Widely tunable room-temperature green-pumped continuous-wave optical parametric oscillator from the red to mid-infrared

Abstract

We report, to the best of our knowledge, the first realization of a room-temperature green-pumped continuous-wave (cw) optical parametric oscillator (OPO), providing wide and rapid tunability directly from the red to mid-infrared. The OPO, based on fanout MgO:sPPLT crystal and pumped at 532 nm, can provide a total signal and idler wavelength tuning range over 2554 nm, from 638 to 3192 nm. By deploying finite output coupling of the resonant wave at room temperature, also for the first time, to the best of our knowledge, we achieve enhanced output power and extraction efficiency, with the OPO delivering 4.6 W of total output power with pump depletion of 75% and total external efficiency as high as 50%. We believe 638 nm is the shortest signal wavelength generated from a cw green-pumped OPO in any fanout-grating nonlinear material to date. The passive power and frequency stability, linewidth, spatial beam profile, and beam pointing stability of the output-coupled signal, which are crucial for many applications, have been studied.