Patent ID: 7254153

Claim:
A laser, comprising: first and second composite layer-structures, each thereof including a multilayer semiconductor gain-structure surmounting a mirror-structure; first and second mirrors, said first and second mirrors and said mirror-structures being arranged as resonator mirrors of a first unidirectional ring-resonator with said gain-structures of said composite layer-structures located in said first ring-resonator; an arrangement for energizing said gain-structures to cause fundamental laser-radiation to circulate in said first ring-resonator; a first optically nonlinear crystal located in said first ring-resonator and arranged to convert said fundamental laser-radiation to second-harmonic radiation; and a second ring-resonator arranged to circulate said second-harmonic radiation therein, said first and second ring-resonators being arranged to be partially coaxial with resonator axes thereof following a common path through said first optically nonlinear crystal.