Self-injection-locking of a CW-OPO by intracavity frequency-doubling the idler wave

We report on the observation of self-injection-locking of the signal wave o f an optical parametric oscillator (OPO) with the intracavity frequency dou bled idler wave. The two-mirror OPO is based on a periodically poled LiNbO3 (PPLN) crystal and pumped with a grating stabilized, continuous-wave (CW) single-frequency diode master-oscillator power-amplifier (MOPA) system. Sim ultaneous quasi-phase-matching (QPM) of OPO and second harmonic generation (SHG) is provided in the same crystal which carries two different domain gr atings. The beat of the signal wave and the frequency-doubled idler wave is suppressed within a 500-kHz wide frequency range centered around zero as e xpected for self-injection-locking. The measurements prove the feasibility of optically phase-stabilized by-three-division of an optical frequency wit h CW-OPOs using cascaded nonlinearities. (C) 1999 Optical Society of Americ a.