Second-harmonic generation in periodically poled GaN

We report the experimental demonstration of second-harmonic generation in periodically poled GaN by first-order quasiphase matching. The periodically poled structure was grown by plasma-assisted molecular-beam epitaxy. We observed about 9 μW of second-harmonic power from a fundamental input laser wavelength of 1658.6 nm with a normalized conversion efficiency of 12.76% W−1 cm−2. The ability to perform nonlinear wavelength conversion by periodic poling and the fact that GaN has a very wide window of transparency, pave the way for GaN to be used for nonlinear optical devices in telecommunications as well as a nonlinear light source for biochemical detection in the far infrared and deep ultraviolet.