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All Optical Transistor

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This false-color scanning electron micrograph of the microresonator used in the EPFL study shows a silica toroid in red supported by a gray silicon pillar on a semiconductor chip.

Credit: T. Kippenberg / EPFL

Researchers at Ecole Polytechnique Federale de Lausanne's Laboratory of Photonics and Quantum Measurements have built a device that acts like an optical transistor. The device makes use of an optical microresonator, which traps light in a tiny glass structure that guides the beam into a circular pattern, and the structure vibrates at well-defined frequencies. When light is injected into the device, the photons exert a force greatly enhanced by the resonator that deforms the cavity and couples the light to the mechanical vibrations. If two light beams are used, the interactions of the two lasers with the mechanical vibrations result in an optical switch in which the strong control laser can turn on or off a weaker probe laser. "We have known for more than two years that this effect was theoretically possible," says Max-Planck Institute scientist Albert Schliesser.

Called optomechanically induced transparency, it could enable an optical light field to be converted into a mechanical vibration for the first time, and could have a wide range of applications in telecommunications. Moreover, the switchable coupling could allow researchers to control optomechanical systems at the quantum level.

From Ecole Polytechnique Federale de Lausanne
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