Acousto-optically Q-switched Nd:YLF/KGW/LBO Raman yellow laser operating at 578 nm.

Abstract

A high-power and high-energy nanosecond-pulsed solid-state pro-yellow laser at 578 nm is developed by intracavity second-harmonic generation of an acousto-optically Q-switched Nd:YLF/KGW Raman laser in a type I critical phase-matching LBO crystal. The first-Stokes laser at 1156 nm driven by the 1047 nm Nd:YLF laser on the π polarization is firstly generated by accessing the Raman shift of 901 cm^-1 in the KGW crystal and then turns into the pro-yellow laser at 578 nm in the LBO crystal. Substantial power and efficiency enhancements have been enabled by improving the thermal fracture pump limit with a multi-segmented Nd:YLF crystal and compensating the negative thermal lens effect of the π polarized beam with a spherical lens. Under the injected pump power of 51 W, the maximum average output power at 578 nm reaches 4.5 W with a repetition rate of 5 kHz and the pulse duration of 6.7 ns, and the resultant optical power conversion efficiency is 8.8%. Meanwhile, the pulse energy is elevated to 3.6 mJ at 1 kHz repetition rate, corresponding to the pulse duration of 5.6 ns and the peak power of up to 660 kW.