Laser maskless patterning of magnetic thin films and transparent electrode films for microelectronics application has been performed to realize higher precision and higher rate processes than conventional techniques. Single crystalline ferrite and metallic alloy thin films such as FeAlSi, FeZrN, and CoZrNb have been etched without a mask in chemical solutions to realize magnetic head gap structures for future applications. Indium tin oxide (ITO) thin films on a glass substrate have been etched by laser ablation to provide a maskless patterning process for flat panel display (FPD) fabrication. Laser cleaning has been applied to a magnetic head slider and glass substrates as an alternative technique to conventional wet cleaning processes.

Principles and ultimate potentialities of laser diagnostics are expanded for absorption systems taking photodesorption of alkali metal atoms from a surface of transparent dielectrics and photoevaporation of metal surface as an example. A possibility is shown to record extra-low atomic fluxes, time-of-flight spectra of desorbed atoms, surface atoms' concentration at a sub- monolayer coating, adsorption energies and sticking coefficients of atoms impacting the surface, as well as processes of atoms' surface diffusion and their condensation on the surface. Feasibilities of using laser diagnostics for molecular systems' studies are discussed.

We consider creation of surface nanostructures by using two different laser near-field configurations. One configuration arising in the course of diffraction of a plane laser light wave by an aperture of a small size (less than the optical wavelength) causes a normally incident atomic beam to undergo deep focusing to a size 10 angstroms. The second configuration is the evanescent fields of two laser beams experiencing total internal reflection at dielectric-vacuum interface. This configuration can produce a surface trap for neutral atoms permitting it to deposit a single atom on a surface.

Pulsed-laser irradiation on a solid surface induces a highly efficient surface cleaning of submicron-sized particulates and undesirable organic overcoat films. The nanosecond-pulsed UV laser irradiation, shortly after the deposition of a thin liquid film on the surface, induces rapid vaporization of the liquid film and removal of particulates (`steam cleaning'). The laser beam also causes ablative photodecomposition of organic film contaminants on the surface (`dry cleaning'). A laser cleaning tool is constructed with an aim toward practical use based on an industrial grade KrF excimer laser. The tool includes a computer-controlled laser beam scanning system and a stable liquid film deposition unit, providing a cleaning rate of over 200 cm²/min. The cleaning strategy and the physical mechanisms of the laser cleaning techniques are also studied.

The transient temperature and pressure field development in the excimer laser-induced vaporization of liquids in contact with a solid surface is studied. A thin silicon film, which has temperature-dependent optical properties, is embedded between an absorbing chromium film and a transparent fused quartz substrate. Static reflectivity measurement is performed to determine the thin film optical properties at elevated temperatures. The transient backward reflectance responses from the silicon layer are compared with heat transfer modeling results. The backward reflectance probe is not affected by the creation of bubbles and is successfully employed for the first time to measure non-intrusively the temperature development during the rapid vaporization process. The optical reflectance probes are applied from the front-side and back-side of the sample simultaneously to monitor the dynamic bubble nucleation behavior and transient temperature development, respectively, at various ambient pressures using a high- pressure cell. The investigation on the effect of ambient pressure on the bubble nucleation threshold combined with the surface temperature measurement determines the thermodynamic state of the superheated metastable liquid at the interface and subsequently the explosion pressure.

The formation of bubbles at a liquid-solid interface due to acoustic cavitation depends particularly on the preconditions of the interface. Here, it is shown that following laser- induced bubble formation at the interface the acoustic cavitation efficiency is strongly enhanced. Optical reflectance measurements reveal that this observed enhancement of acoustic cavitation due to preceding laser-induced bubble formation, which could be termed as a memory effect, decays in a few hundred microseconds. By performing a double-pulse experiment using two excimer lasers the influence of process parameters, such as liquid temperature and salt concentration, on the temporal decay of the memory effect has been studied. An analysis of the experimental results by a diffusion model is presented.

Combined thermally induced etching and deposition of W in a mixture of WF₆ and H₂ is investigated by local laser-induced patterning of thin tungsten layers on quartz. The process divides into areas of pure etching and deposition, depending on the partial pressures of the gases.

Boron nitride (BN) films were deposited on (001) faces of silicon (Si) using pulsed excimer laser ablation at 308 nm and 248 nm. The films were analyzed by Fourier-transform-infrared (FTIR) transmission spectroscopy, x-ray photoelectron-spectroscopy (XPS) and by x-ray diffractometry (XRD). The films are boron rich and contain hexagonal BN (h-BN). They are x-ray amorphous. So far we found no evidence for the formation of cubic BN (c-BN) crystallites in the films.

A new method of diamond-like film deposition using laser-initiated discharge of benzol vapor is described. The investigation of the discharge parameters was carried out. Dependence of these parameters on characteristics of laser radiation, electric field, and vapor pressure was obtained. It has been shown that this method allows us to produce the coatings with low optical absorption.

Diamond-like films were produced by laser ablation of glass-carbon target in the presence of residual gas (Ar) in a reaction chamber. It appears that the band gap value of the films deposited in this case is more than 20% greater than that of the films deposited at high vacuum. This influence of a gas on optical properties of the produced coatings was explained in the framework of a simple mechanical model.

Samples of silica glasses of approximately 1 cm³ scale were synthesized with 100 W cw CO₂ laser torch on the target surface of silica materials in oxide, neutral and reductive atmospheres. Fused quartz glass, silica glasses synthesized by SiCl₄ + H₂ + O₂ flame hydrolysis and in SiCl₄ + O₂ plasma and Ge-doped glass were used as starting materials. Oxygen deficient center concentrations of approximately 10¹⁶ cm^-3 were registered in samples synthesized in neutral and reductive conditions by optical absorption and luminescence spectroscopy. Transformations of spectra in dependence on Ge concentration confirm that the spectra are characteristic of oxygen deficient equals Si: and equals Ge: point defects.

Thin films of biocompatible materials such as hydroxylapatite (HA) - Ca₁₀ (PO₄)₆(OH)₂ were deposited by laser ablation technique. The films of HA were created on Ti substrates by KrF laser. The layers were deposited in vacuum, in pure H₂O vapors (pressure 2 X 10^-3 mbar - 2 X 10^-1 mbar), and in Ar/H₂O vapor mixture. Influence of laser energy density E_T (3 Jcm^-2, 13 Jcm^-2) and substrate temperature T_g (500 degree(s)C - 760 degree(s)C) on the film parameters was studied. Two different technological processes were used for HA target preparation. Films and targets were characterized by Rutherford backscattering analysis (RBS), particle induced x-ray emission (PIXE), x-ray diffraction (XRD), scanning electron microscopy (SEM) and by Knoop microhardness and scratch test. The best crystalline HA films were reached in the mixture of Ar/H₂O. Higher T_g had to be used for such deposition. Higher T_g was also preferable from the point of film microhardness. Adhesion of films to the substrates in the range of tens of Newtons was measured. The preliminary results of in vitro experiments of films biotolerance and resorbability are also presented.

Ferroelectric thin film of Pb(Zr_0.48Ti_0.52)O₃ (PZT) was deposited on lattice mismatched (0001)sapphire for substrate temperatures T_g in the region from 470 to 590 degree(s)C and oxygen pressure of 200 and 900 mTorr. Structural properties were characterized by XRD. Improvement of XRD patterns of deposited films with post-annealing temperature of the furnace was studied. The development of the plasma plume shape from PZT target under changing deposition conditions was investigated by CCD camera. Results show strong dependence of plume shape with oxygen pressure and laser beam spot size.

Deposition of thin Polytetrafluorethylene (PTFE) film by laser ablation deposition (LAD) technique is briefly described. The method utilization, transport conditions, and optimal setup are presented. The paper also deals with the methods of prepared thin films characterization (scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy) and comments on all data achieved from all characterization measurements.

The contribution deals with the results of our work on ohmic contact formation, the process optimization. The contacts should be optimized with respect to chemical composition of metallization, energy density of laser radiation, and repetition rate of laser pulses. These contacts also enable us to interconnect the surface of the samples with a very thin layer under the surface ((delta) -doped layer).

The authors of the report developed the method of modifying the surface of ceramic Y-Ba-Cu by laser irradiation. This method permits us to obtain ceramic superconducting structures on the surface with T_c equals 88 +/- 1 K, (Delta) T equals 1.4 +/- 0.1 K, I_c >= 10⁴ A/cm². Such structures are the films 5 - 10 micrometers thick on the ceramic Y- Ba-Cu which are in the non-superconducted state.

We investigate dynamic resistance (dV/dI) of high-Tc superconducting thin films and tunnel junction after laser radiation processing. The films of YBaCuO were prepared by laser and magnetron ablation on Al₂O₃ substrates. The tunnel junctions were made by fine silver wires attached to the processing surfaces. The resistance (dV/dI) was determined by a four-probe measurement. The YAG laser operating in Q-switched mode was used to interact with superconductors. The anomaly is observed in the current-voltage curve of the junction after radiation interaction. We observe hysteresis in the shape of V(I) curve. These effects are not observed without laser radiation interaction and in this case the behavior of tunnel junction is described for the standard BCS theory.

The results of the study of electrostimulated diffusion in polycrystalline and epitaxial YBCO (123) and ceramic Bi (2223) HTCS films give evidence of the motion of heavy ions and oxygen under the transport superconducting current flow. Long-duration dc flowing in films in the superconducting state at 4.2 and 77 K leads to new morphological forms with modified chemical composition and formation of nonsuperconducting phases. The effect in the high- quality epitaxial films exits, but it is weaker. Long-duration flowing of high-power 36 GHz current leads to formation of periodic strip structures enriched with copper and oxygen. The experiments with thick (25 micrometers ) Bi (2223) films reveal modified stoichiometry practically over the entire film. At 300 K the YBCO (123) system is shown to have the ionic conduction component. Possible mechanisms of the observed experimental effects are discussed.

Laser processing has become a powerful tool for surface or bulk modifications and is applied successfully in many areas. The use of laser in technology depends on the knowledge of the physics of the processes that occur on interaction between laser radiation and matter. To optimize laser material processing an effective diagnostic method should be developed. Strong light scattering is very typical for laser processing, so measured parameters of scattered light bring information of the process, including velocity field. That opens the way to developing laser physic methods for non-destructive diagnostics and on-line control. The main idea of our measurements is by irradiating the surface of strongly absorbing condensed matter with the intense coherent radiation one can on the one hand induce such phase transitions as thermocapillary convection and evaporation and on the other hand form and observe the Doppler shift in the frequency of radiation backscattered from scatterers within the irradiated volume and consequently measure the velocity of laser induced near-surface hydrodynamic processes.

Studying of picularities of laser beam interaction with different materials remains an actual problem in spite of large a mount of investigations being carried out during more than thirty-year period since first industrial lasers have app.i red . It is connected with number of reasons, such as insufficiency of detailed information about physical al)d phyeo-chemical processes occuring in the zone of ias iniiuence, as well as about mechanisms, which are responcihle for foriiiing of definite. structure and chemical composition of surface layers under laser processing of materia1. The most developed is computer simulation of thermal processes. In spite of essential non-linearity ( thermoonductivity and heat capacity depend on temperature) of mathematical models of laser heating, there are exampleS of successful application of computer simulation.

The kinetic Ising model with competing dynamics is expected to reflect main qualitative features of the phase equillibria in the presence of irradiation. This model was extensively investigated by Martin, Bellon and others with the use of the Kubo anzatz as well as by direct computer simulation. Nevertheless, some fundamental questions concerned with the nature of the steady state in this model seem to be unresolved. That is why the general formulation of the statistical thermodynamics for the model, based on the microscopic approach, seems to be interesting and promising.

The interaction changes between three molecules in trimers due to excitation presence are calculated. The consideration did not take into account the resonant quanta degradation processes (heating). In the frame of two-level approximation the strengthenings of dimers and trimers were found. In case of gas this effect can lead to balance shift. If resonant molecules are on a surface, the clusters strengthening because of quantum exchange may be regarded as the adsorption potential deepening.

The interest in solid-state lasers has been renewed in the last decade. Diode-laser pumping, tunable lasers, and nonlinear optics are the main developing technologies to have revitalized the field of solid-state lasers. An overview of the more recent results in rare-earth and transition-metal doped systems is made in addition with the advances in frequency conversion by means of optical parametric oscillators.

Barium nitrate Raman laser pumped with nanosecond YAG:Nd laser is investigated. High energy conversion efficiencies to the first, second, and third Stokes components up to 60%, 35%, and 25%, respectively, are obtained. Results on development of Raman laser for the eye safe spectral region are presented.

Passive Q-switching of 1.3 micrometers neodymium lasers with Nd²⁺:SrF₂ and V³⁺:YAG crystalline saturable absorbers are studied. Giant pulses up to 5 mJ energy and 40 ns duration were obtained. Efficient Raman shifting of the 1.3 micrometers pulses of passively Q-switched lasers to 1.55 micrometers wavelength are realized in Ba(NO₃)₂ crystal.

For a number of neodymium doped fluoride crystals both with regular and disordered structure the Judd-Ofelt analysis of absorption spectra have been performed, and fluorescence and lasing spectra were studied in order to reveal the most promising materials for optical amplification in a 1.3 micrometers telecommunication window. The most suitable crystalline media investigated was found to be cubic disordered fluorides based on (50 - 70%) SrF₂ - (50 - 30%) CaF₂ solid solutions with Nd³⁺ optical centers having tetragonal local symmetry. These crystals have (1) low value of excited state absorption line strength, (2) high metastable level lifetime (1.2 - 1.3 ms), (3) high enough emission cross section for fluorescence (approximately 4 X 10^-21 cm²), and (4) proper fluorescence peak at about 1310 nm wavelength and comparatively wide fluorescence band with about 20 nm FWHM.

In this paper we report our investigation of mode-locked and Q-switched regime in Cr⁴⁺:Y₃Al₅O₁₂ laser with synchronous pumping by Nd:YAG laser. We have obtained mode-locked generation of tunable radiation in the range from 1,350 to 1,500 nm. In our investigation we have found position in the stability area where the laser operates on mode-locked or Q-switch regime. In the edge of stability we observe a Q-switch regime of laser operation with rectangular output pulses. We have analyzed the properties of the main optical elements in our laser systems to find out to which extent these elements could be considered as temporal Gaussian systems, and simulated on a computer the ultra-short pulse evolution in the laser resonator for the investigation of the structure of the transformation phase space. The presence of aberration being a source of the ultra-short pulses distortion could drastically complicate a phenomenon.

Infrared-to-visible up-conversion processes can be very important in device applications. Numerous investigators have evaluated various materials for device potential. The limiting factor is the efficiency of the process. The efficiency depends on many factors with the most important ones being energy transfer and multiphonon transitions.

Optical properties with more than 120 multicomponent nonstoichiometric fluoride crystals M^+,2+F_m-R³⁺F_n with CaF₂ structure doped with Nd³⁺ and Pr³⁺ were studied especially in 1.3 micrometers spectral range which is promising for operation in the second telecommunication window. The direct measurements of excited state absorption and single pass gain in 1.3 micrometers range have been carried out for Na_0.4Y_0.6F_2.2 and Ca_0.9Y_0.1F_2.1 crystals. The effective cross-sections and halfwidth of gain band have been determined ((sigma) _max equals 2.2 +/- 0.7 10^-21 cm², (Delta) equals 40 cm^-1 and (sigma) _max equals 4.5 +/- 0.9 10^-21 cm², (delta) equals 60 cm^-1, respectively). The line's strengths in Ba_1-xGd_xF_2+x:Pr crystals has been found to be raised in nonstoichiometric crystals in comparison with stoichiometric ones due to formation of another type of optical centers. The energy of destruction of these Pr³⁺ positions has been determined to be 280 cm^-1. The mean decay rate of Yb³⁺ is found to be proportional to the multiplying of Yb³⁺ and Pr³⁺ concentrations in Yb³⁺ sensibilized BaGdF:Yb,Pr and PbCdF:Yb,Pr crystals. The optimal concentrations of Yb and Pr and single pass gain coefficient have been calculated.

Possibilities of the excited state absorption (ESA) spectroscopy as the method of investigation of charge transfer (ChT) process in doped ionic crystals are discussed. Temperature dependence of ChT bands of the Cr³⁺ ions doped crystals suggests that ChT process is mainly donor nature, e.g. [(3d yields 4s or 3d yields (ligand orbital)]. ChT bands positions of Ti³⁺:Al₂O₃ and Cr³⁺:Li₂Ge₇O₁₅ crystals measured by ESA spectroscopy and two-step photoionization method are approximately the same for each crystal. Wide-band gain of Cr³⁺:LGO crystal is overlapped by strong ESA band preventing laser effect in the whole luminescence range.

Recent data on the excited state absorption (ESA) in the glasses doped with Nd³⁺, Er³⁺, Pr³⁺ is reviewed. In particular, the data on Russian commercial laser glasses are presented. The different techniques applied to obtain ESA data are analyzed and classified into two groups: (1) the methods using indirect measurements and based on the results of approximate theories, (2) the methods using direct spectral measurements of the pumped samples. The possibilities of predictions of glass composition effect on the ESA are considered.

In this paper we report about the growing and laser operation of Nd:GdVO₄. From a technological point of view this material has a number of advantages, which open the possibility for the growth of this large size crystal for mass production. In the last few years a handful of neodymium-doped vanadium-based crystals have been identified as potential successors to Nd:YAG. These crystals include yttrium orthovanadate (YVO₄), gadolinium orthovanadate, (GdVO₄) and strontium fluorovanadate (SVAP or Sr₅(VO₄)₃F). All are promising substitutes for Nd:YAG in diode-pumped laser products. The laser cross section for the vanadate crystals range from 1.8 to 5.6 times greater than ND:YAG. They also maintain a strong singleline emission with nearly the same peak wavelength as Nd:YAG. The vanadate crystals are uniaxial, producing only polarized laser output, thus undesirable thermally induced birefringence. In addition, the peak pump wavelength for all crystals is 808 nm, the standard wavelength of currently manufactured high power diodes for laser pumping. Broad pump bandwidths of Nd³⁺ ions in vanadate laser materials mean more efficient pumping operation at a wider range of temperatures and a range of diode specifications, resulting in a less-expensive product. For the first time in work at Moscow General Physics Institute (GPI) and the Institute of Laser Physics (Hamburg, Germany) Nd:GdVO₄ was examined in a diode-pumped laser.