Abstract

Recently a semiconductor laser with a resonator defined by a concentric-circle waveguide diffraction grating (CCG) was shown to oscillate in a circularly symmetric mode.¹ In this paper we discuss the nature of the optically pumped laser emission from such a laser. We have observed in the best case a relatively narrow-divergence beam (<1°) that is circular in cross-section. Superpositions of higher-order azimuthal modes are obtained when asymmetries in the pump or grating structure are introduced. Despite the broad-area geometry of the laser, it does not show evidence of filamentary behavior. The polarization and spectral properties of the laser emission are also examined. The CCG laser resonator shows great promise for producing a high-power, narrow-divergence, coherent beam that is two-dimensionally symmetric.

© 1992 Optical Society of America