Optimization of diffusion bonding process for QPM GaAs crystals

It’s an effective method to produce mid infrared laser that CO2 laser frequency doubling by using quasi-phase-matched (QPM) crystal. The main problem in the preparing diffusion bonding crystal is controlling the defects. In this paper, the bonding temperature, pressure, time and other parameters are optimized to reduce the interface loss. When the bonding temperature is 700°C , the bonding pressure of 0.27kg/mm2, a 49 layer QPM GaAs crystal was fabricated, and the interface loss of the single layer was less than 0.13%. Using the prepared QPM-GaAs crystal for second harmonic generation, 23% SHG efficiency was achieved in a CO2 laser with 10.56μm wavelength, 219 mJ pulse energy and 110 ns pulse width.