Thursday, November 11, 2010
Controlling the flow of light with a novel optical transistor: "Their optical microresonator has two characteristics: first, it traps light in a tiny glass structure, guiding the beam into a circular pattern. Second, the structure vibrates, like a wine glass, at well-defined frequencies. Because the structure is so tiny (a fraction of the diameter of a human hair), these frequencies are 10,000 times higher than a wineglass vibration. When light is injected into the device, the photons exert a force called radiation pressure, which is greatly enhanced by the resonator. The increasing pressure deforms the cavity, coupling the light to the mechanical vibrations. If two light beams are used, the interaction of the two lasers with the mechanical vibrations results in a kind of optical 'switch': the strong 'control' laser can turn on or off a weaker 'probe' laser just as in a electronic transistor."