Aleksandr Ya Karasik

Direct amplification of picosecond pulses in F{sub 2}{sup -} : LiF crystals

An amplifier of picosecond pulses with an output power up to 1010 W and an energy up to 30 mJ at 1180 nm is developed on the basis of F2- : LiF colour-center crystals. A 3?5-ps, 0.03-mJ probe pulse at 1.18?m was obtained upon intracavity SRS conversion in a passively mode-locked Nd3+ : KGd(WO4)2 laser. The F2- : LiF crystals were pumped by 1053-nm nanosecond pulses from a Nd : YLF laser, amplified in a GLS-22 phosphate glass to an energy of 5 J. The probe SRS pulses were amplified in a four-crystal two-cascade amplifier based on F2- : LiF crystals with the total length of the active medium of 360 mm, by using counterpropagating pump beams. The dependences of the output radiation energy on the pump and input signal energies are measured.

One- and two-photon spectra of Nd{sup 3+} clusters in CaF{sub 2} and SrF{sub 2} crystals

The polarised two-photon (IR) and one-photon (visible) luminescence excitation spectra of Nd3+ nanoclusters in CaF2 and SrF2 crystals are measured at 10 K using a :LiF colour centre laser tunable in spectral ranges 1090 ? 1230 nm and 545 ? 615 nm with an emission linewidth of ~0.02 ? 0.03 cm-1, an average output power of ~55 mW, and a pulse repetition rate of 10 Hz. The two-photon excitation spectra at the 4I9/2 ? 4G5/2 transition reveal the structure, which is absent upon one-photon excitation, which can be explained by different selection rules for some Stark ? Stark transitions upon one- and two-photon absorption.

Stimulated Raman scattering of picosecond pulses in SrMoO{sub 4} and Ca{sub 3}(VO{sub 4}){sub 2} crystals

An express technique is proposed for the study of stimulated Raman scattering (SRS) in crystals excited by long trains of picosecond pulses. SRS was studied in several crystals excited by 15-ps pulses from an Nd{sup 3+}:CLNGG disordered garnet laser. SRS in SrMoO{sub 4} and Ca{sub 3}(VO{sub 4}){sub 2} crystals was obtained and investigated for the first time, and compared with SRS in popular SRS-active BaWO{sub 4} and KGd(WO{sub 4}){sub 2} crystals. (nonlinear optical phenomena)An express technique is proposed for the study of stimulated Raman scattering (SRS) in crystals excited by long trains of picosecond pulses. SRS was studied in several crystals excited by 15-ps pulses from an Nd3+:CLNGG disordered garnet laser. SRS in SrMoO4 and Ca3(VO4)2 crystals was obtained and investigated for the first time, and compared with SRS in popular SRS-active BaWO4 and KGd(WO4)2 crystals.

Stimulated four-photon mixing in glass fiber waveguides in the spectral range 0.4–1.8 μ

The Stokes—anti-Stokes components were generated in few-mode fiber waveguides pumped by a neodymium garnet laser (λp = 0.532 and 1.064 μ). Such generation was attributed to stimulated four-photon processes. Phase matching in the waveguides was achieved by compensation of the material dispersion with the intermode dispersion. The emission frequency could be varied by varying the diameter of the waveguide core. When the pump wavelength was λp = 1.064 μ, the generation of light in the Stokes region was observed at wavelengths λ right up to 1.8 μ, whereas in the anti-Stokes region this occurred right up to 0.4 μ.