Sensing and lasing applications of whispering gallery mode microresonators

The approaches used to confine light in small volume are indispensable in modern optics. After the discovery of Whispering Gallery Mode (WGM) in St Paul’s Cathedral in London by Lord Rayleigh in 1910, Garrett et al. found optical wave can generate WGM in optical resonator as well in 1961. Optical WGM resonator has attracted great attention due to its remarkable properties such as extremely high Q factor, small mode volume, tight confinement of modes and strong evanescent field. Recently, many novel research results based on WGM microresonators have been reported, for example, bio/chemical sensors for nanoscale objects, ultrasensitive RI sensors, tunable microlasers and narrow line width microlasers. 

Schematic diagram of Whispering Gallery Mode 

    The research group of Prof. Perry Ping Shum from Nanyang Technological University reviewed sensing and lasing applications of Whispering Gallery Mode (WGM) microresonators. Due to extremely high Q factor, small mode volume, and strong evanescent field, WGM microresonators have been widely applied into the field of sensors and microlasers. In this mini-review, the key parameters and coupling conditions of WGM microresonators are firstly introduced, including Q factor, optical coupling approaches, phase matching and critical coupling. After that, the geometries of WGM optical microcavities are presented based on their fabrication methods. Then the discussion on the state-of-the-art applications of WGM microresonators in sensors and microlasers is followed, such as, bio/chemical sensors, RI sensors, temperature sensors, humidity sensors tunable microlasers and narrow line width microlasers. Finally, the future research trend in this field is predicted.

About Team
The research fields of Professor Perry Ping Shum’s group include optical communication, optical fiber design and applications, and optical fiber sensing network technology. Recently, the group got research funds from Singapore Ministry of Education, National Research Foundation Singapore and Singapore A*STAT. Professor Perry Ping Shum is SPIE Fellow and OSA Fellow. He served as the committee member and international advisor of many international conferences. Prof. Shum has published more than 900 international journal and conference papers, and the total citation is more than 7700.

Zheng Y, Wu Z F, Shum P P, Xu Z L, Keiser G et al. Sensing and lasing applications of whispering gallery mode microresonators. Opto-Electronic Advances 1, 180015 (2018)
DOI: 10.29026/oea.2018.180015