Abstract

Semiconductor lasers are currently limited in output power by either catastrophic facet damage or heat dissipation. Linear arrays of lasers have been developed that produce higher power from many individual lasers.¹ Monolithic surface emitting geometries allow laser arrays to be constructed in two dimensions.^2-4 For these arrays to have high brightness, however, mutual coherence must be established between the individual lasers. In addition, the individual beams must be combined to produce a single-lobed far-field pattern with negligible sidelobes. A new technique is presented which uses an array of high-efficiency diffractive microlenses to expand the individual laser beams and employs diffractive coupling in an external cavity to provide the necessary mutual coherence. The technique is applicable to both 1-and 2-D laser arrays.

© 1988 Optical Society of America