Whispering gallery mode splitting on filling-based microresonators for refractive index sensing

Abstract

This paper reports the whispering gallery mode (WGM) splitting behavior as-observed between pairs of size-matched microspheres with tight-binding positions. Dye-doped microspheres were excited by pulsed lasers in order that the WGM laser spectra could be monitored. Via analysis of experimental results, we investigated the effects of spacing between two coupled microspheres on coupling strength, and found that coupling strength was increased with decreasing spacing between the microspheres through mode splitting spectra. We demonstrated the effects of environment refractive index (RI) of coupling spot on mode splitting spectra through dripping liquid on the slit of the bi-spheres, and observed that coupling strength changes with the influence of RI. Furthermore, temperature-dependent experiments showed that temperature change will not disturb the mode splitting behavior, this structure exhibits potential for self-referencing sensing.