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2Stimulated Raman scattering of broadband chirped Ti:sapphire laser pulse in calcium carbonate with Stokes seeded by narrowband nanosecond Nd:YAG laser pulse
V.I. Kovalev*, I.O. Kinyaevskiy, A.V. Koribut, Ya.V. Grudtsyn
P.N. Lebedev Physical Institute of the Russian Academy of Sciences, 53 Leninskiy Pr., 119991 Moscow, Russia
Stimulated Raman scattering (SRS) pumped by a broadband, compared to a bandwidth of material excitation, chirped 50-picosecond pulse with Stokes seeding by a 20-nanosecond narrowband pulse is experimentally and theoretically investigated. In experiment pulses generated by a femtosecond 0.95 ^m Ti:sapphire laser system and a Q-switched 1.064 ^m Nd:YAG laser were used for pumping and seeding SRS. An SRS-active CaCO3 crystal was used because of its Raman resonance frequency (~1089 cm-1 [1]) is nearest to the frequency difference of pump and seed radiation sources. It is shown that, despite a narrowband seed, the generated a Stokes pulse spectrum mimics the pump pulse spectral width promising a possibility for its recompression back to femtoseconds [2]. Achieved SRS conversion efficiency saturates at of 40% with a weak dependence on seeding pulse energy and on detuning of pump-seed frequency difference from the Raman resonance. Theoretical modeling confirms the observed effects and allows one to predict the characteristics of the investigated system on variation its parameters.
The demonstrated dual-frequency laser source will be used for mid-IR pulse generation at ~9.3 ^m wavelength by means of difference frequency generation in a nonlinear crystal, like in [3].
The research is supported by the Russian Science Foundation grant № 22-79-10068.
[1] P. Cerny, H. Jelinkova, P.G. Zverev, T.T. Basiev, Solid state lasers with Raman frequency conversion, Progr. in Quantum Electron., 28, 113-143 (2004).
[2] F.B. Grigsby, P. Dong, M.C. Downer, Chirped-pulse Raman amplification for two-color, high-intensity laser experiments, JOSA B, 25, 346-350 (2008).
[3] I.O. Kinyaevskiy, A.V. Koribut, L.V. Seleznev, Y.M. Klimachev, E.E. Dunaeva, A.A. Ionin, Frequency conversion of a chirped Ti:sapphire laser pulse to 11.4 ^m wavelength with SrMoO4 Raman shifter and LiGaS2 DFG crystal, Opt. Laser Technol., 169, 110035 (2024).
