Sub-Nanosecond, High Peak Power Yb:YAG/Cr⁴⁺:YAG/YVO₄ Passively Q-Switched Raman Microchip Laser with the Emission of Multiple Pulses

This paper demonstrates the capability of sub-nanosecond, high peak power Yb:YAG/Cr4+:YAG/YVO4 passively Q-switched Raman microchip lasers at 1134 nm operated in multiple pulses mode under quasi-continuous-wave (QCW) pumping. Total pulse energy for the Stokes laser was 1.8 mJ with a 4 mm YVO4 crystal and TOC = 16%. The corresponding pulse repetition rate reached 225 kHz within a single pumping pulse. By employing a compact plane-concave cavity and 5 mm YVO4 crystal, the single pulse energy for the Raman laser was further scaled up to 44 μJ. The corresponding peak power was 95 kW. A highest output pulse repetition rate of 87.8 kHz and shortest pulse duration of 464 ps were found for the Raman laser. The results indicate that the Raman microchip laser configuration under QCW LD pumping is a promising approach for developing high peak power, commercial and portable Raman lasers with a pulse duration of several hundred-picoseconds at a pulse repetition rate of hundred kilohertz.