Control and manipulation of electromagnetically induced transparency in a nonlinear optomechanical system with two movable mirrors

We consider an optomechanical cavity made by two moving mirrors which contain a Kerr-down-conversion nonlinear crystal. We show that the coherent oscillations of the two mechanical oscillators can lead to splitting in the electromagnetically induced transparency (EIT) resonance and the appearance of an absorption peak within the transparency window. In this configuration, the coherent-induced splitting of EIT is similar to driving a hyperfine transition in an atomic Lambda-type three-level system by a radio-frequency or microwave field. Also, we show that the presence of nonlinearity provides an additional flexibility for adjusting the width of the transparency windows. The combination of an additional mechanical mode and the nonlinear crystal suggests new possibilities for adjusting the resonance frequency, the width and the spectral positions of the EIT windows, as well as the enhancement of the absorption peak within the transparency window.