Switching of whispering gallery mode in hexagonal GaN microdisk by change in condition of reflection surface

Optical microresonant mode switching in a hexagonal GaN microdisk, which acts as a whispering gallery mode (WGM) and quasi-WGM (QWGM), has been demonstrated by a change in the condition of the reflection surface under a room temperature photoluminescence (RT-PL) measurement. It has been confirmed that only the WGM in the microdisk, which uses all side walls of a microdisk as the reflection surface, was strongly affected by attaching another microdisk on a side wall. The result indicates that the WGM can be controlled independently by external factors.