Optically induced transparency in a micro-cavity

Electromagnetically induced transparency has the unique ability to optically control transparency windows with low light in atomic systems. However, its practical applications in quantum physics and information science are limited due to rigid experimental requirements. Here we demonstrate a new mechanism of optically induced transparency in a micro-cavity by introducing a four-wave mixing gain to nonlinearly couple two separated resonances of the micro-cavity in an ambient environment. A signature Fano-like resonance was observed owing to the nonlinear interference of the two coupled resonances. Moreover, we show that the unidirectional gain of the four-wave mixing can lead to the remarkable effect of non-reciprocal transmission at the transparency windows. Optically induced transparency may offer a unique platform for a compact, integrated solution to all-optical and quantum information. Scientists have used light to make a micro-cavity transparent to light, which may lead to compact components for all-optical processing. Since its discovery in 1991, the phenomenon of electromagnetically induced transparency in atomic systems has generated much excitement due to its potential for all-optical and quantum information processing. But it is hard to incorporate in chips because it generally uses atoms in the gaseous phase. Now, Wenjie Wan at Shanghai Jiao Tong University in China and co-workers in China and the United States have realized the equivalent effect—optically induced transparency (OIT) —in a micro-cavity by using a nonlinear optical effect known as four-wave mixing. The researchers anticipate that OIT may offer a new avenue for compact all-optical and quantum information processing.