Petr G. Zverev

Stimulated Raman scattering of picosecond pulses in barium nitrate crystals

Abstract Stimulated Raman Scattering (SRS) of picosecond pulses was investigated in Ba(NO3)2 crystals. The results are in good agreement with transient SRS theory. First and second Stokes conversion efficiencies were measured to be 25% and 5%, respectively.

Solid state laser with superbroadband or control generation spectrum

We report here on a novel Color Center Laser (CCL) optical construction, providing two unique regimes of generation: (a) a simultaneous generation across the whole emission region of the LiF:F2- active medium (1.1-1.24 micrometers ) with efficiency of 15% and a simultaneous frequency doubling in the visible green-red spectral region (0.55-0.62 micrometers ); (b) a regime of multi frequency lasing with a special preassigned spectral distribution or spectral coding by means of placing a special mask or image controller into the pump beam.

BaWO4 crystal for quasi-cw yellow Raman laser

The possibility to use BaWO4 solid state Raman laser for conversion of quasi-cw laser radiation has been demonstrated. The operation of yellow Raman laser with 1 kHz repetition rate and pulse width 10-600 ns under pumping with second harmonic of Nd3+:YLiF4 laser (527 nm) was investigated. The 1st Stokes (544 nm) and 2nd Stokes (583 nm) component radiation with promising characteristics was obtained at 1-10 W pump power.

Nd:BaWO4 Raman Laser

Raman laser was constructed on the base of new Nd:BaWO4 material Q-switched by LiF:F2- crystal. Emission at 1169 nm was obtained in 1.3 ns long pulse with energy 0.8 mJ.

Spatial-spectral transformation of laser radiation

This paper is focused on a design of flexible laser systems capable to provide spatial transformation of the pump radiation into the spectral domain of the output laser oscillation using specially designed “spatially dispersive” laser cavity. These systems also provide ultrabroadband or controlled spectral linewidth of the output laser oscillation. The theoretical analysis based on gaussian approximation for the designed laser cavities with “spatial dispersion” was used to provide maximum spatial resolution of the spatial-spectral transformation. The transformations of the spatial distribution of the pump radiation into the spectral domain of the output laser oscillation were experimentally demonstrated in the gain-switched LiF:F2+** and LiF:F2- lasers with total efficiencies of up to 20% and output pulse spectrum width wider than 140 nm, centered at 0.96 μm and 1.14 μm, correspondingly. As a result of the optimization of the angular dispersion of the output radiation, the simultaneous phase-matching for second harmonic generation in the single nonlinear crystal was realized for the whole oscillation spectral range. This technique allows to use a nonlinear frequency conversion for nonlinear transformation of the beam spatial distribution. Due to this, the ultra broadband (>100 nm) or multiline (20 lines) second harmonic and sum frequency oscillations were demonstrated in a LiIO3 nonlinear crystal with an overall efficiencies of up to 12%.

Raman Spectroscopic and Nonlinear Optical Properties of Barium Nitrate Crystal

The temperature dependences of a high frequency 1047 cm-1 Raman mode spectral broadening, picosecond temporal dynamics, resulting in the change of the SRS gain, and frequency shift is reported in barium nitrate crystal. Using a Z-scan technique the self-focusing of laser radiation in Ba(NO3)2 Raman crystal has been discovered and investigated under picosecond laser pulses.

All-solid-state, synchronously pumped, ultrafast BaWO4 Raman laser with long and short Raman shifts generating at 1180, 1225, and 1323 nm

A lot of attention is currently focused on synchronously pumped, extra-cavity crystalline Raman lasers generating one or two Stokes Raman components in KGW or diamond Raman-active crystals, and also generating additional components of stimulated polariton scattering in lithium niobate crystal having both cubic and quadratic nonlinearities. In this contribution we report on generation of more than two Stokes components of stimulated Raman scattering with different Raman shifts in the all-solid-state, synchronously pumped, extra-cavity Raman laser based on the Raman-active a-cut BaWO4 crystal excited by a mode-locked, 220 nJ, 36 ps, 150 MHz diode sidepumped Nd:GdVO4 laser generating at the wavelength of 1063 nm. Excitation by the pumping radiation polarized along the BaWO4 crystal optical axis resulted in the Raman generation with not only usual (925cm – 1), but also additional (332cm – 1) Raman shift. Besides the 1180-nm first and 1323 nm second Stokes components with the Raman shift of 925cm – 1 from the 1063nm fundamental laser wavelength, we have achieved generation of the additional 1227 nm Raman component with different Raman shift of 332cm – 1 from the 1180nm component. At the 1227 nm component the strongest 12-times pulse shortening from 36ps down to 3ps was obtained due to shorter dephasing time of this additional Raman line (3ps for the 332-cm – 1 line instead of 6.5ps for the 925cm – 1 line). It has to be also noted that the 1225 nm generation is intracavity pumped by the 1179 nm first Stokes component resulting in the strongest pulse shortening close to the 332cm -1 line dephasing time (3ps). Slope efficiency of three Stokes components generation exceeded 20%.

Eye-safe Nd :YVO{sub 4} laser with intracavity SRS in a BaWO{sub 4} crystal

A compact diode-pumped eye-safe Nd : YVO4 laser with an acousto-optic Q-switch and an intracavity BaWO4 Raman converter is developed. The laser power at a wavelength of 1536 nm with a pulse repetition rate of 20 kHz is 0.6 W, the diode-to-Stokes slope conversion efficiency reaches 44 %. Laser pulses with an energy of 35 μJ and a duration of 10 ns are achieved at a repetition rate of 15 kHz.

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.

Transformation of spatial domain of the pumping beam into spectral domain of the output oscillation

We present a novel technical approach to build a multiwavelength/superbroadband laser source based on a combination of spectral and spatial domains. This approach provides a direct transformation of spatial domain of the pumping beam into spectral domain of the output oscillation. Several spatially dispersive laser cavities were designed and studied both theoretically and experimentally for optimal spatial to spectral transformation. This spatial to spectral transformation was demonstrated for LiF:F2+** color center laser, single broad-stripe diode laser operating at 660nm and 1560 nm multi-stripe diode laser.