Abstract

Ferroelectric domain inversion in optical materials with high nonlinearity such as KTiOPO₄, LiNbO₃, LiTaO₃, allows design and fabrication of quasi-phase-matched (QPM) structures where the noncritical parametric interaction over the whole tuning band can be achieved utilising the highest nonlinear coefficient in these materials, d₃₃.PPKTP has an effective nonlinear coefficient of about 8-10 pm/V, it can be operated at room temperature, requires less stringent temperature stabilisation and is less susceptible to the photorefractive effect as compared to LiNbO₃. The QPM structures in PPKTP with thickness of up to 3 mm have been primarily used to generated mJ-level parametric pulses [1]. In this work we demonstrate that nonlinearity in PPKTP is large enough to realise OPO thresholds around 10 µJ in 10 mm to 20 mm long QPM structures when pumped at 1064 nm wavelength from a LD-pumped Nd:YAG laser.

© 2000 IEEE