New technique promises tunable laser devices

Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a phenomenon similar to an effect observed in circular galleries, such as in some cathedrals or museums, where sound waves travel across the gallery and are reflected and refocused tightly enough that a whisper on one side can be heard on the other.