A widely tunable quasi phase matched optical parametric oscillator was demonstrated by using periodically poled LiNbO 3 (PPLN) with a multigrating structure. With a 1064 nm acousto optically Q switched Nd∶YVO 4 pump laser, a tunable IR output from 1.436 μm to 1.7 μm was obtained. The threshold was 10.3 μJ with pulses repetition rate of 10 kHz. The maximum average output power of signal is 42.5 mW with pump to signal conversion efficiency of 12.5%.