Experimental realization of optomechanically induced non-reciprocity
  Non-reciprocal devices, such as circulators and isolators, are indispensable components in classical and quantum information processing in an integrated photonic circuit. Aside from those applications, the non-reciprocal phase shift is of fundamental interest for exploring exotic topological photonics, such as the realization of chiral edge states and topological protection. However, incorporating low optical-loss magnetic materials into a photonic chip is technically challenging. In this study, we experimentally demonstrate non-magnetic non-reciprocity using optomechanical interactions in a whispering-gallery microresonator, as proposed by Hafezi and Rabl. Optomechanically induced non-reciprocal transparency and amplification are observed, and a non-reciprocal phase shift of up to 40 degrees is demonstrated in this study. The results of this study represent an important step towards integrated all-optical controllable isolators and circulators, as well as non-reciprocal phase shifters. 
Z.Shen, Y.-L. Zhang, Y. Chen, C.-L. Zou, Y.-F. Xiao, X.-B. Zou, F.-W.   Sun, G.-C. Guo, C.-H. Dong
physics.optics