Patent ID: 8194708

Claim:
A laser apparatus comprising: a folded cavity defined by a first end mirror, a second end mirror and an output coupler; an optically isotropic active gain medium in the cavity between the first end mirror and the output coupler that generates fundamental optical radiation at a fundamental wavelength; and a non-linear crystal in the cavity between the second end mirror and the output coupler that converts the optical radiation at the fundamental wavelength to an output wavelength using type 1 phase matching; wherein the first end mirror has high reflectance at the fundamental wavelength, the second end mirror has high reflectance at the fundamental wavelength and high reflectance at the output wavelength, and the output coupler has high reflectance at one polarization of the fundamental radiation, low reflectance at an orthogonal polarization of the fundamental radiation, and high transmission at the output wavelength, and wherein the output coupler acts as an intra-cavity polarizer thereby eliminating the requirement for a separate polarizing optical component.