Anna V. Shaiduko

Cascaded carbon monoxide laser frequency conversion into the 4.3–4.9 μm range in a single ZnGeP 2 crystal

Collinear cascaded mid-IR frequency conversion in a single nonlinear optical crystal was accomplished. Concurrent collinear generation of the sum frequency of multiline fundamental band carbon monoxide laser radiation as a first frequency conversion cascade resulted in collinear difference frequency generation within the 4.3 to 4.9 μm spectral range when mixing this sum frequency radiation with the fundamental one as the second cascade in the same ZnGeP(2) nonlinear optical crystal.

Limiting pump intensity for sulfur-doped gallium selenide crystals

High optical quality undoped and sulfur-doped gallium selenide crystals were grown from melts by the modified vertical Bridgman method. Detailed study of the damage produced under femtosecond pulse exposure has shown that evaluation of the damage threshold by visual control is unfounded. Black matter spots produced on crystal surfaces do not noticeably decrease either its transparency or its frequency conversion efficiency as opposed to real damage identified as caked well-cohesive gallium structures. For the first time it was demonstrated that optimally sulfur-doped gallium selenide crystal possesses the highest resistivity to optical emission (about four times higher in comparison with undoped gallium selenide).

Model and experimental investigation of frequency conversion in AgGaGexS2(1 + x) (x = 0, 1) crystals

Analysis of available and developed data on phase matching in AgGaGexS2(1 + x) (x = 0, 1) crystals is carried out. Nanosecond AgGaS2 type I optical parametric oscillator with a continuously tunable range 2.65–5.29 µm is demonstrated pumped by a Q-switched Nd : YAG laser. An output pulse energy of up to 0.56 mJ at 4 µm is recorded. Phase matching of second harmonic generation in both crystals is represented. Best sets of Sellmeier equations for two crystals are determined.

Optimal doping of GaSe with isovalent elements

The сentimeter-sized GaSe crystals doped with 0.01, 0.05, 0.1, 0.2, 0.5, 1, 2 at.% of Al and 0.025, 0.1, 0.5, 1,2 at. % of Er have been grown by the modified Bridgman method with heat field rotation. The crystals have been studied in comparison with GaSe crystals doped with 0.1, 0.5, 1, 2, 3, 5, 7, 10.2 wt.% of S, 0.01, 0.1, 0.5, 1, 2, 3, 5 wt.% of In and 0.01, 0.1, 0.5, 1, 2 wt. % of Te grown by the conventional Bridgman method. The distribution coefficient of Al in the grown GaSe:Al (≥0.1 at.%) crystals has been estimated to be ∼8⋅10-3 and it is within the range of 10-2-10-3 in Er-doped crystals. For the first time, the optimal doping levels have been estimated for Al and Er in GaSe as 0.01- 0.05 at.% for Al and ~ 0.5 wt.% for Er, respectively.

Sellmeier equations for LiInS2 and LiInSe2

Disperse properties of biaxial mixed LiIn(Se1-xSx)2, x= 0;0.5; 1, nonlinear crystals are investigated. Most useful Sellmeier equations for parent LiInS2, LiInSe2 and mixed LiIn(Se0.5S0.5)2 crystals are identified from available and original results on disperse properties and experimental phase matiching angles for second harmonic generation. Modernized Sellmeier equations are proposed for parent crystals.

GaSe damage threshold under IR pulse pumping

Damage threshold of non-linear GaSe crystals under IR fs (Ti:Sapphiere 800 nm laser and 1.1-2.9μm OPG) and ns (2. 79 Er3+:YSGG and 10.6μm CO2 laser) pulse pumping is studded in details. Local micro defects and field induced effects (GaSe dissociation, multiphoton absorptions and transient transparency origin effects) are identified as responsible for damage threshold in this case. Local (including nano scaled) defects and thermal effects are identified as reason of damage threshold under ns pulse pumping.