matched frequency doubling of fs pulses to the deep UV was obtained in 1D nonlinear photonic crystal (NPC) of strontium tetraborate. Tuning range of generated radiation is from 187.5 to 215 nm. The spectrum of generated radiation consists from series of peaks with the width of order of 1 Å. These peaks are the manifestation of the NPC band structure. Using fs oscillator as the fundamental radiation source, maximum average power of generated radiation is of order 1 μW, the enhancement factor with respect to monodomain sample being of order of several hundred. The red rotational shift of NPC band structure is experimentally demonstrated.

The nonlinear optical limiting and relative nonlinear refractive index in far-field of acid blue29 dye are investigated using radiation of 35mW CW He-Ne laser. It is found that both nonlinear refraction and nonlinear absorption change with decreasing of solvents polarity and varying the input powers.

Ultra fast pulse evolution in a semiconductor quantum well structure (QWS) is theoretically analyzed using split-step Fourier method. The induced polarization in the medium has been obtained using Semiconductor Bloch equations. The non-linear Schrödinger equation is numerically solved by taking into account the induced polarization. So far, the pulse shape studies are based on the group velocity dispersion (GVD), third-order dispersion (TOD) and self phase modulation (SPM) effects. However, at high excitation intensity the group velocity also becomes intensity dependent. In the present analysis, the interplay of GVD, TOD and SPM leading to the change in pulse shape is studied giving due consideration to the intensity dependent group velocity of the medium. The result of numerical analysis made for a GaAs/AlGaAs QWS manifests significant influence of intensity dependent group velocity on the pulse shape.

Spectral-luminesnce, nonlinear-optical and photochemical characteristics of metal complexes with new tetraphenylporphyrin (TPP) derivatives, with atom Lu(III) or Gd(III) in the ligand-complexone or as a central ion, in liquid and frozen solutions and in state-solid polymer matrices also are studied. The limiting coefficient (LC=T₀/T_W) at power density about 250 MW/cm² chosen as gauge of nonlinear-optical properties. Phototransformation quantum yield under 2nd harmonic of Nd-YAG-laser irradiation (φ₅₃₂) chosen as gauge of photostability. Results of investigation show significant nonlinearity of studied substances caused by reverse saturable absorption. Compounds photostability quite enough, spectral characteristics of irradiated samples are evidence of protonated nature of photoproduct, which in one's part make contribution to power radiation absorption.

Ultraviolet (UV) and vacuum-UV pulses (VUV) were simultaneously generated by using four-wave mixing through filamentation in neon gas. Second harmonic of Ti:sapphire laser output (400 nm, ω_SHG) and near infrared pulses (1200 nm, ω_NIR) from a noncollinear optical parametric amplifier were gently focused into neon gas, and ultrashort pulses with the center wavelengths of 237 nm (ω_fwm) and 167 nm (ω_cas) were produced by four-wave mixing processes ω_SHG + ω_SHG - ω_NIR → ω_fwm and ω_fwm + ω_SHG - ω_NIR → ω_cas, respectively. The energy of the generated 237 nm pulse was more than one micro joule. Transfer of spectral phase from the near infrared ultrashort pulses to the UV pulses through the four-wave mixing process was also demonstrated. The even order spectral phase of the near infrared pulse was transfered to the UV pulse with the opposite sign, whereas the odd order spectral phase was transfered with the same sign. A positively chirped near infrared pulse was used for generating a negatively chirped UV pulse, which was compressed down to 25 fs by a magnesium fluoride window. In principle, the spectral phase transfer scheme can also be applied to the chirp control of the generated VUV pulses.

Second-order NLO characteristics of thin films based on model epoxy amine oligomers with 4-amino-4'-nitroazobenzene chromophore in the main chain, containing hydroxyl and methacryloyl groups, CFAO and CFMAO, respectively, are determined. Synthesized polymers possess high content of chromophore fragments and have good film-forming properties, which allowed one to cast homogeneous films of 200-400 nm thickness. The presence of reactive groups in the monomer units makes it possible to use cross-linking of polymer matrix to preserve the chromophores orientation order achieved in the course of corona poling and to provide relaxation stability of the second-order NLO response. Rather high values of the nonlinear optical coefficients estimated by second harmonic generation technique allow one to consider these epoxy amine polymers as promising candidates for the construction of cross-linked polymer matrices with long-term stability of the quadratic NLO response at elevated temperatures.

The features of the reflection of quasi-monochromatic optical pulse from intensive low frequency few cycle pulse in various nonlinear media are analyzed. The reflection effects are studied for the interaction of the optical pulse with low frequency solitons and breathers. A signal pulse experiences frequency shift, and its velocity changes correspondingly resulting in a time delay. The restrictions on the group velocity detuning and dispersion parameters are obtained and approved by numerical simulation.

The resonant hyper-Raman scattering of light by LO and TO phonons is theoretically investigated in a rutile crystal, taking into account the Wannier excitons as intermediate virtual states. Different scattering mechanisms are considered.

A model of nonlinear optical system surrounded by two loops of feedback is investigated. The cell with the vapor of rubidium Λ - type atoms is taken in the capacity of nonlinear element. Two modes of near-resonant electromagnetic field interacting with the cell are involved in the feedback. Two-dimensional optical bistability domain in location of input field intensities is obtained and dependence of its form and magnitude from the system parameters (photon detunings, feedback factor etc.) is investigated. "Input -output" relations corresponding to different trajectories in the bistability domain are obtained. Cross-hysteresis is studied.

The effect of nonlinear polarization rotation of elliptically polarized laser pulses in solutions of fullerene (C₇₀) in organic solvents and their mixtures has been experimentally studied. The nonlinear refractive index n₂ and nonlinear cubic susceptibility Reχ⁽³⁾ (ω;ω,ω,-ω) of these solutions have been defined. The correlation between the process of C₇₀ cluster formation in solutions and the angle of self-induced polarization rotation of passing laser beam was demonstrated. The physical mechanism of self-induced optical activity in solutions is discussed.

The paper show results of research effect of powerful pulse-periodic laser radiation on the structure of Raman and absorption of some amino acids. The changes in the structures of the molecules was identified under radiation.

The energy spectrum of the collective elementary excitations of a 2D electrom-hole (e-h) system situated in a strong perpendicular magnetic field in a state of Bose-Einstein condensation (BEC) with wave vector k=0 was investigated in the frame of Bogoliubov theory of quasiaveraes. The starting Hamiltonian describing the e-h system contains not only the Coulomb interaction between the particles lying on the lowest Landau levels(LLLs), but also the supplementary interaction due to their virtual quantum transitions from the LLLs to the excited Landau levels and return back. This supplementary interaction generates after the averaging on the ground BCS-type state wave function the direct Hartree-type terms with attractive character, the exchange Fock-type terms giving rise to repulsion as well as the similar terms arising after the Bogoliubov u - v transformation. The interplay of these three parameters gives rise to the resulting different from zero interaction between the magnetoexcitons with wave vector k=0 and to stability of their BEC as regards the collapse. It influences also on the single particle energy spectrum as well as on the collective elementary excitations. It consists from six branches. Four of them are excitonic-type branches, two of them being of exciton origin whereas the second two are the quasienergy branches representing the mirror reflection of previous two branches. Another two branches are the optical and acoustical plasmon branches.

We propose and theoretically investigate a two-photon four wave mixing experiment to probe for BEC of excitons in Cu₂O thin films. A relatively simple set of equations describing the dynamics of the system is obtained for a particular configuration of the exciting beams, and numerical and approximate analytical solutions are found. The resulting phase-conjugated signal vs. the delay time between the pump and probe pulses yields a direct measure of the time evolution of the exciton condensate, and exhibit peaks when the film thickness is a multiple of a half wavelength of light.

The possibility was investigated to compress and to split laser pulses at their nonlinear optical transmission through thin semiconductor films.

A theoretical and numerical analysis of the transmission of phase modulated laser pulses through a thin film with excitonic nonlinearity is performed. It is shown that, by choosing the modulation law, one can efficiently control the optical nonlinearity of the film down to the inversion of the sign of nonlinearity.

We report the fabrication of nanoparticle gold thin films by DC magnetron sputtering and characterization of their nonlinear optical properties. Nonlinear optical response was investigated by moiré deflectometery technique using 5mW He- Ne laser (632.8 nm) illumination. All prepared films were characterized by XRD and UV-VIS-NIR spectrophotometry. The measured thermal Nonlinear refractive index (n₂=-2.2×10^-5 cm² W^-1) makes it promising for applications in all-optical switching devices and optical data storage systems.

The method of temporal laser pulses shaping based on stretching-compressing and profiling of a pulse by volumetric chirped Bragg gratings is proposed and realized in ps-duration range. Experimental results of the study are presented.

The direct observation of gamma-ray laser radiation on wavelength λ ≈ 0.2 nm have been carried out from tantalum-181 plasma, produced by picosecond ND:YAG laser (under an additional influence of external electric field and without them). It had been established that duration of such radiation in mode of ASR ("Amplification of Spontaneous Radiation") approximately equals 1-3 ns on the background of isotropic distribution of intensity the strongly directed components along micro plasma jets. Such gamma-ray laser radiation penetrates throw Be-filter (thickness 130 μm) from vacuum chamber into atmosphere, where the gamma-holograms were produced in closed box. So the coherence of generated gamma-ray radiation can be confirmed by the first our gamma-holograms production. Few examples of gamma-holograms and its images of different micro objects are considered. The constructed compact gamma-ray facility and developed gamma-ray holographic method will be very useful to experimental investigations in area of microbiology, genetics and etc.

The natural laws of the nonlinear absorption in the nanoporous glass polymer composite doped with phthalocyanine and porphyrin dyes is investigated experimentally using 24 nanosecond (FWHM) 532 nm laser pulses. The nonlinear absorption in the network of the four-level model is analyzed theoretically. It is demonstrated that theoretical result and experimental data have a good agreement.

It is shown that when an s-polarized wave is mixed with a normally incident wave of the same frequency, it is possible to generate an s-polarized second harmonic wave in the metal skin-layer. The effect of the electron and lattice temperature evolution on the SHG efficiency is quantitatively described. An anomalously strong change in the generation efficiency of this harmonic is found due to electron heating.

The nonlinear refraction and nonlinear absorption of 40 nanosecond (FWHM) 532 nm pulses through the samples made of nanoporous glass polymer composite doped with phthalocyanine and porphyrin dyes is investigated. The laser damage resistance of 28 nanosecond (FWHM) 532 nm pulses in nanoporous glass polymer composite is measured. It is demonstrated that the nanoporous glass polymer composite is a good solid-state host material for nonlinear element of laser optics.

The influence of the Rashba spin-orbit coupling on the two-dimensional (2D) electrons and holes in a strong perpendicular magnetic field leads to different results of the Landau quantization in different spin projections. In Landau gauge the unidimensional wave vector describing the free motion in one in-plane direction is the same for both spin projections, whereas the numbers of the Landau quantization levels are different. For electron in s-type conduction band they differ by one, as was established earlier by Rashba1, whereas for heavy holes in p-type valence band influenced by the 2D symmetry of the layer they differ by three. There are two lowest spin-splitted Landau levels for electrons as well as two lowest for holes. They give rise to four lowest energy levels of the 2D magnetoexcitons. It is shown that two of them are dipole-active in band-to-band quantum transitions, one is quadrupole-active and the fourth is forbidden. The optical orientation under the influence of the circularly polarized light leads to optical alignment of the magnetoexcitons with different orbital momentum projections on the direction of the external magnetic field.

This work is devoted to study of the strong selective reflection of obliquely incident laser beam (inclined geometry) from the interface "glass-rubidium vapour". It is shown that the contrast of the strongest refection resonances exceeds 500% at the moderate heating of reflecting cells. The new nonlinear properties of selective reflection resonances have been investigated - asymmetry of saturation of resonant total internal reflection (TIR) and nonlinear structures that appear under conditions close to resonant TIR. The observed structures can not be associated with well-known sub-Doppler resonances in selective reflection. The nonlinear structures described here do not have saturation properties in usual sense. They exist only in the inclined geometry and in a narrow range of saturating values of the surface power density at the interface. The transformation of the fluctuations of reflected light was also investigated at the optical saturation of selective reflection resonances. For this purpose the intensity of incident light was slightly modulated. The reduction of the corresponding intensity modulation was registered in the reflected light. This reduction of the intensity fluctuations ("classical squeezing") and the relatively high selective reflection coefficient offer good possibilities for the squeezing of quantum fluctuations in the reflected light. In the process of appropriate studies it was found that the reduction (squeezing) of photons (quantum) fluctuations in the reflected light beam is about of 5% in compare with the coherent light.

We present in this article a new mid-IR source delivering up to 1W of power at 100kHz. Based on a OPCPA system it can deliver pulses with a duration down to 67fs with an energy of 3.8μJ at a centre wavelength of 3.2 μm. Those pulses have been measured with a high resolution FROG measurement tools developed for the mid-IR application.

Simultaneous generation of the 2nd and 3rd harmonic, excited by linearly frequency- chirped fundamental pulse in quasiphase matched grating with linearly varying inverse domain sizes has been studied numerically with taking into account effects of the group velocity mismatches and dispersions. Mechanisms of efficient nonlinear pulse compressions and conversion efficiencies of the generated harmonics have been analyzed.

Research of a Doppler shift of frequency of the Nd-laser pulse radiation reflected from a laser plasma in air, using the KD*P electrooptic cell is carried out. Under these conditions the dependence of a half-wave voltage of a cell on a wavelength is used. Velocity of electrons in laser plasma is obtained to attain the peak meaning 1% from light velocity.

We proposed a simple laser system controlled by optimally adjusted combination of inertial negative and positive feedbacks capable to demonstrate the nonlinear regular and chaotic dynamics on the time scale of the laser cavity round trip time. The numeric simulation proved that such a system can be realized on the basis of the optoelectronically controlled solid state laser.

The non-stationary theory of the pump-probe method of investigation of the optical properties of semiconductors in the exciton range of spectrum taking into account the exciton-photon and elastic exciton-exciton interactions was elaborated. The time evolution of the exciton density and the imaginary component of the susceptibility for the different shapes of incident strong pulse were investigated.

Optical wave thermalization is a process characterized by an irreversible evolution of the field toward a thermodynamic equilibrium state. We study the influence of third-order dispersion on the thermalization of an optical wave propagating in a single mode optical fiber (1D nonlinear Schr¨odinger equation). The optical field exhibits a process of anomalous thermalization: It relaxes toward an equilibrium state of fundamental different nature than the thermodynamic equilibrium state. The spectrum of the wave is shown to exhibit a highly asymmetric deformation characterized by a lateral spectral shoulder and the subsequent formation of a constant spectral pedestal. The wave turbulence theory reveals that this anomalous thermalization is due to the existence of a local invariant in frequency space, which explains in detail the essential properties of the highly asymmetric spectral evolution of the wave.

The geometry of Raman shifter with self-intersection of pumping beam is proposed. The generation of a Stokes wave takes place in a separate ring resonator with a non-linear parametric mirror. The spatial location of a ring resonator with respect to pumping waves has determined. For this geometry conditions of the phase matching and effective interaction of waves at different frequency mixing are realized. The scheme allows to essentially expand spectral range of SRS converters.

For the phase conjugated wave at four-wave mixing at SBS the transient analytical solution is obtained. A rate of the reflected wave amplitude increasing and a range of values of coupled waves parameters in which time instability is most essential are determined. Conditions of attenuation of absolute instability influence on considered process of phase conjugation are noted.

Details of interaction between the blackbody radiation and neutral lithium atoms were studied in the temperature ranges T = 100-2000 K. The rates of thermally induced decays, excitations and ionization were calculated for S-, P- and D-series of Rydberg states in the Fues' model potential approach. The quantitative regularities for the states of the maximal rates of blackbody-radiation-induced processes were determined. Approximation formulas were proposed for analytical representation of the depopulation rates.

We discuss progress towards a precision measurement of the atomic recoil frequency in ⁸⁵Rb using an echo-type atom interferometer. We report a single measurement precision of ~ 300 ppb on a timescale of ~ 50 ms.

Two-pulse photon echo in LiLuF₄:Er³⁺ crystal subjected to a weak pulsed magnetic field is investigated. The dependence of the echo intensity on the magnetic field switching time is analyzed. Prospects for using photon echo modulation by a weak magnetic field for photon-echo-based storage are discussed.

The teleportation of entangled optical images is for the first time considered. The scheme offered is based on process of four-partite state generation in coupled parametric interactions realizing in an aperiodic nonlinear photonic crystal. The coupled nonlinear optical process consists of one parametric down-conversion process which is followed by two up-conversion ones. We study nonclassical properties of the generated fields by analyzing the EPR correlations for different pairs of modes and carry out the comparison of the EPR correlations of the input and images output images and also calculate fidelity of the teleportation exploiting the covariance matrices of the images. We take into account the difference of spatial frequency bandwidths of the entangled images and fields generated in the coupled process. It has been established that under certain parameters of the scheme one can be obtain rather high fidelity of the teleportation and good preservation of the quantum correlations of the input images for all details of the images.

Generation of the electronic waves with high degree of coherence becomes a physical reason for developing holographic electronic microscopy with high resolution and creating the technology of holography for low energies. This effect opens an opportunity to design new tools for observation of the nanometer scale objects without destruction. The general picture can be considered in the approximation of the steady-state wave function. The outgoing wave is described by the amplitude slowly varying along the trajectory. Quantum formulation of photodetachment of a negative ion as the steady-state process is equivalent the inhomogeneous Schrödinger equation. Its solution can be expressed in terms of the Green's function. The exact expression for the Green's three-dimensional function is known in two cases: homogeneous electric field and the Coulomb field. The detailed picture for distribution of photocurrent in a homogeneous field demonstrates the advantages of the quantum theory approach. We found the repulsive Coulomb field is more effective for extension the area of the interference pattern at a small distance from an ion.

We investigate the coherent population trapping (CPT) resonances excited in rubidium atoms by the femtosecond optical comb in magnetic field. The light shift of resonances was observed and studied.

We study Rydberg atoms in ponderomotive optical lattices. Unlike for ground-state atoms, for Rydberg atoms in an optical lattice the extent of the electronic wave-function can approach the lattice period. This leads to state-dependent adiabatic trapping potentials that are unique to Rydberg atoms. We first discuss a theoretical model of adiabatic lattice potentials of Rydberg atoms. Then, we use microwave spectroscopy to experimentally demonstrate and investigate the state-dependence of the adiabatic potentials of S_1/2 Rydberg states of rubidium. The observed microwave spectra depend strongly on both the principal quantum number and the depth of the lattice. A semi-classical simulation is used to explain the features seen in the spectra. Based on the results, we estimate the trapping efficiency of the ponderomotive optical lattice.

The collisions at ultracold temperatures between ¹Σ state diatomic polar molecules in a microwave field with a circular polarization are theoretically analyzed. We demonstrate the possibility of trapping polar molecules in the standing-wave electromagnetic field and a successful evaporative cooling not only for samples of molecules in their absolute ground states but in some rotationally excited states in the appropriate regions of frequencies of a field. Here we only discuss fermionic polar molecules at ultralow temperatures(1μK), considering RbK as a prototype.

Theoretical study and computer modeling results of the spectra of coherent dark resonances resulted from excitation of Zeeman sublevels of the F_g=2→F_e=1 transition of the D1 line in ⁸⁷Rb atoms by a frequency-modulated laser field are presented and discussed in detail. The influence of the nonlinear Zeeman effect on the structure of the coherent dark resonances is observed. It is shown that calculated for different values of the magnetic field spectra are in a good agreement with the experimental data.

Dynamics of atoms trapped in an optical dipole trap formed by a train of femtosecond laser pulses is studied in detail on example of Rb atoms. In computer simulation, it is proved that such a trap effectively confines the atoms at the pumping laser beam power in between 1 mW and 3 kW (pulse duration 100 fs). It is also shown that the resonant dipole-dipole interaction (RDDI) through which closely spaced in the micropotential wells atoms interact between each other becomes essential and can be significantly increased by shining the atoms with resonant probe laser beam. Varying both the parameters of the trap and intensity of the probe laser field, role of the RDDI in the atomic dynamics in the trap is clarified in detail.

Terawatt hybrid (solid state/gas) laser (THL-100) system on the basis of Ti:sapphire starting complex (50 fs, 5 mJ) and photochemical XeF(C-A) amplifier with the aperture of 24 cm is presented. Laser system is built at Institute of High Current Electronics SD RAS, Tomsk, Russia. The design and peculiarities of optical pumping of XeF(C-A) amplifier, methods of pump power measuring, gain distribution across the active volume are discussed. The results of numerical modeling of the output parameters simulation are presented and one compared with first experimental results.

A new method of the measurement of the maximal laser pulse intensity at the focal spot is suggested. The measurement of the energies of electrons ejected from the focal spot by laser radiation is used.

The radiation emitted by an electron driven by a relativistically intense laser field comprises a set of electromagnetic pulses with complicated spectral structure having durations much shorter than the optical cycle.

The process of the light scattering becomes nonlinear in the fields with relativistic intensity. Nonlinear scattering of ultrashort relativistic pulses by free electrons is considered. We use the wavelet basis in the form of derivatives from the Gaussian function for description of ultrashort pulses. The equation of motion, for a charged particle in the field of plane electromagnetic wave, has the exact solution including the expression for the energy. The approximation of instant spectrum allows to calculate the Thomson nonlinear scattering for laser pulses of ultrarelativistic intensity. Spectral distribution for all the pulse duration is the result of integration over the time. Exact solution in the case of laser pulse with form of the "Mexican hat" gives the velocity and acceleration in the parametrical form as functions of the proper time. The maximum of radiation for free electron in the fields with intensity 10¹⁹-10²¹ W/ cm² is concentrated at the range of ultraviolet spectrum with photons energies 3-12 eV. The part of continuous spectrum reaches the area of large photon energies. One percent of scattered energy for the laser intensity 10²⁰ W/ cm² is concentrated at the range hω > 2,7 x 10² eV, 10²¹ W/ cm² - hω > 7,9 x 103 eV, 10²² W/ cm² - hω > 2,45 x 10⁵ eV. It allows one to use nonlinear scattering as a source of hard x-ray radiation.

We report laser filamentation in the bulk of chalcogenide glass with femtosecond laser pulses of energy on the nanojoule level. Spatially resolved measurements of the resulting refractive index modification are presented. The study of the pulse energy and focusing condition dependencies show that channels of positive refractive index variation of several millimeter length can easily be obtained.

The interaction of two femtosecond filaments has been studied in single-crystal sapphire at small crossing angles 1.2° ÷5°. Regular multifilament pattern (MFP) can be formed in the overlapping area of two beams, which depends on the pulse energy, crossing angle, and phase difference. As a special realization of MFP, formation of a single filament from two different pump beams was for the first time observed. The number of filaments in the MFP depends on the number of the interference maxima in overlapping area, whose power exceeds critical power for self-focusing. We demonstrate control of multifilament pattern, changing the phase shift between the interacting beams. Attraction and repulsion of the filaments is observed in vicinity of the overlapping region for both in- and counter-phase beams depending on the position Z along the propagation axis. Transformation of near- and far-field images of the single filament, formed by two pump beams, and spectra of its axial emission have been studied depending on the filament length. It has been shown that four-wave mixing plays a major role in forming the axial emission spectrum.

The 3D particle-in-sell (PIC) simulations of interaction of short high-intense laser pulses with solid state targets (ultrathin double-layer foils and homogeneous targets consisted of heavy and light ions) and low-density targets (dense gas jets or aerogels) have been performed. It has been shown that gas jet targets have no any advantage in comparison with ultrathin foils in terms of maximum proton energy and spectrum quality. The utilization of mass-limited foil of submicron thickness allows one to increase efficiency of high-energy particles production. As a result, the mono-energetic proton beams with energy of hundreds mega-electron-volts can be generated by the laser pulses with energy of the order of tens of joules. The best performance of the ion sources discussed is achieved by proper matching of laser pulse intensity, pulse duration, focal spot size and target density.

The wild-type phototropin protein phot from the green alga Chlamydomonas reinhardtii consists of two N-terminal LOV domains LOV1 and LOV2 with flavin mononucleotide (FMN) cofactor and a C-terminal serine-threonine kinase domain. It controls multiple steps in the sexual lifecycle of the alga. Here the LOV1-His domain of phot with modified cofactor is studied. FMN is replaced by roseoflavin monophosphate (8-dimethylamino-8-demethyl-FMN, RoFMN). The modified LOV1 domain is called RoLOV1. The photo-dynamics consequences of the cofactor change are studied. The absorption, emission, and photo-cyclic behaviour of LOV1-His and RoLOV1-His are compared. A spectroscopic characterisation of the cofactors FMN and RoFMN (roseoflavin) is given.

The ultrafast e^--bunches produced by femtosecond laser (fsl) radiation are powerful tool in modern physics to observe different ultrashort processes induced by fsl pulses and to reach high spatio-temporal resolution. In Letokhov's projection microscope such a beam transfers an information from a tip with a sample illluminated by fsl pulses to a detector. Here the fsl radiation provides for an effective photoelectron multiphoton emission without significant heating of the sample. Two organic samples, formed from dye molecules and the organic conducting polymers has been vizualized using the nanocapillary as a tip. The advantages of the nanocapillary tip are described in the report. The temporal resolution depends upon the pulse duration of the e^--beam, τ_e. One of the most powerful way to measure τ_e is to use the Gaponov-Miller force (GMf), or the ponderomotive force, which the electrons experience in the inhomogeneous field of a focused laser pulse. Such a force helped us to demonstrate the «instantaneousness» of multiphoton emission process from solid targets. As the beam propagated, it spread in time. Using GMf we temporally characterized the e^--pulse transmitted through microcapillary (which can be the basis of the promising scanning microscope) and combined spatial nanoresolution and picosecond temporal resolution. Also the ultrafast microlocalized e^--beam is an ideal tool to measure the GMf created by focused fsl pulses and to characterize very intense laser beam profile in-situ. In principal, such approach may allow for direct subwave spatio-temporal probing of superintense laser beam profiles.

According to the scheme of the Stern-Gerlach experiment, upgraded by adding of a powerful laser-plasma electronemitting source from a metal target, an experimental research has been carried out showing the key opportunity of generation of electronic streams with the oriented spin.

An high sensitivity laser gyroscope is presented operating in a square cavity of side length of the order of 1 m with a measured sensitivity limit at the level of 2 · 10^-9(rad/s)/ √Hz. We report on the active stabilization of the laser optical frequency which is mainly driven by the environmental thermal fluctuations and the experimental results obtained with the active stabilization system are given. Finally the applications of this gyrolaser as an high-sensitive tilt-meter in Virgo, the large-frame interferometer for gravitational waves detection, are discussed.

Here we report on absolute frequency measurements of a commercial high power CW diode-pumped solid-state laser (Coherent Verdi-V5). This kind of lasers usually presents large frequency jitter (up to 50 MHz) both in the short term (1 ms time scale) and in the long term (>10 s time scale). A precise measurement of absolute frequency deviations in both temporal scales should require a set of different devices (optical cavities, optical wave-meters), each suited for measurements only at a specific integration time. Here we demonstrate how a frequency comb can be used to overcome this difficulty, allowing in a single step a full characterization of both short (<1 ms) and long term (> 10³ s) absolute frequency jitter with a resolution better than 1 MHz. We demonstrate in this way the flexibility of optical frequency combs for absolute frequency measurements not only of ultra-stable lasers but also of relatively unstable lasers. The absolute frequency calibration of the Verdi laser that we have obtained have been used in order to improve the accuracy of the measurements of the local gravitational acceleration value with ⁸⁸Sr atoms trapped in 1D vertical lattices.

Ultrafast dynamics of bismuth excited by femtosecond laser pulses was studied varying wavelength of pump and probe pulses from 400 to 2500 nm and from 400 to 900 nm respectively. Three relaxational components with decay rates of 1 ps, 7 ps and ~ 1 ns were found in the photoinduced response. The fastest process is ascribed to the excited electrons at T₆⁺ point of the Brillouin zone, that are responsible for coherent A_1g phonon generation and its frequency softening. Intermediate component is due to crystal heating via electron-phonon interaction. Finally, a long-lived nanosecond signal is linked to electrons near the Fermi level at L_s point.

By means of pulsed laser spectroscopy applied to muonic hydrogen (μ¯p) we havemeasured the 2S (F=1)/(1/2) - 2P(F=2)/(3/2) transition frequency to be 49881.88(76)GHz.¹ By comparing this measurement with its theoretical prediction ^2-7 based on bound-state QED we have determined a proton radius value of r_P =0.84184(67) fm. This new value differs by 5.0 standard deviations from the CODATA value of 0.8768(69) fm,⁸ and 3 standard deviation from the e-p scattering results of 0.897(18) fm.⁹ The observed discrepancy may arise from a computational mistake of the energy levels in μp or H, or a fundamental problem in bound-state QED, an unknown effect related to the proton or the muon, or an experimental error.

Nanocomposite materials on the basis of semiconductor nanoparticles such as CdS are special interest for use in many fields of a science and technique: optics, electrochemistry and optoelectronics. Non-linear optical properties of the composite materials depend on a size, a shape and features of synthesis methods. The sample was investigated is a film of 0.3 mm thickness. The size of nanoparticles (2.5 nm) was characterized by method of X-ray powder diffraction. The green luminescence in 529 nm range is due to the radiative recombination of electron-hole pairs. The red luminescence in 640 nm range is due to the radiative recombination of the exciton trapped in the nanocomposite defect states. We observed the generation of the second harmonic in the range of 400 nm by pumping 790 nm laser pulses. The luminescence intensity I in the range of 400 nm and 529 nm as a function of the excitation density energy P are correspond to the function I ~ Pⁿ. For the band at 529 nm range n =3 that correspond two- (400 nm) and three- (267 nm) at 800 nm excitation.

The reversible and irreversible structural transformations of monomolecular and associated nanocomponents of a polymethine dye layer by photoexcitation or heating are studied experimentally. The photo- and thermodestruction yields of the layers are investigated.

Various single colloidal quantum dots were investigated in chiral liquid crystal 1-D photonic bandgap microcavities for visible and telecom wavelengths. The microcavity environment provides circular polarization of definite handedness. Narrow, circularly-polarized microcavity resonances of 3-5 nm width were observed on the band edges of the stopbands.

Experimental results of two room-temperature, robust and efficient single-photon sources with definite circular and linear polarization using single-emitter fluorescence in cholesteric and nematic liquid crystal hosts are discussed. For single emitters, we used nanocrystal quantum dots, single color centers in nanodiamonds, and single dye molecules. Single-photon sources based on single emitters in liquid crystals are the room temperature alternatives to cryogenic single-photon sources base on semiconductor heterostructured quantum dots in microcavities prepared by molecular beam epitaxy.

This research presents a design of simple interference anti-reflection coating consisting of a transparent host and uniformly oriented disc-like silver nanoparticles. This work explores the utility of effective medium representations to simplify the electromagnetic analysis of composite system, and demonstrates the use of this simplification in solving of the boundary problem under consideration. With the help of full-wave finite-element numerical analysis, it is shown that effective-medium approach provides a satisfactory qualitative description of the reflection and transmission spectra in composite layers and confirms their antireflective behavior.

Optical properties of an ultra-thin composite layer consisting of a transparent dielectric with inclusion of silver ellipsoidal nanoparticles are investigated theoretically. It is shown that anisotropic plasmonic absorption in nanoparticles leads to polarization-dependent reflectance and transmittance of composite layer.

The anomalous nonlinear absorption of colloidal CdSe/ZnS quantum dots has been revealed in the case of resonant excitation of the basic exciton transition by powerful picosecond light pulses: bleaching at moderate input intensities is substituted by retardation of bleaching rate and even by increasing of absorption. The latter has been explained by saturation (state-filling) effect of two-level system with decreasing lifetime of the excited state at high excitation because of Auger recombination. The observed changes of output intensity cross-section profile versus exciting intensity were attributed to the creation of transparency channel in the cell with highly absorbing colloidal solution of quantum dots by laser beam due to state-filling, strip-effect and finally self-diffraction of Fresnel or Fraunhofer type by induced aperture.

Vibrational wave packets in chloroform and gold colloid in chloroform were studied by femtosecond pump-probe spectroscopy. It was found that the main modes of oscillations for both systems coincide with the frequencies of the Raman resonances of chloroform 260 cm^-1, 367 cm^-1 and 668 cm^-1. The effect of gold nanoparticles leads to 4-6 fold increased signal of Raman resonance of pure chloroform.

We review current status and perspectives of nanolithography via atom optics and its application in production of nanophotonics and nanoplasmonics elements: gold optical nano antennas, plasmonic wave guides, nanostructures formed by organic molecules.

Time-integrated and time-resolved laser spectra for two zinc oxide complex structures mainly consisting of tetrapods and structures of nanowire type were investigated under nanosecond pumping. Simplified models of observed lasing modes are suggested on the basis of multiple total internal reflections and analyzed numerically basing on the experimental results and using spectrum of single tetrapod from Ref.9.

Bright two-photon luminescence of gold and silver nanoparticles photodeposited in titanium dioxide matrix was studied under near IR laser pulse irradiation. Electromagnetic field enhancement coefficients were estimated for the most intense hot spots at wavelength of excitation. The estimation was compared with theoretical predictions of FDTD analysis.

The optical reflection and transmission spectra of a metallic nanograting are studied. It is shown that the specific feature of nanograting reflection spectra is the presence of a few resonant dips.

The light transmission through metallic films with different types of nano-structures was studied both theoretically and experimentally. It is shown, analytically, numerically and experimentally, that the positions of the surface plasmon resonances depend on the nano-structural details. Those can be changed from sample to sample or in given sample by applying an external dc electric or magnetic field. The dependence of transmission spectrum on the shape of holes (inclusions) and external fields can be used for manipulation of the light transmission, as well as the polarization of the transmitted light and other optical properties, by external field. Two complementary situations are considered: a metal film with dielectric holes and a dielectric film with metallic islands. In the case of metallic islands, we propose two ways of controlling plasmon resonance frequency: changing the aspect ratio of the elliptical (or rectangular) islands and changing their mutual distances. For this case a new analytical asymptotic approach for calculating the optical properties of such plasmonic systems is developed. The results of our analytical and numerical studies are in good qualitative agreement with experiment.

Recent results on the interaction of high power laser pulses with various dielectric materials containing metal nanoparticles are reviewed. The excimer laser pulse modification of silver nanoparticles synthesized by ion implantation in soda-lime silicate glasses are considered. One of features of composite samples prepared by the low energy ion implantation is the growth of metal particles with a wide size distribution in the thin depth from the irradiated substrate surface. Pulsed laser irradiation makes it possible to modify such composite layer, improving the uniformity in the size distribution of the nanoparticles. Changes induced by pulsed laser exposure suggest there are both reductions in average size of the metal nanoparticles, and some long-range dissolution of metal atoms in the matrix. Experimental data on laser modification are explained by melting of the nanoparticles in the dielectric matrix.

Recent results on synthesis of silver nanoparticles by ion implantation in various dielectrics are presented. Composites demonstrate specific nonlinear-optical properties such as saturated and two-photon absorption in visible spectral area.

We present Raman and infrared studies on the structures of organic semiconductor thin films used for electronic devices. The Raman spectra of crystalline and amorphous states of an organic semiconductor, N,N'-di-1-naphthaleyl-N,N'-diphenyl-1,1'-biphenyl-4,4'-diamine (NPD), were measured. These states give rise to slightly different peak positions and widths of each Raman band. Raman images were observed for polycrystalline pentacene films evaporated on a silicon substrate. The structural defects were found in the images of the intensity ratio I₁₅₉₆/_I1533, which reflects the orientation of molecules i.e., crystalline domains. Photoinduced infrared absorption from the composite of regioregular poly(3-dodecylthiphene) and C₆₀ was measured by the difference FT-IR method. The observed absorption is attributable to photogenerated carriers. The action spectra of photoinduced infrared absorption are explained by electron transfer from photogenerated excited states on a polymer chain to C₆₀.

Typically, amorphous organic materials contain high density of traps. Traps hinder charge transport and, hence, affect various working parameters of organic electronic devices. In this paper we suggest a simple but reliable method for the estimation of the concentration of deep traps (traps that keep carriers for a time much longer than the typical transport time of the device). The method is based on the measurement of the dependence of the total charge, collected at the electrode, on the total initial charge, uniformly generated in the transport layer under the action of a light pulse. Advantages and limitations of the method are discussed and an experimental example of the estimation of the density of deep traps in photoconductive organic material poly(2-methoxy-5- (2'-ethylhexyloxy)-1,4-phenylenevinylene (MEH-PPV) is provided.

The lateral photocurrent caused by anisotropic momentum distribution of photoelectrons in semiconductor excited by linearly polarized femtosecond laser radiation is calculated analytically and numerically with the use of particle method. We have considered three mechanisms of this effect: diffusive scattering of photoelectrons on the surface, nonparabolicity of conduction band and dependence of electron momentum relaxation time on energy. It has been shown that contributions of the lateral and normal photocurrent components to terahertz emission can be comparable.

The generation of terahertz broadband pulses by optical rectification in nonlinear crystal under condition of laser pulse interaction with quantum particles with permanent dipole moment is examined. If the permanent dipole moment is larger than transition dipole moment, the resonant method is more efficient than nonresonant optical rectification. Estimated conversion efficiency in organics and semiconductor nanostructures can reach 0.1% and higher on order of magnitude.

An exploration of THz range causes the necessity of dynamic control over the parameters of the radiation - modulation of its intensity, phase and polarization. In this range optical properties of semiconductors are mainly defined by the interaction of radiation with semiconductor plasma. A strong influence of the external field on parameters of a plasma of any kind, including the carrier plasma, opens possibilities for controlling parameters of THz radiation. The characteristic modulation time is defined by the carriers relaxation time (about 10^-12 s), i.e. has the same order of magnitude as a THz wave period. For the calculation of an influence of an external quasi-static electric field on the parameters of the plasma and on the optical properties of the semiconductor all main mechanisms of carrier scattering and relaxation were accounted. For AIIIBV semiconductors the calculations of the response of the complex permittivity of carrier plasma on the external field were done numerically. An analysis of the reflection coefficients based on generalized Fresnel equations showed a variation of the reflection coefficient of the semiconductor under the influence of the field by dozens percent. Static parameters of semiconductors which provide a maximum modulation depth were defined. In case when an external field is a THz band field itself, the dependence of the permittivity on the intensity results in the harmonics generation. An analysis of the specific features of the generation showed an appearance of frequency resonances and a unique non-monotonic way of the dependence of the harmonic intensity on the pump wave field.

Effect of the preliminary irradiation of bovine serum albumin (BSA) in the terahertz spectral range on the conformation changes revealed with the help of EPR spectroscopy was investigated using the spin probing technique. The formation of the spin probe occurs directly in the aqueous solution of BSA from a nitrone compound (dihydropyrazine dioxide). It was shown that irradiation causes changes in the parameters of the EPR spectrum of the spin probe. An approach to linking the observed changes with the structural characteristics of reaction centres - the functional groups of amino acids comprising BSA - was outlined.

In the present paper the results of the study of semiconductor and optical properties of GaSe crystals important for their applications in nonlinear optics of terahertz and mid-IR ranges are reported as well as influence of doping with isovalent chemical elements on them. The performed first-principles calculations of charge neutrality level (CNL) in GaSe have shown its position at 0.8 eV above the top of the valence band. The location of CNL in the lower part of the band gap can explain GaSe intrinsic p-type of conductivity. In this case it is necessary to radically improve the growth technology to obtain GaSe crystals with low free carrier concentrations. Extraordinarily large birefringence of GaSe B~0.8 in terahertz range has been measured directly. In order to study the potential efficiency of application of doped GaSe crystals for terahertz generation and detection their study using terahertz time domain spectroscopy (THz-TDS) setup has been performed. According to the obtained results doped GaSe crystals are slightly less efficient for terahertz detection and generation in the frequency range 0.2-3.2 THz via optical rectification of laser pulses with λ=790 nm and τ=80 fs. On the other hand doping of GaSe with In, Al, S, Te leads to 2-3 times increase of the microhardness and the doped crystals become suitable for the mechanical treatment.

Irradiation (1, 2 or 3 hours) of elite wheat grains by THz radiation (3,68 THz) induces a shortening of seed imbibition period. The most pronounced effect was observed after two hours of irradiation. Irradiation of 3rd class seeds does not influence seed imbibition period. It is assumed that shortening of imbibition period caused by THz radiation influence on conformation of m-RNA and proteins of endosperm cells that regulate a water movement into grains. THz radiation induces an increase of stem and panicle length, panicle mass, grain number in panicle and grain protein content. These changes can be conditioned by influence of THz radiation on seed genetic system.

Terahertz emission from indium arsenide excited by femtosecond laser pulses was numerically simulated with the use of particle method. It is shown that the largest terahertz emission is achieved when 800 nm femtosecond laser pulses are used for excitation of InAs. We describe terahertz time-domain spectroscopy setup built that uses a relatively simple terahertz emitter on the basis of indium arsenide plate.