Optical nonreciprocity in optomechanical structures.

We demonstrate that optomechanical devices can exhibit nonreciprocal behavior when the dominant light-matter interaction takes place via a linear momentum exchange between light and the mechanical structure. As an example, we propose a microscale optomechanical device that can exhibit a nonreciprocal behavior in a microphotonic platform operating at room temperature. We show that, depending on the direction of the incident light, the device switches between a high and low transparency state with more than a 20 dB extinction ratio.