Controlling spontaneous chiral symmetry breaking with competing optical Kerr and cascaded second-order nonlinear processes?

The optical Kerr effect empowers the generation of optical frequency combs and quantum fields. Moreover, it can trigger the spontaneous symmetry breaking of photonic chirality due to the intrinsic imbalance between self-Kerr and cross-Kerr coefficients. The strength of optical Kerr effect is typically treated as an unalterable property determined by the photonic material and structure.

In this work, we break this stereotype by developing tunable Kerr nonlinearity without modifying photonic materials and structures. This is realized by the interference between the intrinsic Kerr and the cascaded second-order nonlinearities. We demonstrate the enhancement, suppression, and direction inversion of Kerr effects with the same device. Furthermore, we show the modification of the ratio between self- and cross-phase modulation coefficients. This leads to the control of spontaneous chiral symmetry breaking conditions in the photonic ring cavity with symmetric pumping.