Vladimir Panyutin

Broadly tunable compact continuous-wave Cr 2+ :ZnS laser

We report the development of a continuous-wave, room-temperature Cr(2+) ZnS laser that is compact and tunable over 700 nm. The laser is pumped by a diode-pumped Er-fiber laser and generates 0.7 W of linearly polarized radiation at 2.35microm , at up to 40% slope efficiency. Cr(2+) ZnS directly diode-pumped at 1.6microm yields polarized radiation that is tunable over 400 nm at up to 25 mW of output power. A comparison of Cr(2+) ZnS with Cr ZnSe (70 mW, 350 nm) in a similar setup is given. As opposed to Cr ZnSe, the Cr ZnS laser is intrinsically polarized. Finally, we observe sensitization of the output radiation by a few milliwatts of the visible (470-500-nm) and near-infrared (740-770-nm) radiation.

Erbium fiber laser–pumped continuous-wave microchip Cr 2+ :ZnS and Cr 2+ :ZnSe lasers

Efficient continuous-wave (cw) lasing of Cr(2+):ZnS and Cr(2+):ZnSe crystals in external hemispherical cavities and in a microchip configuration under Er-fiber-laser pumping at room temperature are reported. The key result is what is believed to be the first successful demonstration of cw Cr(2+):ZnS and Cr(2+):ZnSe microchip lasers with maximum output powers of 63 and 100 mW at 2320 and 2520 nm, with slope efficiencies of 53% and 20%, respectively.

Efficient diode-pumped passively Q-switched laser operation around 1.9 μm and self-frequency Raman conversion of Tm-doped KY(WO4)2

Passively Q-switched operation of Yb,Tm:KY(WO4)2 and Tm:KY(WO4)2 lasers diode pumped at 805 nm has been investigated. A thin plate of Cr:ZnS was used as a saturable absorber for passive Q switching. A maximum average output power of 116 mW emitted at 1.9 μm in comparison to 160 mW for the free-running regime at the same pumping level has been obtained with a slope efficiency of 26% with respect to the incident pump power. Using a Tm:KYW sample with broadband antireflection coatings and dichroic laser resonator mirror, the first Stokes component of Raman self-frequency conversion was observed at 2365 nm.

Phase-matching properties of BaGa4S7 and BaGa4Se7: Wide-bandgap nonlinear crystals for the mid-infrared

Biaxial BaGa4S7 and BaGa4Se7 crystals transparent in the mid-IR have been grown by the Bridgman–Stockbarger technique in sufficiently large sizes and with good optical quality to measure the refractive indices and analyze phase-matching properties. (© 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Continuous-wave and Q-switched Tm-doped KY(WO 4 ) 2 planar waveguide laser at 1.84 µm

High-quality monoclinic planar waveguide crystals of Tm-doped KY(WO4)2 codoped with Gd3+ and Lu3+ were grown by liquid-phase epitaxy. For the first time, planar waveguide lasing was demonstrated in a monolithic cavity in the 2 µm spectral range. The laser was operated in the Q-switched mode using a Cr2+:ZnSe crystal as saturable absorber and in the continuous-wave regimes. The Q-switched planar waveguide laser delivered pulse energies up to 120 nJ at a repetition rate of 7 kHz.

Midinfrared optical parametric oscillator based on the wide-bandgap BaGa 4 S 7 nonlinear crystal

The orthorhombic biaxial crystal BaGa(4)S(7) has been employed in a 1064 nm pumped optical parametric oscillator generating <6 ns long idler pulses with energies as high as 0.5 mJ at 6.217 μm and average power of ~50 mW at 100 Hz. Notwithstanding the relatively low nonlinearity, ~3 times above threshold operation has been achieved at pump intensities more than 5 times below the crystal surface damage limit.

Optical properties of lithium indium selenide

Conditions of growth of LiInS2 and LiInSe2 crystals with high optical quality are studied. Data on the dispersion of refractive indices in red-phase LiInSe2 crystals are presented. Possible nonlinear three-frequency processes in LiInS2 and LiInSe2 crystals used for SHG and OPO are analyzed. Potentials of these crystals for application in OPO devices are shown.

Optical properties of thallium mercury iodide

We investigated the growth conditions and obtained Tl4HgI6 nonlinear crystals of red and black phases. We also measured the dispersion of the black-phase crystal refractive indices and analyzed possible nonlinear three-frequency processes.

Phase-matching and femtosecond difference-frequency generation in the quaternary semiconductor AgGaGe5Se12.

We present data on the linear (transmission, index of refraction) and nonlinear (second-order susceptibility) optical properties of the quaternary semiconductor AgGaGe5Se12 with orthorhombic symmetry--a solid solution in the AgxGaxGe1-xSe2 system with x = 0.17. The nonlinear coefficients are estimated from phase-matched second-harmonic generation near 3 microm. After numerical analysis of the phase-matching configurations for three-wave nonlinear interactions, the first experimental results on difference-frequency mixing, producing tunable (4-7.5-microm) femtosecond pulses at a 1-kHz repetition rate, are described. The pulses of only five optical cycles (FWHM = 84 fs) are generated near 5 microm with energy of 0.5 microJ. Because of its higher damage threshold, larger birefringence and bandgap, and greater variety of phase-matching schemes, AgGaGe5Se12 could become an alternative to AgGaS2 and AgGaSe2, more widely used in high-power and specific applications.

Angle noncritical phase-matched second-harmonic generation in the monoclinic crystal BaGa 4 Se 7

We performed a complete study of angle noncritical phase-matched second-harmonic generation in BaGa4Se7 in the mid-infrared region. We measured the dielectric frame orientation and showed that it does not rotate as a function of wavelength. We determined the phase-matching wavelengths and the associated spectral and angular acceptances along the x and y axes of the dielectric frame. We also estimated the magnitude of the nonlinear coefficients involved.