This PDF file contains the front matter associated with SPIE Proceedings Volume 6599, including the Title Page, Copyright information, Table of Contents, Introduction, and the Conference Committee listing.

An analysis of the spectroscopic properties of trivalent erbium doped Yb₃Al₅O₁₂ (YbAG) garnet is presented. In this work, the authors focused attention on the up-conversion processes leading to the short wavelength emission from the ²G_9/2, ⁴S_3/2 and ⁴F_9/2 excited states of Er³⁺ ions. The strong interaction between Yb³⁺ and Er³⁺ ions, responsible for the infra-red (940 nm) induced visible emissions in the 415, 550 and 670 nm range, were observed.

The paper presents results of investigations of 3D matrices of excitation-emission luminophores for semiconductor sources of white light. Various crystalline media doped with cerium ions were examined. Influence of crystalline structure and additional dopants on emission characteristics of potential luminophores was stated.

Design and fabrication of saturable Bragg reflectors (SBRs) by molecular beam epitaxy (MBE) is presented. Grown structures consisted of AlAs/GaAs quarter-wave layers with low-temperature InGaAs/GaAs quantum wells (LT QWs) as saturable absorber layers. Special emphasis is put on methodology of wavelength tailoring of distributed Bragg reflectors and on MBE technology of growing the quantum wells with the recombination time of excitons of the order of tens ps. Application of different methods of characterization of LT QWs and SBRs for testing and optimizing the MBE process is discussed.

This paper features modelling the response of superconductor switching elements, carried out for the structures composed from a film of YBa₂Cu₃O_7-x deposited onto substrates SrTiO3 or Al2O3, controlled by current and laser pulses with the length of 5&mgr;s. Based on these responses, threshold characteristics of switching and optimal (respectively to the operation speed) control characteristics were obtained.

Nonlinear propagation of laser beams in 1D array of optically induced waveguides is investigated. The array is generated by two stationary plane waves and third steering wave interfering in slab waveguide core made of photorefractive material with a quadratic electrooptic effect. The possibility of controlled propagation of light by change of parameters of steering wave is analysed.

The paper presents the results of spectroscopic and energetic resistance investigations of anti-laser protective filters of various optical constructions. For filters development, various material technologies were used, including melting technologies of silicate and phosphate glass, doped with various dopants selectively absorbing radiation in a given spectral range, and technologies of thin-film coatings. Spectral properties of filter glass were modified by interference dielectric coatings so, filters selective at several wavelengths. Such filters fulfil requirements of higher transmission in a visible range, higher energetic resistance, and better vision contrast. They also improve work comfort during long lasting operation.

In the paper, a technique termed time-resolved spectra mapping, developed to assess thermo-optical properties of pulse operating lasers, is described. The technique enables measurement of the laser mode spectral characteristic at an arbitrarily elected moment within the width of the driving current pulse. The measured shift of the central mode wavelength in the spectrum envelope serves then to determine temperature change of the laser active region. The timeresolved spectra mapping technique has been found useful in evaluation of the efficiency of heat removal from lasers mounted in different packages.

In the paper, the comparative analysis of the room-temperature (RT) continuous-wave (CW) threshold operation of various designs of oxide-confined (OC) vertical-cavity surface-emitting diode lasers (VCSELs) is carried out using the 1.3-&mgr;m OC intra-cavity-contacted GaAs-based quantum-well (GaIn)(NAs)/GaAs VCSEL as a typical example. The analysis has been carried out with the aid of the comprehensive fully self-consistent three-dimensional optical-electrical-thermal- gain model. Different VCSEL designs have been found to be optimal depending on their application. An impact of the built-in radial confining mechanisms created by oxide apertures, i.e. an influence of their diameters and localizations on radial confinements of both the current injection into VCSEL active regions and electromagnetic fields of successive cavity modes, has been investigated. A new approach is proposed to enhance CW RT single-fundamental-mode operation in higher-output OC VCSELs. One of their oxide apertures should be shifted to the node position of the resonator standing wave where it is working as the electrical aperture only. Then diameters of both apertures may be changed independently giving an additional degree of freedom for VCSEL designing which enables their optimization.

The Q-switched laser with triangle slab made of Nd:YAG crystal side pumped by 600-W quasi-cw diode laser stack has been designed. The multimode (M²≈2.6) output energy of about 42 mJ was demonstrated in free running mode for 110-mJ pump energy. In Q-switch experiments, the KDDP Pockels cell was placed between the slab and rear mirror in plane-plane cavity with output coupler of 84% transmission. The energy of 8 mJ in 2.1-ns pulse duration was obtained for near TEM₀₀ output beam. For passive Q-switching by means of Cr:YAG crystal of 12.6% unsaturated transmission the energy of 5.1 mJ in 2.5-ns pulse duration was obtained for output beam close to TEM₀₀ mode.

The main properties of acousto-optic modulators (AOM) applied in laser technology are presented and discussed in the paper. The critical review of application of AOMs in several types of diode pumped solid state lasers (DPSSL) is given. The short description of few DPSSLs developed in our group is presented in the following chapters of the paper. The parameters of a simple AO-Q-switched Nd:YVO₄ laser (peak power up to 60 kW, pulse duration of 5-15 ns, repetition rate in the range 10-100 kHz, with average power above 5 W) are satisfactory for different application as follows: higher harmonic generation, pumping of 'eye-safe' OPOs etc. The achieved brightness of 10¹⁷ W/m²/srd is comparable to the strongest technological Q-switched lasers of kW class of average power. The main aim of paper is to present novel type of lasers with acousto-optic modulation namely: AO-q-switched and mode locked (AO-QML) lasers. We have designed the 3.69-m long Z-type resonator of the frequency matched to the RF frequency of AOM. As a gain medium the Nd:YVO₄ crystal end pumped by 20 W laser diode was applied. The energy of envelope of QML pulse train was up to 130 &mgr;J with sub-nanosecond mode locked pulse of maximum 30-&mgr;J energy.

Two 3x3x10 mm³ 0.3% at. Nd:YVO₄ rods, end pumped by a pair of 25-W CW high power fiber coupled laser diodes, were employed in the efficient laser based on the V-type resonator scheme. A high slope efficiency, the mitigation of the thermo-optic effects as well as optimization of energetic and spatial parameters of the laser beam for the whole range of pump power were demonstrated in such a laser operating in acousto-optic Q-switching regime. The pulses of 180-&mgr;J energy and 20-ns pulse duration up to 100-kHz repetition rate have been obtained. The pulse energy decreases and duration grows up with the increase in pulse repetition rate. The average output power of 14 W for CW regime and 10 W for Q -switching mode were accomplished for the maximum pump power. Brightness and high peak power of this laser are satisfactory to achieve efficient nonlinear conversions (generation of higher harmonics, pumping of optical parametric oscillators, etc.). The electronically controlled, wide range of pulse energy, high peak power in a near TEM₀₀ mode characterizes the constructed laser. Due to energetic and spatial parameters, obtained in CW and Q-switched regimes, this laser can be used in the following disciplines: medicine, marking and material processing, laser metrology, range-finding, pointing and illuminating of targets, etc.

The paper describes the results of spectroscopic and generation investigations of SELG glasses with different concentrations of dopants for high-average power diode-pumped eye-safe microchip lasers. Transmission spectra of the laser glasses was measured and absorption coefficient calculated. The generation was carried out in two regimes: cw and quasi-cw. Up to 150mW of output power with slop efficiency 16% was achieved for cw generation and up to 300 mW of peak power with slop efficiency 19,4% for quasi-cw generation and duty-cycle 50%.

The results of spectroscopic and generation investigations of the concentrated Yb-Er laser glasses with different concentrations of dopants are presented. Absorption coefficient was calculated on the basis of measured transmission spectra of the laser glasses. Two regimes of the laser generation were investigated: cw and quasi-cw. Up to 180mW of output power with slop efficiency 18,5% for cw generation and up to 340 mW of peak power with slop efficiency 22 % for quasi-cw generation and duty-cycle 50% was achieved. The dependence of the output power on the temperature of the pumping diode and the active media were examined.

The paper presents the description and test results of the developed compact eye-safe laser head. As an laser material, rod made of athermal phosphate glass QX/Er by Kigre is used. The best results, including slope efficiency of 1.8% and threshold below 10 J, have been obtained for output mirror transmission of 10%, pump pulsewidth of 1.84 ms and repetition rate of 1 Hz. No significant thermal effects have been observed.

In this paper we demonstrate a successful recompression of 4.5 mJ, 30 fs femtosecond pulses from a Ti:Sapphire oscillator, amplified in a ring multi-pass optical parametric chirped pulse amplifier, using &bgr;-barium borate crystal pumped by a commercial frequency doubled Nd:YAG laser. Pulses with duration close to the Fourier transform limit were obtained. Numerical results of two stage high efficiency parametric amplifier are also presented.

In this paper, we present an analysis of light generation in various lasers based on photonic crystal structures. In our theoretical model, we take into account the gain saturation effect, transverse and longitudinal field distribution. That model allows defining in easy way the influence of the real structures parameters (for example photonic crystal cell geometry) on the normalized small signal gain, spontaneous emission, relaxation oscillation parameters, and 3dB modulation bandwidth.

Using semiclassical approach, we present numerical analysis of light generation in laser based on active, two-dimensional Photonic Crystal. Analysis of electromagnetic wave propagation and generation in active photonic structure is based on modified Real Space Transfer Matrix Method (RSTMM). As result we get output characteristics, describing behavior of output power versus real parameters of photonic structure.

In this work we present analysis and comparison of two basic operating schemes for praseodymium-doped up-conversion fiber laser. Single and double wavelength pumped systems were considered, taking into account pumping efficiency and pump power required for population inversion build-up. Time-dependent rate equation models have been developed for single and double doped systems, which allow detailed discussion and optimization of pumping parameters. Performed initial numerical simulations confirm usefulness of model for purposes of up-conversion fiber lasers analysis and design.

The paper presents investigation results of 1064 nm and 532 nm microchip lasers used for microinterferometer systems. Due to the developed designs, the output power of 10 mW and 8 mW of CW radiation at 1064 nm and 532 nm was obtained at the outputs of single-mode fibers, of core diameters of 6 &mgr;m and 3 &mgr;m, respectively. Spectral characteristics were examined and measurements of transverse distributions of laser beam were carried out. Using Michelson interferometer, optical beam quality was investigated as well as temporal and spatial coherences were determined. Mode structure of 1064 nm and 532 nm microchip lasers radiation were examined with Fabry-Perot interferometer. The obtained results proved wide range of possibilities of application of the designed microchip lasers in optoelectronic systems of measuring devices.

The paper provides a summary of the research work done at the Institute of Fluid Flow Machines devoted to problems of an active control of laser beam properties by applying an adaptive mirror in the high power industrial laser system. A deformable bimorph mirror with a shape controlled by a voltage supplied to the mirror electrodes was introduced to the laser system as a one of the resonator mirrors. Conditions for controlled modification of the spatial characteristics of the laser beam were determined in the experimental investigations of the influence of the intra cavity mirror deformations of spherical and aspherical axial symmetry on the modal performance of the high power cw CO₂ laser. Conditions for control of the laser beam focusing characteristics were investigated for the deformable mirror of varying curvature integrated into the laser beam delivery system.

The results of experimental tests concerning the wavefront sensor designed for control of the cw CO₂ laser beam transformed by the deformable multichannel bimorph mirror are presented in the paper. Wave-front curvature sensing is realised by measuring the radiation intensity distribution in the defocused beam and comparing it with the distribution recorded for a reference, undisturbed beam. The characteristics of the sensor are analysed versus the controlled deformation introduced to the tested beam by a deformable mirror. The experimental tests show that the curvature signal, measured by the designed array detector is proportional to the local distortions of the wavefront of the laser beam.

Establishing of a correlation between the ion laser output power and controlled losses introduced to a resonator allowed to determine basic parameters of the laser active medium i.e. unsaturated gain coefficient and gain saturation parameter. The resonator losses as well as optimum mirror transmission and were also determined. The tests were performed for ten Ar III and Kr III lines in UV spectrum.

In many applications of ion gas lasers the laser beam is used for specified short periods of time. For these applications laser systems are typically equipped with mechanical shutter. In consequence of this regime of laser beam modulation the peak output power of laser pulses are equal to constant output power generated by laser. Results of our experiments described in ¹ shows that in pulse mode of supplying discharge current it is possible to obtain significant increase of peak value of laser output power in comparison with laser output power generated in CW operation (without current modulation). In this paper we present results of our following experiments on pulse supply of ion laser filled with argon-krypton mixture. For this laser operates in pulse regime we have observed the significant - up to 3.5 times - increase of peak laser output power. This effect was especially strong in the UV range. This paper anwe measured in far field the sigxture percentage on the output power of individual Ar and Kr spectral lines in pulse operation. The research suggests that the most significant effect results from different gas pumping rate of the mixture components in the discharge path.a

In terms of maximal laser output power, the optimum gas pressure in the ion laser tubes depends on a wavelength of the generated spectral line. In order to control the gas pressure we introduced a simple and effective method of gas pumping from the laser tube to an additional reservoir. This method could be well employed in commercially available ion lasers.