Tunable slow light in quantum dot molecule-embedded coupled cavities with photothermal effect

The system optical response in quantum dot molecule (QDM)-embedded coupled cavities with photothermal effect is investigated theoretically. Couple resonator-induced transparency can be found first when only considering the photon tunneling between the double cavities. After implanting QDMs with tunneling effects into the right cavity, three transparency windows are observed due to QDMs and tunneling-induced transparency (TIT) therein. The fourth transparency window is formed due to photothermally induced transparency (PTIT). The results indicate the system absorption can be tuned by changing the system coupling strengths and frequency detunings. Furthermore, the transmission and group delay of the probe field are examined. Especially, the group delay in different transparency windows can be adjusted by the tunneling effect in the QDMs, and the group delay in PTIT can also be controlled by the system coupling strengths, etc. The research provides a new way of using the TIT to control the PTIT, which may be applied to design novel nanophotonic devices.