Controllable Fast and Slow Light in the Hybrid Nanomechanical Resonator System

We propose a hybrid nanomechanical resonator (NR) system, where a NR coupled to an embedded quantum dot (QD) driven by two-tone fields is also coupled to another NR via the Coulomb interaction, and investigate the absorption spectra of the probe field under both the condition of resonance and off-resonance. The absorption spectra in resonance presents a means to determine the coupling strength of the two NRs. In the off-resonance, the absorption spectra can exhibit double Fano resonance, and the positions of the double Fano resonances are related to the interaction of the two NRs, the frequencies of the NRs, and the pump detuning. Furthermore, the double Fano resonances are accompanied by the rapid normal phase dispersion, which indicates the slow- and fast-light effect. We can obtain that the group velocity index is tunable by the interaction between the two NRs, the detuning, and the different resonator frequencies, which can reach the conversion from the fast light to slow light.