Hybrid electromagnetically-optomechanically induced transparency in an atom-assisted optomechanical system

We study the reflected and transmitted output properties of a weak probe field incident upon an optomechanical cavity separated by a membrane oscillator and filled with two-level cold atoms. We find that electromagnetically induced transparency (EIT) and optomechanically induced transparency (OMIT) may simultaneously exist owing to separate cavity-atom coupling and cavity-oscillator coupling, respectively. It is more interesting that the hybrid EIT and OMIT phenomena can be manipulated on demand to exhibit various spectral features on dispersion, transmission, and reflection. In particular, we discover the new hybrid double transparency window (a narrow OMIT dip appearing inside the wide EIT window), analogous to double EIT for a four-level atomic system in inverted-Y configuration. Meanwhile, we can reduce the hybrid EIT-OMIT to a single EIT or OMIT shape by changing the magnitude of the driving field power or the atomic number as desired. Furthermore, by changing the system's detuning it is possible to change the location and the profile of the EIT, therefore switching the shape of the hybrid EIT-OMIT from symmetric to asymmetric, as well as for the profile to change from a absorption dip-like EIT to dispersion-like EIT in both real and imaginary parts of the output probe field. Also, by modifying system's detuning we have control over the distribution of the output energy, something difficult to achieve with only one of the sub-systems available.