Nanosecond pulsed narrow-linewidth all-fiber source for ZGP-OPO pumping

We demonstrate a pulsed three-stage master oscillator power amplifier (MOPA) at a wavelength of 2047 nm and its application for mid-IR generation via pumping a ZnGeP$_2$ (ZGP) optical parametric oscillator (OPO). A maximum MOPA output power of 19.8 W is reached while achieving a diffraction limited beam quality M$^2$ <1.1. By applying the MOPA setup to pump a ZGP crystal in a linear OPO cavity, a combined signal and idler mid-IR output power of 8.1 W is reached. For the highest mid-IR output power, a mid-IR conversion efficiency of 44 % and beam quality factors M$^2$ of 2.2 and 2.0 are determined for signal and idler, respectively.