Kerr effect on optical induced transparency and group delays in a photothermal cavity

The thermal-induced nonlinear effect in a micro-cavity with small mode volume is extremely important for studying the optical cavity’s physical properties. In this work, we discuss the Kerr effect acting on the photothermally induced transparency (PTIT) and group delays in a photothermal cavity. We analyze the optical bistability with the thermal and Kerr nonlinear effects in the photothermal system, which directly impacts the dynamical stability and the threshold for bistability, eventually leading to an increase in the number of photons in the steady state. Meanwhile, the Kerr nonlinear effect greatly modifies the Fano-like PTIT in the system with photothermal effect, and the window is effectively compensated to symmetrical PTIT by Kerr-induced cavity frequency redshift. A group delay and advance are observed in the phase of the transmitted probe field, which enables light to be stored in the milliseconds range. The results demonstrate the possibility of enhancing or steering the performance of PTIT and group delay in nonlinear optical cavities, and it will find some applications in optical sensing and communications.