Numerical analyses on walk-off effect in periodically poled lithium niobate

This paper presents our numerical analyses on the walk-off effect in periodically poled lithium niobate(PPLN) for optical parametric chirped pulse amplification in the front-stage of PW laser system with our simulation program. Under the 527 nm, 3 ns and 300 MW/cm2 pumping condition, using 1 053 nm, 0.6 nJ stretched pulse(from 100 fs to 800 ps) as signal, our analyses show that the high-order group velocity in the parametric process has little effect on the conversion coefficiency, but it distorts both the temporal and spectral profiles of the output signal pulse, thus degrades the pulse contrast of the amplified signal through a PPLN with a poled period of 9.7 μm.