Excitation area dependence of lasing modes in thin hexagonal GaN microdisks

Abstract

Thin, hexagonal GaN microdisks act as optical microcavities based on the whispering gallery mode (WGM) and the quasi-WGM that can cause lasing action. We investigated the relationship between the excitation area in regular and asymmetric thin, hexagonal GaN microdisks as well as the characteristics of these lasing modes using a room temperature photoluminescence mapping technique under high-excitation conditions. The lasing modes that are preferentially exhibited in a thin asymmetric hexagonal GaN microdisk were found to depend on the most strongly excited area in the microdisk. This behavior is potentially useful for optical micro switches and similar applications.