Transient stimulated Raman scattering (SRS) of 0.3 ps 515 nm laser pulses in B a W O 4 crystal was experimentally demonstrated with efficiency up to ∼ 20 % for the Stokes component with a wavenumber of ∼ 925 c m − 1 in a simple single-pass geometry. This anomalous high efficiency was obtained due to the laser pulse self-phase modulation resulting in spectral broadening and seeding the SRS. The applicability of seed pulse production for a high-pressure sub-picosecond C O 2 laser amplifier via difference frequency generation in L i G a S 2 crystal was numerically verified.

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.

PbIn₆Te₁₀ is a new mid-infrared (IR) nonlinear crystal with a very wide transparency range from 1.7 up to 31 μm. Calculated phase-matching angles show possibility of frequency conversion throughout the transparency range. Sum frequency generation of multiline carbon monoxide (CO) laser and difference frequency generation when mixing CO and carbon dioxide laser radiation were experimentally studied. Laser-induced damage threshold and frequency conversion efficiency under multiline CO laser pumping were measured.

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Spectral broadening of 0.3 ps 515 nm laser pulse in a highly Raman-active B a W O 4 crystal and fused silica demonstrates significantly different behavior with the incident pulse energy. While the broadening in fused silica is fairly symmetric with respect to the pump laser pulse wavelength, the Stokes wing broadening in the B a W O 4 crystal is 2 times wider than that of anti-Stokes wing, the former demonstrating a step-like increase with the pulse energy. To the best of our knowledge, the obtained data are the first clear evidences of the following facts: (i) stimulated Raman scattering with sufficiently high efficiency of conversion to Stokes components slows down spectral broadening induced by self-phase modulation, and (ii) the mechanism of Kerr nonlinearity, which is responsible for self-phase modulation in B a W O 4 , is of orientational nature. The nonlinear refraction coefficient and its decay time following from our experiments with B a W O 4 were estimated as n 2 ≈ 6.4. 10 − 15 c m 2 / W and τ N L ≈ 0.35 p s .