In order to store photons, two options are available to physicists. They can try to slow them down through various physical phenomena, or trapping them in resonators that force them to spin many times before leaving them out, with losses.
Researchers of laboratory FOTON, IRCP and C2N The researchers of the laboratory have decided to combine these two solutions. For this, they used micro-resonators with whispering-gallery-modes *: 100 μm diameter spheres made of a glass of erbium-doped fluoride. When approaching an optical fiber of the micro-resonator, a part of the light that passes nearby will penetrate it. The photons will then have to perform a little less than a thousand turns in the sphere before they can leave. They will also interact with the erbium ions present, which slows them down. While the photons were doing 1000 rounds in 300 ps, they now need 2.5 ms.
The light used is in the field of telecom waves, a branch in which many detectors and sources are already available to develop applications. These studies also showed that the optical micro-resonators could reach a storage capacity of the order of their macroscopic versions. This opens for example the way to miniaturized storage systems, such as optical or quantum memories.
* In the gallery under the dome of St. Paul’s Cathedral in London, whispers can be heard at any time in the gallery due to the efficiency with which the sound waves move along its curved wall. Similarly, in an optical resonator with whispering gallery modes, the light waves propagate efficiently along the periphery of the sphere.
 Yannick DUMEIGE yannick.dumeige univ-rennes1.fr +33 2 96 46 94 31 |
Millisecond Photon Lifetime in a Slow-Light Microcavity, V. Huet, A. Rasoloniaina, P. Guillemé, P. Rochard, P. Féron, M. Mortier, A. Levenson, K. Bencheikh, A. Yacomotti, and Y. Dumeige. Phys. Rev. Lett. 116, 133902, 29 march 2016, DOI: 10.1103/PhysRevLett.116.133902
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