Diode-pumped eye-safe laser source exceeding 1% efficiency

We describe an all-solid-state, diode-pumped, eye-safe laser source at 1.61 microm, based on a Nd:YAG laser and a noncritically phase-matched KTP optical parametric oscillator. Total energy conversion efficiencies of the 1.064-microm pump to 1.61-microm signal and 3.1-microm idler approach 50%, with 35% conversion to 1.61 microm alone. This device produces 1.6 mJ at 1.61 microm with a wallplug efficiency of 1.1% and is readily scalable to higher energies. Tunability over 1.6 to 1.54 microm is obtained by rotation of the KTP crystal about its z axis, with 1.54-microm output obtained for propagation along the y axis under noncritical phase matching.