Abstract

Quasi-phasematching was proposed as a means of phasevelocity matching a nonlinear optical process by Armstrong et al¹ before the advent of birefringent phase-matching. In 1989 Lim et al² first demonstrated a quasiphasematched second harmonic interaction in lithium niobate using titanium diffusion to induce periodic domain reversal. Following the lead of Yamada et al,³ L. E. Myers et al⁴ demonstrated electric field poling of 1/2 mm thick congruent lithium niobate at room temperature with high quality domains over a 2 mm long interaction region. The interaction region was extended to 5 mm and which enable the first QPM OPO to be demonstrated. That OPO was pumped by a Q-switched Nd:YAG laser and tuned in the 1.6 to 3.0 µm IR region. The measured threshold was less than 1 mJ of input energy due to the use of noncritical phasematching and the d₃₃ nonlinear coefficient.

© 1995 IEEE