Actively Mode-Locked Fiber Optical Parametric Oscillator

We demonstrate active mode locking of a fiber optical parametric oscillator (FOPO). By inserting an amplitude modulator (AM) into a continuous-wave pumped FOPO loop, intracavity loss is varied periodically. When the modulation frequency of AM coincides with the harmonics of longitudinal modes spacing of the loop cavity, stable 10-GHz pulse train can be obtained. By adjusting the intracavity filter, the wavelength of the pulse train can be tuned over 21 nm.