Vertical Cavity Laser Arrays with Planar Lateral Confinement

Abstract

Surface emitting laser (SEL) arrays(1,2) are important for a variety of applications such as parallel optical signal processing. In this paper we report on the fabrication of vertical cavity strained layer (InGaAs/GaAs) SEL structures in which lateral laser definition is achieved using proton inplantation. Low threshold currents and good differential quantum efficiencies are obtained in both pulsed and cw operation at room temperature. For example, for 10 micron lasers, we measure ~4 ma threshold currents at approximately 4 volts, with 20% single facet differential efficiency in pulsed operation. Cw operation has been achieved with nearly the same operating characteristics. The proton implantation process which defines the laser structure is attractive for several reasons. It produces no exposed surfaces which lead to current loss. It allows for relatively efficient heat conduction compared to etched structures. The sample remains planar, facilitating integration with other devices and resulting in mechanically robust structures. Further, this process essentially allows for decoupling of optical and current confinement, providing greater control over spatial mode characteristics. Measurements on 10,20 and 40 micron diameter devices will be presented. A 1024-elenent electronically addressable array will briefly be described.