Self-collimated unstable resonator semiconductor laser

Self-collimation of the output is achieved in an unstable resonator semiconductor laser by providing a large concave mirror (M sub 1) and a small convex mirror (M sub 2) on opposite surfaces of a semiconductor body of a material having an effective index of refraction denoted by n, where the respective mirror radii (R sub 1, R sub 2) and beam radii (r sub 1, r sub 2) are chosen to satisfy a condition (R sub 2)/(1+r sub 1) = (n-1)/n, with a value of geometric magnification 1 less than or equal to M less than or equal to (n+1)/(n-1) where r (sub 1) and r (sub 2) are the radii of counterpropagating beams at respective mirrors of radii R (sub 1) and R (sub 2).