Wide Bandgap Semiconductor-Based Surface-Emitting Lasers: Recent Progress in GaN-Based Vertical Cavity Surface-Emitting Lasers and GaN-/ZnO-Based Polariton Lasers

With edge-emitting GaN-based lasers in commercial systems, attention is shifting to more demanding and rewarding emitters. These encompass microcavity (MC)-based vertical cavity surface-emitting lasers (VCSELs) and polariton lasers. The impetus centers on applications such as high-speed/high-resolution laser printing/scanning technology, lighting, and new types of coherent but nearly thresholdless optical sources. Room-temperature operations of GaN-based VCSELs by electrical injection have been recently reported, and the research on GaN-based VCSELs is segueing into new opportunities such as polariton-based lasers. While still in its infancy, polariton lasing in GaN-based MCs at room temperature has been observed. Observation of spontaneous emission buildup in polariton lasing emission is attributed to a Bose-Einstein condensate of cavity polaritons. However, the realization of a polariton laser by electrical injection is still being pursued. In this paper, we discuss the recent progress in wide-bandgap semiconductor-based VCSELs and GaN-/ZnO-based polariton lasers.