Patent ID: 7310183

Claim:
A diffractive outcoupler for use in a cavity of a laser, the diffractive outcoupler comprising: a transparent substrate having a first side and a second side; a surface phase grating including rectangular grooves having a groove depth D formed on the first side, the surface phase grating dividing incident radiation into a transmitted portion, a first diffracted portion, and a second diffracted portion; a first reflector situated with respect to the transparent substrate for receiving the first diffracted portion from the surface phase grating and reflecting the first diffracted portion back toward the surface phase grating; and a second reflector situated with respect to the transparent substrate for receiving the second diffracted portion from the surface phase grating and for reflecting the second diffracted portion back toward the surface phase grating, wherein the groove depth D substantially satisfies the relation D=λ(k+1/2)/(n FH −1), where k is a nonnegative integer, λ is a fundamental wavelength of the incident radiation, and n FH is refractive index of the transparent substrate at the fundamental wavelength λ.