Two-color transparency in a hybrid photothermal cavity system

The photothermal effects can make an optical cavity transparent to a weak probe field when a strong driving field is applied (Ma et al. in Sci. Adv. 6:eaax8256, 2020). This system provides a photothermal analog of the standard (single) electromagnetically induced transparency. Here, we suggest a novel scenario by introducing into the system a qubit (two-level system), which, besides allowing to achieve the two-color (double) transparency, strongly enhances the transparency effects. When the hybrid system is illuminated by a strong coupling field, the output field is shown to experience both sub- and superluminality at different frequencies.