Injection locking of intracavity SHG lasers

A single-frequency laser source is attractive because nonlinear frequency conversion in an external resonator allows generation of shorter wavelengths approaching the ultraviolet region. In order to obtain an efficient and stable single-frequency green laser source, we proposed up to 100% output from the incident fundamental power to the second harmonic output by placing a "booster" within an externally resonant doubler. We extend this approach to obtain a higher SHG power than the fundamental input power. A similar experiment was previously performed at a lower power. We assume a unidirectional ring resonator Nd:YAG laser.