Utilization of silicon optical coatings for transverse-mode suppression in high-power oxide-confined vertical-cavity surface-emitting lasers

Abstract

Engineering of the electric-field standing-wave pattern of oxide-confined vertical-cavity surface-emitting lasers (VCSELs) via a scalable, high-refractive-index silicon optical coating is demonstrated to achieve high-power, single-transverse-mode emission. The electron-beam deposition of a thin silicon film atop a standard VCSEL structure reduces the amplitude of the electric-field standing wave over the quantum well gain region, raising the threshold modal gain. Patterning the coating into the shape of an annulus increases the threshold modal gain in the periphery of the VCSEL aperture overlapping with the higher-order transverse modes while leaving the central region unaffected. This patterning creates a radially dependent threshold modal gain profile, suppressing higher-order modes and encouraging operation in a single-fundamental mode. High-power continuous-wave single-mode emission with an output power of 7.43 mW in 850 nm AlGaAs-based VCSELs with silicon coatings is demonstrated, as well as submillamp threshold currents, thermal rollover delay, and a side-mode suppression ratio exceeding 30 dB for single-fundamental-mode operation at room temperature.