Applied Physics

Directing Optical Traffic

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Science  04 Sep 2009:
Vol. 325, Issue 5945, pp. 1183
DOI: 10.1126/science.325_1183c

Optical applications such as quantum cryptography and communication are reliant on the ability to direct single photons between sender and receiver stations. Though there are several implementations capable of generating single photons, the direction of photon emission tends to be random, and the coupling efficiency into the carrier medium (an optical fiber) tends to be rather low. Toishi et al. place a quantum dot in a specially prepared photonic crystal cavity which controls the lifetime of the quantum dot and the direction of the emitted photons. Through careful design of the photonic crystal to match the output modes of the source with the mode of the carrier fiber, they show that they can increase the coupling efficiency into the fiber. The designer optical components should find direct application in opto-electronic circuitry.

Opt. Express 17, 14618 (2009).

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