Asymmetric broadening and blue shift of the stimulated Raman scattering spectrum in water under chirped picosecond laser pulse train excitation

Abstract

For the first time, we have revealed an asymmetric broadening and a 35 cm−1 blue shift (up to 3400 cm−1) of the stimulated Raman scattering OH band in water under chirped picosecond pulse train excitation (pulse duration ∼60 ps with 8 ns interval between pulses) while increasing the train length to 25 pulses. From the observed broadening and shift of the OH band centroid, a lower estimate (≥8 ns) of molecular complexes spectral states relaxation time at room temperature was obtained.

Measurement of Multi-Stokes Ultrashort Pulse Shapes of Synchronously Pumped Stimulated Raman Scattering on Combined Vibrational Modes in a BaWO4 Crystal

“…The experimental setup of the synchronously pumped Raman laser with the system of measurement of the individual pulse shapes and relative temporal positions for the multi-Stokes output laser radiation is shown in Figure 1. The laboratory-designed master oscillator power amplifier Nd:YAP laser system, at a wavelength of λ0 = 1079 nm, was used as the pump laser (1) [18]. The pump laser master oscillator operated in a hybrid mode-locking regime with a passive negative feedback element based on a GaAs crystal [19] to form a long laser pulse train of ~200 pulses.…”

“…It also allowed obtaining equal durations of pulses of 7 ± 0.5 ps at a repetition period of 8 ns in the 56 pulses train. The laser pulse train was The laboratory-designed master oscillator power amplifier Nd:YAP laser system, at a wavelength of λ 0 = 1079 nm, was used as the pump laser (1) [18]. The pump laser master oscillator operated in a hybrid mode-locking regime with a passive negative feedback element based on a GaAs crystal [19] to form a long laser pulse train of ~200 pulses.…”