Single-frequency 355 nm source for direct detection wind lidar

We have developed a laser based on an oscillator/amplifier design that uses diode-pumped, conductively cooled Nd:YAG slabs as the gain media. The oscillator is a telescopic ring resonator design that can be easily configured for a range of operational scenarios. An unstable version of the oscillator achieved 125 mJ/pulse with >10% electrical to optical efficiency and an M 2 of 2.5. Operated in a stable TEM 00 mode, the ring laser demonstrated >30 mJ/pulse at 100 Hz with an M 2 of 1.3. We used the 30 mJ TEM 00 output to extract the amplifiers and achieved 300 mJ/pulse of single frequency output at 50 Hz with an M 2 of 1.5. We also investigated operation of an injection-seeded version of the ring resonator operated in the marginally stable regime without the use of graded reflectivity mirrors. With this approach we demonstrated single-frequency, 50 mJ/pulse operation at 50Hz with an M 2 of 1.4 and a square, supergaussian profile. Initial third harmonic generation measurements have achieved over 40% conversion to 355 nm.