ZnGeP2 parametric amplifier

A ZnGeP2 parametric amplifier was constructed, and the small-signal gain of a 3.39-mu m He-Ne laser in excess of 10 was measured. With a 2.06-mu m Ho:Tm:Er:YLF laser having a nominal 50-ns pulse length as a pump, small-signal gain was measured as a function of pump power. When compared with the predicted gain, taking into account the beam profile of both the pump and the signal, good agreement was found at low pump powers. However, the observed gain was less than predicted at higher pump powers. Pump-induced loss at 3.39 mu m, a phenomenon not observed in other nonlinear crystals such as AgGeSe2, causes the difference. Pump-induced loss was observed when the ZnGeP2 crystal was tilted away from the phase-matching angle. Pump-induced loss at 3.39 mu m was characterized and found to be directly proportional to the pump energy. (C) 1998 Optical Society of America.