Second-harmonic generation using a fiber ring resonator with a LiNbO3 waveguide and a semiconductor optical amplifier

Optical second-harmonic generation (SHG) using a fiber ring resonator has been demonstrated. A LiNbO3 waveguide with a periodically domain inverted structure and a semiconductor optical amplifier were used as the nonlinear and gain media, respectively. The quasiphase-matched condition was satisfied simply by tuning an optical bandpass filter in the resonator. SHG was enhanced by a factor of 280.