Single Whispering Gallery Mode in Mesh-Structured Tubular Microcavity with Tunable Axial Confinement

Single-mode lasing with high-beam quality and wide-range spectral purity is of fundamental importance in scientific and technical applications. Lacking a mode selection strategy, achieving single whispering gallery mode (WGM)-type lasing remains a challenge. Herein, a wide-range tunable single-WGM resonance in a mesh-structured tubular microcavity is realized by combining WGM resonance with distributed feedback effect, and the single mode can be systematically and precisely tuned by tailoring the geometry parameters of the hole array. In addition, switching between single mode and multimode WGM can be achieved at different axial directions of one individual tubular microcavity. The structure provides additional degrees of freedom to manipulate the resonant spectra characteristics and the spatial distribution of resonant modes, thus having a promising future in micro-/nano-optical devices.