M. Yu. Sharonov

Spectroscopic study of transparent forsterite nanocrystalline glass–ceramics doped with chromium

We present a spectroscopic study of transparent forsterite nanocrystalline glass–ceramic doped with chromium, a promising active medium for near-infrared fiber-optic applications. Absorption, emission, excited-state absorption spectra, and continuous function decay analysis of luminescence decay reveal the presence of Cr3+ and Cr4+ centers in both glass and crystal phases. The optical behavior of Cr3+ and Cr4+ centers is discussed and compared with that in bulk forsterite crystals.

Spectroscopic properties of nonstoichiometric multicomponent fluoride crystals with fluorite structure doped with Pr3+ ions

Abstract Spectral studies of nonstoichiometric multicomponent fluoride crystals, doped with the Pr 3+ ions, which have a CaF 2 -type partially disordered structure have shown that these crystals are promising candidates for amplifiers in the 1.3 μm range. In Ba 1− x R x F 2+ x :Pr crystals the oscillator strengths of all transitions are markedly increased in comparison with those in BaF 2 crystals due to the formation of centres with a low symmetry of their local environment. The concentration quenching of the luminescence in Ba 1− x R x F 2+ x :Pr and Pb 0.67 Cd 0.33 F 2 :Pr crystals as well as the probability of nonradiative relaxation from the 1 G 4 state are smaller than those in glasses.

Optical properties of neodymium activated crystalline nanostructures grown in transparent porous glass

Optical properties of neodymium self-activated nanocrystals grown in porous glass have been investigated. Mechanisms responsible for the opacity of pores glasses impregnated with solutions have been studied. Highly transparent glasses with nanocrystals grown in pores have been manufactured. Absorption, fluorescence, and fluorescence decay dynamic measurements were used to identify the phases grown in pores. We have shown that the major phase synthesized in the pores are crystal-like structures similar to that in bulk crystals. Optical properties of nanosize crystals differ from those in bulk single crystals because of specific size effects.

Direct diode-pumped laser operation of Cr 3+ - doped LiInGeO 4 crystals

Quasi-continuous wave (cw) laser action has been demonstrated by direct diode pumping of a new extremely broadband Cr(3+)-doped crystal. In contrast to previous works, where large-frame pump lasers have been employed, we have shown that low-power direct diode pumping of LiInGeO(4) is feasible, opening up the way for realizing compact and efficient laser sources for telecommunication applications.

Crystal growth and optical properties of Cr4+:Li2TiGeO5

Crystal growth and optical properties of Cr4+ centers in Li2TiGeO5 single crystals were investigated. Polarized absorption spectra at low and room temperature indicate a lowering of symmetry of the local environment of the Cr4+ ion from Td to C2 group of symmetry. The crystal field parameter Dq and the Racah paprameter B were determined to be Dq=930 cm−1, B=510 cm−1, and Dq/B=1.8. Emission spectra show wideband fluorescence from 1100 to 1600 nm with the maximum at 1200 nm. The lifetime of the metastable level decreases from 62 μs at 77 K to 6 μs at 300 K, indicating strong nonradiative quenching and a quantum efficiency of less than 10%.

Improved by Yb3+ sensitizer fluorite crystals, doped with Pr3+, for 1.3 μm optical amplifiers

Abstract The spectroscopic properties of Pr 3+ doped nonstoichiometric fluoride crystals with CaF 2 type of structure sensitized by Yb 3+ ions have been studied. It is a promising medium for 1.3 μm optical amplifiers. The comparison of line strengths calculated using the modified Judd-Ofelt and Kornienko et al. theories shows that a better agreement between experimental and calculated data is given by the latter theory. Using the experimental data on efficiency of energy transfer Yb→Pr optimal concentrations of the Pr 3+ and Yb 3+ ions and single pass gain coefficients have been calculated.

Optical properties of Cunyite (Cr4+: Ca2GeO4) crystals co-doped with Er3 ions

Abstract The optical properties of Cr4+ centers in Ca2GeO4 (Cunyite) single crystals co-doped with Er3+ ions have been measured. Excitation of Cr4+ produces both Cr4+ fluorescence centered at 1280 nm and Er3+ fluorescence centered at 1550 nm. The cross-section of the 4 I 13/2 – 4 I 15/2 Er 3+ transition is estimated using Judd–Ofelt analysis to be 8×10 −21 cm 2 . The quantum efficiency of the energy transfer from Cr4+ to Er3+ is obtained based on measurements of the decay of fluorescence from Cr4+. The relative populations and gain coefficients of Cr4+ and Er3+ centers under pumping in the Cr4+ band are calculated with varying Er3+ concentrations. The co-doped Cunyite (Ca2GeO4) crystal can be used as an active optical medium for 1200 to 1600 nm region.