Title: Photothermally-Induced Nonlinearity in a Quantum Multimode Optical System

Abstract: Similar to radiation pressure, photothermal effects connect the optical path length to an intracavity field, resulting in nonlinear behavior of the resonator due to thermal effects. Here, we theoretically investigate the nonlinear optics that emerge as a result of photothermal effects in a multimode optical system composed of two cavity modes coupled via hopping coefficient and with two mechanical modes through coupling rates. We report single to double photothermally-induced transparency (PTIT) dips, and a single sharp photothermally-induced absorption (PTIA) peak, and demonstrate that photothermal and strong coupling coefficients can suppress this phenomenon. Moreover, we observe Fano resonances in the absorption profile by monitoring probe transmission in the off-resonant configuration of the transparency phenomenon. The dynamics of group delay or advance are investigated in the range of transparency such that a sharp dip can assist in achieving slow light for a longer time. Using appropriate experimental parameters, our proposed work can pave the way for future practical applications in quantum information processing based on multimode interactions.