Photon’s Lifetime Extended

In the whispering gallery beneath the dome of St Paul’s Cathedral in London, whispers can be heard at any point in the gallery because of the efficiency with which sound waves travel along its curved wall. Similarly, in a whispering-gallery-mode resonator, light waves propagate efficiently along the device’s periphery. This and other properties make these structures outperform conventional optical resonators in several applications, such as microlasers. Now Yannick Dumeige from the University of Rennes 1, France, and colleagues at the French National Center for Scientific Research (CNRS), show that introducing a slow-light medium into a whispering-gallery-mode microresonator extends a photon’s lifetime in the resonator by several orders of magnitude. This feature of a resonator defines the length of time a photon can circulate in the device, and thus be stored, before being absorbed or scattered.