Optomechanically induced ultraslow and ultrafast light

Slow and fast light is an important fascinating phenomenon in quantum optics. Here, we theoretically study how to achieve the ultraslow ultrafast a passive-active optomechanical system, based on ideal optomechanically induced transparency (OMIT). Under conditions of OMIT, abnormal (inverted) window will emerge accompanied with very steep dispersion, resulting that can be easily achieved at by adjusting dissipation rates two cavities, even usual mechanical linewidth (such as Hz linewidth). Particularly, decay rate passive cavity tends gain active cavity, stopped achieved. Similarly, tuning coupling strength system.