GaN microdisks with a single porous optical confinement layer for whispering gallery mode lasing

This paper details the fabrication of GaN-based microdisks with a single porous n-GaN layer positioned beneath the multiple quantum wells region on a modified green light-emitting diode epiwafer. Simulations of the longitudinal light field distribution reveal effective confinement of the light field within the multiple quantum wells region due to the presence of the single porous layer. The porous layer also demonstrates sufficient conductivity as determined through calculations and serves as an effective method for thermal dispersion. Under optical pumping, all microdisks exhibit clear whispering gallery mode (WGM) lasing at room temperature, with the lowest threshold of 13.50 μJ/cm2 achieved in a 2-μm-diameter microdisk. These findings suggest that integrating the single porous layer into GaN microdisks is a highly promising approach for achieving high-efficiency WGM micro-laser diodes with effective electrical injection and heat dispersion.