Domain reversal of periodically poled LiNbO3 with a shorter domain inverted period

Periodically poled LiNbO3 (PPLN) was fabricated with a 7.3 μm domain-inverted period, a 1.5 μm thick photoresist grating and a 3 μm pattern open width through the electric field poling process using the liquid electrode technique. After slicing the wafers to a final dimension of 30 × 10 mm2, the specimen was poled and then annealed. Second harmonic generation (SHG) was investigated to evaluate the domain reversal properties of the PPLN. The fundamental and second harmonic waves of a 7.3 μm PPLN waveguide were 1087 ± 1 nm and 544 ± 0.5 nm, respectively. The average duty cycle of the etched PPLN was estimated to be 50.6 ± 3.3%. For PPLN in Ti:LN waveguide with a 6.8 μm domain-inverted period, the fundamental guided-mode wave and the radiated SHG wavelength were 1068 nm and 534 nm. The SHG power increased proportionally to the square of the input pumping power. 330 μW of SHG power was observed for a coupled power of 29 mW with a conversion efficiency of 1.138%. The average duty cycle of the etched PPLN was determined to be 50.2%.