Valery B. Sigachev

Spectroscopic and laser properties of Nd3+ doped fluoride crystals in 1.3-um region

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.

Growth and characterization of pure Cr; Cr,Er and Cr,Ho codoped Y2SiO5

The Czochralski crystal growth of pure Cr, Er and Ho doped as well as Cr,Er and Cr,Ho codoped yttrium silicate Y2SiO5 (YSO) is reported. The growth conditions for producing the inclusion free single crystals of high optical quality are discussed. Spectroscopic properties of the singly doped and codoped material at room temperature are compared. Energy transfer processes from Cr4+ ions to Ho3+ and Er3+ ions in YSO host have been demonstrated for the first time.

Passive Q-switching of 1.3-um Nd-lasers with Nd2+:SrF2 and V3+:YAG crystalline saturable absorbers and application to Raman shifting to the eye-safe region

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.

Investigation of Luminescent Properties of Sc:CaF2 and Sc,Ce:CAF2 Crystals as Promising New Media for UV Tunable Solid State Lasers

Wideband UV-visible luminescence under laser or CW lamp excitation was observed in γ-irradiated Sc and Sc-Ce doped CaF2 crystals: 1) at 380 nm in Sc:CaF2 and Sc:Ce:CaF2 crystals, attributed to Sc2+ ions and 2) at 300 nm in Sc,Ce:CaF2 crystals, due to Sc-Ce aggregate centers.

Efficient laser operation of Cr,Nd:GGG crystals at 1.331 and 1.423 um

Spectroscopic and laser properties of Cr,Nd:GGG and Nd:YAG crystals in the 1.3 - 1.45 micrometers wavelength range have been compared. Flashpumped Cr,Ce,Nd:GGG laser operating at 1.331 micrometers with total efficiency up to 3% and average output power of 65 W has been developed. For the first time to our knowledge oscillation at 1.4237 micrometers wavelength in Cr,Nd:GGG crystal have been obtained. Output energy of 2.3 J at this eyesafe wavelength with total efficiency of 1.23% have been obtained for flashpumped Cr,Ce,Nd:GGG laser in free-running mode. Average output power of 21.6 W at 13 Hz repetition rate have been achieved. Cr,Nd:GGG crystals advantages for 1.4 micrometers lasing compared to Nd:YAG crystals are discussed.

Large single crystals of neodymium and chromium co-doped gadolinium gallium garnet for efficient solid state lasers

The paper treats the problems of growth of large defectless single crystals of gadolinium- gallium garnet (GGG) doped with chromium, cerium, and neodymium, up to 65 mm in diameter and 130 mm long. The influence of UV radiation of the pump flashlamp on the formation of stable color centers in GGG-crystals co-doped with Cr, Ce, and Nd-ions was investigated. The processes of a nonradiative energy transfer from Cr to Nd ions in GGG were analyzed. The lasing properties of the GGG:Nd and GGG:Cr,Ce,Nd crystals were studied at 4F3/2 yields 4I11/2 and 4F3/2 yields 4I13/2 transitions. On the basis of grown crystals efficient lasers with the wavelengths of 1.06 and 1.33 micrometers are developed.