Valeriy Badikov

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)

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.

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.

Difference-frequency generation of ultrashort pulses in the mid-IR using Yb-fiber pump systems and AgGaSe 2

We employ AgGaSe(2) for difference-frequency generation between signal and idler of synchronously-pumped picosecond / femtosecond OPOs at 80 / 53 MHz. Continuous tuning in the picosecond regime is achieved from 5 to 18 µm with average power of 140 mW at 6 µm. In the femtosecond regime the tunability extends from 5 to 17 µm with average power of 69 mW at 6 µm. Maximum single pulse energies of >1 nJ in both cases represent the highest values at such high repetition rates.

BaGa 4 S 7 : wide-bandgap phase-matchable nonlinear crystal for the mid-infrared

We report measurements of the transparency, nonlinear coefficients and damage threshold of BaGa4S7 grown by the Bridgman-Stockbarger technique. We also present calculations showing that this crystal is phase-matchable for down conversion into the mid-IR starting from a pump wavelength of 1064 nm.

PbIn 6 Te 10 : new nonlinear crystal for three-wave interactions with transmission extending from 1.7 to 25 µm

We have grown single crystals of PbIn6Te10, with clear transparency from 3 to 20 µm, and showed that this new nonlinear material possesses sufficient birefringence for phase-matching of three-wave parametric interactions and a nonlinear coefficient of 51 pm/V.

Phase-matched second-harmonic generation at 1064nm in quaternary crystals of silver thiogermanogallate

We demonstrate, for the first time to our knowledge, frequency doubling of 1064 nm radiation in sulphide crystals of Ag/sub x/Ga/sub x/Ge/sub 1-x/S/sub 2/ having engineerable birefringence and superior nonlinearity in comparison to oxide crystals.

Phase-matching directions and refined Sellmeier equations of the monoclinic acentric crystal BaGa 4 Se 7

We directly measured the phase-matching directions of second-harmonic and difference frequency generation in the principal planes of the biaxial BaGa4Se7 (BGSe) crystal using the sphere method. The simultaneous fit of the data allowed us to refine the Sellmeier equations of the three principal refractive indices of BGSe, and to calculate the tuning curves for infrared optical parametric generation.

Narrow bandwidth, picosecond, 1064 nm pumped optical parametric generator for the mid-IR based on HgGa 2 S 4

We report on optical parametric generation in a mercury thiogallate (HgGa2S4) crystal pumped by 16 ps, 1064 nm pulses at 250 kHz. A broad tuning range extending from 1.19 to 1.47 μm (signal) and from 3.85 to 10 μm (idler) is achieved. Narrow bandwidth, quasi-Fourier limited operation with high beam quality for the signal/idler pulses and >14% pump depletion is obtained by continuous wave seed injection at 1.29 μm.