Experimental Demonstration of Spontaneous Chirality in a Nonlinear Microresonator.

Physical review letters

PubMedID: 28157372

Cao QT, Wang H, Dong CH, Jing H, Liu RS, Chen X, Ge L, Gong Q, Xiao YF. Experimental Demonstration of Spontaneous Chirality in a Nonlinear Microresonator. Phys Rev Lett. 2017;118(3):033901.
Chirality is an asymmetric property widely found in nature. Here, we propose and demonstrate experimentally the spontaneous emergence of chirality in an on-chip ultrahigh-Q whispering-gallery microresonator, without broken parity or time-reversal symmetry. This counterintuitive effect arises due to the inherent Kerr-nonlinearity-modulated coupling between clockwise and counterclockwise propagating waves. Above an input threshold of a few hundred microwatts, the initial chiral symmetry is broken spontaneously, and the counterpropagating output ratio exceeds 20:1 with bidirectional inputs. The spontaneous chirality in an on-chip microresonator holds great potential in studies of fundamental physics and applied photonic devices.