High-power operations of single-mode surface grating long oxide aperture VCSELs

Abstract

A high-power single-mode vertical cavity surface emitting laser (VCSEL) based on a slow light mode (SLM) concept is demonstrated. Shallow surface gratings were implemented to select a single slow light mode in mm long oxide aperture VCSELs. The vertical structure and well-established fabrication processes are unchanged from those of conventional 850 nm VCSELs. An electron-beam lithography is used to form a 1st-order shallow grating on the surface. Thanks to the low effective index and the intensity penetration of the SLM to the surface, the grating fabrication process is much easier than conventional guided mode distributed feedback lasers. A stable single mode with a high side suppression ration of more than 30 dB is obtained for the entire current range under CW operations. A narrow divergence of 0.038° in far field patterns is achieved for a 6 mm long device. A record single-mode power of more than 5 W is realized before saturation under 50 ns pulse operations. Unlike long cavity in-plane edge emitting lasers, a SLM-based VCSEL can provide higher output powers without limitation of catastrophic optical mirror damage. The high power, superior mode stability, and good beam quality of our unique design paves a way for VCSELs to be used for wide ranges of high-power applications.