Growth of ZnGeP2 single crystals by modified vertical Bridgman method for nonlinear optical devices

The effects of temperature gradients and crucible materials on ZnGeP2 single crystal, grown by vertical Bridgman method, were studied. Growth were carried out in quartz crucible, quartz crucible with carbon film coated on the inner wall, and PBN crucible respectively. X-ray diffraction (XRD), X-ray fluorescence (XRF) and Fourier transform infrared spectrophotometry (FTIR) were employed to characterize the quality of grown crystals. By annealing in ZnGeP2 powder, its optical properties were found to be improved. A ZnGeP2 optical parametric oscillator (ZGP-OPO) sample was fabricated from the annealed crystal. Laser experiments were carried out on ZGP-OPO by 2.1 µm, 7 kHz laser to obtain tuning laser in the range of 3-5 µm.