Photothermally induced transparency in coupled-cavity system

We aim to study the properties of the output probe field (OPF) in a system composed of two coupled-optical cavities. Two fields such as strong pump and a weak probe field drives the left cavity whereas the right-side cavity is coupled to mechanical oscillation via photothermal effect. The two cavities are coupled with optical coupling strength $J$. Single photothermally induced transparency (PTIT) in a single cavity is realized via thermal effect (Sci. Adv. 6, eaax8256 (2020)). Following the idea, we report double PTIT in coupled-cavities system. The control of single to double PTIT is realized in the proposed system by properly adjusting the coupling strength $J$. We further show the enhancement of slow light by adjusting the coupling strength ($J$) between the cavities. Our proposed scheme facilitates experiments to investigate photothermal effects in an array of optomechanical systems.