Reconfigurable Self-Phase Modulation Enabled by Cascaded Nonlinear Backaction in Integrated Photonics

Self-phase modulation is ubiquitous in optical systems: It provides foundational functionality to numerous photonic technologies, such as soliton generation and ultrafast pulse compression. However, it remains challenging to directly modify the coefficient of self-phase modulation, which is typically regarded as a fixed property of optical materials and structures. In this work, we overcome this limitation and demonstrate reconfigurable self-phase modulation with an integrated photonic cavity. This is achieved by introducing the engineered backaction from the reservoir photonic resonance through the cascaded second-order nonlinear coupling. The coefficient of self-phase modulation is tuned from -2.7 to +4.7 of its intrinsic value. With negative coefficients, we observe the anomalous self-phase modulation, where photonic resonances are shifted towards higher frequencies. With the reconfigurable self-phase modulation, we further demonstrate the control of spontaneous chiral symmetry breaking in the integrated photonic ring cavity.