Experimental and numerical studies of thermal lensing and gain guiding effects in a high-power ZGP OPO

Tunable high-power coherent sources covering the mid-IR region find numerous applications in remote sensing, free space communication or defense countermeasures [1] . Besides high power, such applications require a broad tuning range and good beam quality. Optical parametric oscillators (OPO) and amplifiers (OPA) with nonlinear optical (NLO) crystals are the main approach for sources covering 3-5 μm region [2] . Zinc germanium phosphide (ZGP) has favorable properties among nonlinear materials suitable for conversion to the mid-IR region with pumping near 2 μm, where a wide choice of pump lasers with good beam quality is available [3] .