High-Repetition-Rate 52-mJ Mid-Infrared Laser Source Based on ZnGeP₂ MOPA System

Abstract

We developed a mid-infrared ZnGeP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> (ZGP) master oscillator power amplifier (MOPA) system with an output energy of 52 mJ, operating at a 2 kHz repetition rate. The system utilizes a 2097-nm electro-optical Q-switched two-stage holmium:yttrium-aluminum-garnet MOPA laser source with a total maximum output power of 222 W. Due to transmission and depolarization losses, the incident pump power delivered to the ZGP optical parametric oscillator and optical parametric amplifier is 65.8 W and 132.9 W, respectively. We achieved a maximum average output power of 103.9 W in the 3–5 μm range with an optical conversion efficiency of 52.3%. This corresponds to beam quality factors of 10.3 and 8.6 in the horizontal and vertical directions, respectively.