Vyacheslav V. Osiko

Room-temperature color center lasers

A survey of results is presented on the development of room-temperature tunable lasers using color centers in ionic crystals and on using color center crystals as nonlinear filters and passive Q switches for neodymium lasers. >

Efficient laser based on CaF 2 -SrF 2 -YbF 3 nanoceramics

CaF(2)-SrF(2)-YbF(3) fluoride ceramics of high optical quality was prepared, and its absorption, fluorescence, and laser oscillation properties were investigated. Oscillation slope efficiency that was only a few percent lower than that for a single crystal of similar composition was demonstrated under diode pumping.

Disordered garnets Ca3(Nb, Ga)5O12:Nd3+ : prospective crystals for powerful ultrashort-pulse generation

Disordered garnets Ca3(Nb, Ca)5O12:Nd3+ grown by the Czochralski method are used in a pulsed picosecond laser to generate 5–10-ps pulses in passive mode-locking trains of 120–180 ns and 1.6 mJ of energy at 1.06 μm. The evolution of the pulse parameters along the train is investigated. Direct time-resolved measurements allow us to determine the positive linear chirp of the laser frequency, which causes the pulse spectral broadening of Δν = 50–60 cm−1. The chirped pulses are compressed in the external grating compressor. The measured pulse duration of 2 ps is limited by the time resolution of the streak camera.

Oriented attachment of particles: 100 years of investigations of non-classical crystal growth

The results of investigations of non-classical crystal growth by the oriented attachment mechanism are summarized. The data published since the end of the 19th century are considered, the attention being focused on analysis of publications of the last 15 years. Data on characteristic features of the oriented attachment of particles are described systematically. The experimental methods used to elucidate the peculiarities of non-classical crystal growth, including in situ methods, are discussed. The prospects of application of the oriented attachment of particles for the formation of various materials are demonstrated.The bibliography includes 227 references.

SrF2:Nd3+ laser fluoride ceramics

SrF(2):Nd(3+) fluoride ceramics of high optical quality was prepared and its spectroscopic and laser properties investigated. Oscillations of different optical centers depending on the excitation wavelength were obtained with a slope efficiency of up to 19%.

Laser and self-Raman-laser oscillations of PbMoO 4 :Nd 3+ crystal under laser diode pumping

Different regimes of laser operation and stimulated Raman scattering (SRS) for a laser diode (LD)-pumped PbMoO4:Nd3+ crystal have been investigated. Under 1.5 W LD pumping, the output power of the PbMoO4:Nd3+ laser in the free-running mode at 1056 nm reached 0.65 W with a slope efficiency of up to 53%. Using different LiF: F-2 saturable absorbers, we achieved a maximum pulse energy of 11 microJ at a 1.4 ns pulse duration and a maximum output power of 0.35 W (10 microJ) at a 7 ns pulse width in the passively Q-switched mode. PbMoO4:Nd3+ self-Raman-laser operation at 1163 nm (first Stokes) was obtained for the first time, to our knowledge. The self-Raman-laser output pulse energy was measured to be as high as 6 microJ and the pulse duration was estimated to be shorter than 500 ps.

Diode-pumped Er:CaF 2 ceramic 2.7 μm tunable laser

Spectroscopic and laser properties of a newly developed high optical quality Er:CaF2 hot-formed ceramic were investigated. Under pulsed 968 nm laser diode pumping, the mid-infrared (2.7 μm) radiation was obtained with a slope efficiency of 3%. Laser tunability was reached using a birefringent filter and the laser tuning range of 118 nm, from 2687 up to 2805 nm, was demonstrated. The maximal output energy reached was 0.48 mJ at 2730 nm for the absorbed pumping energy 34 mJ.

Study of the boron-oxygen units in crystalline and molten barium metaborate by high temperature Raman spectroscopy

Abstract The vibrational spectra of the boron-oxygen structural elements in single crystal β-BaB2O4 and BaB2O4 melts were studied by high temperature Raman spectral analysis. The experimental Raman peaks were assigned to the calculated normal vibrational modes of the free [B3O6] molecular unit. The observed vibrational mode splittings were found to be consistent with C63v symmetry for β-BaB2O4. Experimental vibrational spectra were compared with those of LiBO2 and CsBO2 in order to determine the temperature-dependent populations of chain, ring, and tetrahedral structural elements in the respective melts, and these in turn were shown to correlate with the degree of melt supercooling required for spontaneous crystallization to occur.

Preparation of nanopowdered M1−x R x F2+x (M = Ca, Sr, Ba; R = Ce, Nd, Er, Yb) Solid Solutions

The synthesis procedure has been worked out, and nanopowders of fluoride solid solutions (ss) Ca1−xRxF2+x (R = Er, Yb), Sr1−xNdxF2+x, and Ba1−xCexF2+x have been manufactured by coprecipitation from aqueous solutions. The powders consist of rounded particles with sizes from 50 to 150 nm. The particles with sizes of about 150 nm are aggregates of adhered nanoparticles. The nanoparticles are highly reactive and sinter at low temperatures (T < 0.35Tm).

Synthesis of Refractory Materials by Skull Melting Technique

This chapter discusses methods of growing refractory oxide single crystals and synthesis of refractory glasses by skull melting technique in a cold crucible. It shows the advantages of radiofrequency (RF) heating of dielectric materials in a cold crucible and points out some specific problems regarding the process of growing crystals by directional crystallization from the melt and by pulling on a seed from the melt. The distinctive features of the method of directional crystallization from the melt are discussed in detail on the example of technology of materials based on zirconia, i.e., cubic single crystals and partly stabilized single crystals. It is shown that the size and quality of crystals are functions of the process conditions, such as thermal conditions under crystallization, growth rate, and chemical composition. We provide an overview of research on the structure, phase composition, and physicochemical properties of crystals based on zirconia. The optical, mechanical, and electric properties of these crystals make them suitable for a number of technical and industrial applications in optics, electronics, materials processing, and medicine. In this chapter, we also consider some problems regarding the synthesis of refractory glasses by skull melting technique. The physicochemical and optical properties of glasses are given and their practical applications in technology are discussed. We note that one of the better developed and most promising applications of skull melting technique is the immobilization of liquid and solid waste (also radioactive waste) into solid-state materials by vitrification.