Eye-safe output from noncritically phase-matched parametric oscillators

An eye-safe source at 1.61 μm with 2.1% wall-plug efficiency is demonstrated by use of a Nd:YAG-pumped KTP optical parametric oscillator with total peak-power conversion efficiency of 70% and an energy conversion efficiency of 47%. Similar efficiencies are obtained when one employs a Nd:YLF laser as the pump source, but the signal wavelengths move into the defined eye-safe band at 1.54 and 1.55 μm. We also demonstrate 1.54-μm operation, for noncritical phase matching, with the 1.064-μm pump by propagating along the y axis of the KTP crystal.