Ultrahigh-Q microcavity photonics: from fundamental physics to novel applications

 

Optical microcavities have become intriguing platforms for nano/micro photonics owing to their strong confinement of light field within small volumes, which enhances significantly the light-matter interactions. Ultrahigh-Q microcavities have found broad applications in coherent light sources, on chip information processing, ultrasensitive sensors and integrated quantum optics. In the recent years, Dr. Yun-Feng Xiao and his research team focus on the fundamental physics and novel applications of ultrahigh-Q microcavities. They developed the innovative fabrication techniques for on-chip symmetric/asymmetric microcavities, which laid the foundation of high performance on-chip photonic devices. As a pioneer in the field of asymmetric microcavities, Yun-Feng’s research team proposed the concept of chaos-assisted momentum transformation, through which broadband coupling to ultrahigh-Q whispering gallery modes was demonstrated, overcoming the strict condition of optical phase matching that seriously limits the device efficiency in regular microcavities. They initiated and experimentally demonstrated several groundbreaking sensing methods with ultrahigh sensitivities enhanced to single-nanoparticle level, such as microcavity mode broadening, mode splitting and dissipative interaction mechanisms. In particular, their sensors allow accurate measurement of the size distribution of atmospheric particulates, providing a new technique for air quality assessment. Now the team is developing the micro-comb technology of ultralow power consumption and ultrahigh precision, aiming at providing novel light sources in the fields of atomic clocks, optical spectroscopy, astrophysical observation, bio-imaging and LIDAR.