Effect of photoresist grating thickness and pattern open width on performance of periodically poled LiNbO3 for a quasi-phase matching device

The 0.5 mm thick bulk periodically poled LiNbO3 (PPLN) crystals have been fabricated by an electric field poling process using a liquid electrode technique to investigate the effect of photoresist grating (PR) thickness and pattern open width on the periodicity and the duty cycles of PPLNs. No periodic deterioration of +Z, −Z surfaces and cross section (+Y) of PPLN with a domain-inverted period of 16.6 μm and a 3.0 μm thick PR is found. The average duty cycle of the PPLN is determined to be 49.9 ± 3.3%. It suggests that a 3.0 μm thick and a 16.6 μm period PR with a pattern open width of 3.3 μm are advantageous to the fabricated PPLN performance.