GaInAsP/InP buried-heterostructure surface-emitting diode laser with monolithic integrated bifocal microlens

Abstract

A new surface-emitting diode laser has been demonstrated, which consists of a buried-heterostructure waveguide gain region on one side of the substrate and a bifocal microlens of 210 μm diameter on the other side. The bifocal microlens is composed of a collimating lens in the center (70 μm diameter) and a spherical mirror in the surrounding region, for output collimation and optical feedback, respectively. Accurate alignment between the gain region and the microlens has been obtained by using the focused light spot produced by the latter. Initial device results show room-temperature pulsed threshold currents around 92 mA (with a low of 70 mA) and far-field patterns with a narrow central lobe of 1.25°.