Laser Amplification of Ultrashort Radiation Pulses of a SrMoO4 Raman Generator Operating on Dual Raman Modes

Hybrid master oscillator power amplifier laser systems have been proposed and experimentally implemented for laser amplification of ultrashort radiation pulses from a crystalline Raman generator operating in a highly transient regime on dual Raman modes with Stokes radiation wavelengths of 1. 06 and 1. 14 μm (frequency shifts 327 and 887 cm–1, respectively). Experimental optimization of laser amplification has been carried out when controlling both the chirp of the pump pulse of the Raman generator and the polarization of the amplified laser radiation. The ultrashort pulses of the SrMoO4 Raman generator with a wavelength of 1. 06 μm were amplified in a regime of small-signal gain up to output energy of 200 μJ with a pulse duration of 2. 2 ps in a system of two double-pass Nd3+: CaMoO4 crystal laser amplifiers (the amplification linewidth of 3 nm) with lamp pumping at the radiation polarization parallel to the Nd3+: CaMoO4 crystal optical axis. The adjustment of the rotation angle of the input radiation led, during the amplification, to the formation of double-wave radiation with wavelengths of 1061 and 1067 nm with each linewidth of 1. 7 nm at a frequency difference of 1. 6 THz, which is important for terahertz applications. The radiation of the same Raman generator with a wavelength of 1. 14 μm was amplified in a regime of saturated gain up to 200–250 μJ, which is close to the amplifier stored energy, in an ultra-wideband (160 nm) double-pass laser amplifier based on a F₂^ -: LiF crystal with nanosecond laser pumping at optimization of chirping the pump pulse of the Raman generator. For the Raman generator pumped with a transform-limited pulse (0. 25 ps), the spectrum width of the amplified radiation at 1. 14 μm was the widest: 52 nm with output energy of amplified radiation of 200 μJ and the pulse duration of 0. 8 ps with a compression capability of down to 40 fs.