Coupled-mode induced transparency in aerostatically-tuned microbubble whispering gallery resonators

TL;DR

This paper demonstrates coupled-mode induced transparency in microbubble whispering gallery resonators using aerostatic pressure tuning, supported by simulations and experiments, with potential applications in sensing.

Contribution

It introduces a novel method of achieving transparency in microbubble resonators through aerostatic tuning and detailed modeling of pressure effects.

Findings

Pressure-induced frequency shifts differ for radial modes.

Finite element simulation matches experimental results.

Transparency spectrum observed during mode crossing.

Abstract

Coupled-mode induced transparency is realized in a single microbubble whispering gallery mode resonator. Using aerostatic tuning, we find that the pressure induced shifting rates are different for different radial order modes. A finite element simulation considering both the strain and stress effects shows a GHz/bar difference and this is confirmed by experiments. A transparency spectrum is obtained when a first order mode shifts across a higher order mode through precise pressure tuning. The resulting lineshapes are fitted with the theory. This work lays a foundation for future applications in microbubble sensing.