Alexander V. Shashkin

Magnesium- and zinc-aluminosilicate cobalt-doped glass ceramics as saturable absorbers for diode-pumped 1.3-μm laser

Q switching of a diode-pumped Nd3+:KGd(WO4)2 laser at 1.35 microm by use of cobalt-doped magnesium- and zinc-aluminosilicate glass ceramics as saturable absorbers is demonstrated. Q-switching efficiency up to 40% has been obtained. Ground-state absorption cross sections for Co2+ ions at the wavelengths of 1.35 and 1.54 microm are estimated to be (3.5-4.0) x 10(-19) cm2. Bleaching relaxation times under the excitation of the 4A2 --> 4T1(4F) transition of tetrahedrally coordinated Co2+ ions are of 280 +/- 50 ns and 700 +/- 80 ns for magnesium- and zinc-aluminosilicate glass ceramics, respectively.

Formation and Passive Q-Switch Performance of Glass-Ceramics Containing Co2+-Doped Spinel Nanocrystals

Compositions and heat treatment conditions were determined at which absorption and luminescence properties of aluminosilicate transparent glass-ceramics are defined mainly by tetrahedrally coordinated Co2+ ions located in spinel nanocrystals. Optical properties of cobaltdoped aluminosilicate transparent glass-ceramics have been studied in visible – near infrared (IR) spectral range. It was demonstrated that the concentration of tetrahedrally coordinated Co2+ ions in the spinel nanocrystals is determined by the CoO content in the initial glass and is independent of the heat-treatment schedule. Absorption saturation and bleaching relaxation under excitation of the 4A2→4T1(4F) transition of tetrahedrally coordinated Co2+ ions were studied. The value of groundstate and excited state absorption cross-sections of tetrahedrally coordinated Co2+ ions was estimated. Comparative study of output pulse parameters of Q-switched Er:glass laser using cobaltdoped glass-ceramics and Co2+:MgAl2O4 single crystal is presented.

Transparent Nd3+-Activated Glass-Ceramics in the Li2O–Al2O3–SiO2System: Physicochemical Aspects of Their Preparation and Optical Characteristics

The spectral–optical properties of transparent neodymium-activated lithium aluminosilicate glass-ceramics with titanium dioxide as a crystallization catalyst are investigated. The compositions of the initial glasses and the temperature–time schedules of heat treatment that provide a way of preparing highly homogeneous samples with low optical losses are determined. The most important parameters characterizing emission from the 4F3/2metastable state of neodymium ions are obtained by analyzing the optical spectra of rare-earth ions in terms of the Judd–Ofelt theory. It is shown that the introduction of phosphorus oxide into the composition of glass-ceramics leads to a considerable increase in the stimulated emission cross section for the basic 4F3/2–4I11/2transition, even though the rare-earth activator is not incorporated into the crystalline phase. It is found that acceptable quantum yields of fluorescence with the retention of a high heat resistance of glass-ceramics can be achieved by decreasing the volume fraction of the crystalline phase. The lasing testing of the materials prepared is performed in a setup with a lamp pumping. The low lasing parameters can be associated with the specific features in the optical properties of glass-ceramics, primarily, with the revealed depolarization of polarized light due to the presence of microstresses at interfaces.

Influence of reducing-oxidizing conditions on the optical properties of Co 2+ -doped magnesium aluminosilicate glass ceramics and their use as an effective saturable absorber Q switch

Nonlinear optical properties of Co(2+)-doped magnesium aluminosilicate glass ceramics prepared under normal and reducing conditions are studied in the range of the 4A2 --> 4T1(4F) transition of tetrahedral Co2+ ions. The results of passive Q switching of a 1.54-microm Er3+:glass laser with saturable absorbers made of Co(2+)-doped glass ceramics prepared at different conditions are presented. Q-switched pulses of 60 ns in duration and of 4.6 mJ in energy, corresponding to approximately 20% of the Q-switching conversion efficiency, are achieved.

The new SOO-U6 and SOO-I8 light-scattering glass-ceramics

This article presents the results of studies of the spectrophotometric characteristics of new glass-crystalline materials--light-scattering glass-ceramics. These materials are good simulators of an ideal diffuser and can be used to create comparison samples, photometric spheres, Lambertian attenuators, etc. in the spectral region from 0.3to2.4μm.

Stimulated emission of Co 2+ ions in transparent glass-ceramics

This paper investigates the differential absorption spectra of a number of transparent spinel-based cobalt-containing aluminosilicate glass-ceramics in the 550-700-nm range. A stimulated emission band accompanying transitions between the 4T1(4P) and 4A2 levels of the tetracoordinated Co2+ ion is detected in all the materials. Depending on the composition of the glass-ceramic, the effective stimulated-emission cross sections of the Co2+ ions at the maximum of this band are estimated at (4-5)×10−19 cm2.

Stimulated emission from co-doped zinc-aluminosilicate glass ceramics

Glass ceramic materials containing tetrahedral divalent cobalt ions have been recently introduced as laser saturable absorbers. Here we present study of stimulated emission from co-doped zinc-aluminosilicate glass ceramics (Co:ZAS).