Compact, 220-ps visible laser employing single-pass, cascaded frequency conversion in monolithic periodically poled lithium niobate

We report the first demonstration to our knowledge of 220-ps visible laser generation from passively $Q$-switched-laser pumped periodically poled lithium niobate (PPLN) in a single-pass, cascaded frequency-conversion process. The monolithic PPLN consists of a 1-cm section for frequency doubling the 1064-nm Nd:YAG pump laser to a 532-nm laser and a subsequent 4-cm section for generating the visible laser in a 532-nm-pumped optical parametric generation (OPG) process. In generating the 622.3-nm OPG signal wavelength we measured a $3.0‐\mu \mathrm{J}/\mathrm{pulse}$ pump threshold at the 1064-nm wavelength, 16% overall efficiency, and 35% slope efficiency at two times threshold. At ${10}^{-6}$ pump duty cycle and 20-mW average power in the visible, photorefractive damage was not observed at the phase-matching temperature of 40.3 °C.