Abstract

A PPLIN OPO pumped by 1.064 μn laser (Nd:YAG), is usually tunable from 1.45-4 μm.¹ To extend the tuning range, the OPO output waves can be mixed in another crystal to generate difference frequency. A scheme of the experimental setup is shown in Fig. 1. A Q-switched Nd:YAG laser serves as the pump source, which generates pulses with a duration ~7 ns. Pump beam diameter was compressed from 2.7 mm to 1 mm by a telescope. The OPO resonator was a linear cavity with flat mirrors, selected to resonate at the signal frequency as a singly resonant oscillator (SRO). The PPLN crystal, having the grating period of 31 μm with dimensions of 40 mm × 5 mm × 1 mm is placed in a temperature controlled oven. PPLN crystal placed in between dielectric coated mirrors, M1 and M2, formed the PPLN OPO. The OPO produced output, tunable from 1.71 to 2.81 μm, with the crystal temperature varying from 40°C to 175°C. The measured tuning curve and the calculated Sellmeier fit is shown in Fig. 2.

© 2002 Optical Society of America