Development of a Long-Wave Infrared Laser Source Based on Optical Parametric Amplification in ZnGeP2
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- Institutt for fysikk 
This thesis presents the design and implementation of an 8 μm laser source based on nonlinear conversion in ZGP. ZGP is an attractive material for this purpose due to its high nonlinear coefficient, good transmission at the relevant wavelengths, and high thermal conductivity.The configuration was a master oscillator/power amplifier (MOPA) system, including an optical parametric oscillator (OPO) with a 3-mirror ring resonator that allows two passes of the beams through the same nonlinear crystal. The power amplifier consisted of two optical parametric amplifiers (OPAs). The MOPA system was pumped at 2.05 μm by a Q-switched Ho:YLF laser. Each stage of the MOPA system was investigated with computational simulations to optimize the system for providing pulses at 8 μm wavelength with high energy and good beam quality. The experimental results were in good agreement with the simulations.When pumping with 360 mJ, the maximum energy achieved at 8 μm was 45 mJ with M2 = 3.1.The system was tested with different combinations of crystal lengths, and with both signal and idler as seeds, and only signal as seed in the power amplifier system. A conference paper describing the OPO has been accepted for presentation at Mid-Infrared Coherent Sources (MICS).