Large angle acceptance of quasi-phase-matched second harmonic generation in a homocentrically poled LiNbO3

A periodically poled LiNbO3 (PPLN) with homocentric semicircle domain structure is prepared, by which a high efficiency second harmonic generation with large angle acceptance is demonstrated. The angle acceptance and conversion efficiency of this PPLN is compared to the PPLN with a strip pattern. In our case the poling period is 26 μm, and the crystal is 9 mm long. The corresponding angle acceptance is 30°, while that of strip pattern PPLN is 2.36°. The conversion efficiency of PPLN with homocentric semicircle pattern and strip pattern is 36.7% and 33% respectively.