Whispering-gallery-mode microbubble resonators: fabrication and characterization

Abstract

Whispering is not an effective means of communication when a considerable distance separates the two conversationalists. In spite of this, a soft whisper can travel a very long way in the right environment - a whispering gallery. In 1910, the scientist Sir John William Strutt (Lord Rayleigh) witnessed this acoustic phenomenon in the Dome of St. Paul’s Cathedral in London (see Fig. 1). Here, two people on opposite sides of the dome, up to 40 metres apart, can talk to each other by simply whispering against the curved wall. Inevitably, Lord Rayleigh - a true mathematician at heart - solved what he described as “The problem of the Whispering Gallery”. He realised that, as the whisper travels along the curved surface, it loses very little energy and so can be heard after a great distance. Conversely, when the speaker talks at normal volume, the message possesses enough energy to complete ...