High-power nanosecond optical parametric oscillator based on a long LiB3O5 crystal

We report on a compact high average power optical parametric oscillator (OPO) pumped by an all-solid-state nanosecond 532 nm laser. Based on the merit of non-critically phase-matched crystal without walk-off effect, a 50-mm-long LiB3O5 (LBO) crystal is used as OPO nonlinear crystal to enhance the conversion efficiency and increase the output power. With the available mirror set, continuous tuning from 778 to 1036 nm for signal wave is obtained by changing LBO phase-matching temperature. The maximum average power of signal output is up to 9.4 W at 900 nm for pump power of 18 W inside the LBO crystal, corresponding to a conversion efficiency of 52% only for the signal output. This is, to the best of our knowledge, the highest signal average power generated by nanosecond OPO in single bulk LBO.