Electrically Tunable Coupling Between Band-Edge Lasing and Whispering Gallery Modes in Liquid Crystal Microdroplets

This study explores the enhancement of band-edge laser performance through the coupling with whispering gallery modes (WGMs) in electrically tunable blue-phase liquid crystal (BPLC) microdroplets. BPLCs, known for their fast electro-optical response and photonic bandgap properties, are confined within microscale droplets to induce WGMs, which significantly improve band-edge lasing efficiency. A reversible coupling between band-edge and WGM lasing modes is demonstrated by applying an external electric field. The WGMs, formed by total internal reflection along the BPLC microdroplet boundary, reduce the lasing threshold to improve the performance of the band-edge laser. This dual-mode operation also enables to dynamically control the laser's wavelength and polarization with a wide range, expanding its applicability in optical communication and sensing technologies. These findings provide a valuable approach based on the coupling mechanisms between photonic bandgap materials and WGMs, contributing to the future development of highly tunable and adaptive photonic devices.