Abstract: Frequency doubling pulse laser around 532nm has been obtained through irradiating PPLN crystal with a single mode laser beam, which emitting from a Yb-doped mode-locked fiber laser. Based on Quasi Phase Matching technology, the SHG (Second Harmonic Generation) wavelength tuning can be realized by changing incident angel of fundamental wave that irradiating the PPLN. Pumped by a mode-locked fiber laser which has a bandwidth of 60 nm, the pulse laser SHG (Second Harmonic Generation) is obtained from the PPLN, and the output laser has a bandwidth of 1.5 nm and center wavelength of 532 nm. The SHG wavelength was continuously detuned by adjusting the angle of PPLN crystal. It worked out an angle tuning range of 0° to 25°, corresponding to the SHG wavelength tuning from 531.8nm to 535.6nm. The wavelength detuning is in good agreement with the theory.

Key words: nonlinear optics; wavelength tuning; quasi phase matching (QPM); periodically poled lithium niobate (PPLN); mode-locked fiber laser