Synchronously-pumped, all-solid-state, picosecond Raman laser at 1169 and 1222 nm on single and combined Raman modes in a Ca3(VO4)2 crystal with 30-times pulse shortening down to 1.2 ps

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An all-solid-state extracavity synchronously pumped Ca3(VO4)2 Raman laser on broadened stretching (854 cm−1) and bending (354 cm−1) Raman modes with efficient stimulated Raman scattering (SRS) conversion at single frequency shift and the strongest 30-times pulse shortening down to 1.2 ps at combined frequency shift is demonstrated. The antireflection-coated, 78 mm long, a-cut Ca3(VO4)2 crystal was used as an active element under synchronous pumping by the 330 nJ, 1063 nm, 36 ps, 150 MHz mode-locked Nd:GdVO4 laser. SRS oscillation with slope efficiency of 34.2% and conversion of 18.5% at the wavelength of 1169 nm of the 854 cm−1-shifted first Stokes component with the pulse duration of 31 ps and output energy of up to 61 nJ in the external ring cavity with the output coupler reflectivity of 87% has been obtained. In the case of the second setup with high cavity Q-factor for the wavelength of 1169 nm, the additional cascade SRS component at 1222 nm with combined (854 cm−1 + 354 cm−1) frequency shift was observed. This component was generated with the slope efficiency of 8.1% and the output energy of 14.2 nJ with the output coupler reflectivity of 95%. Due to dynamics of SRS build-up in synchronously pumped extracavity Raman laser, the strongest pulse shortening at 1222 nm was achieved. The shortest pulse duration of 1.27 ps was measured at the cavity length detuning of +50 µm.