Tunable reflection based on electromagnetically induced transparency

Detailed analysis on the tunable reflection based on electromagnetically induced transparency is presented. We adopt the configuration of a four-level atom driven by a bichromatic standing wave. The Maxwell–Liouville equations for the steady state are employed to describe the mechanics of the system and numerically solved using the parameters of Rb87 in a magneto-optical trap. The analytic solutions are also obtained, which lead to the conditions for getting the higher reflectivity. Theoretically, under such conditions, the reflectivity could be arranged as high as 90% with the coherence decay rate already considered. The controllability of the reflectivity provided by adjusting the intensities and detunings of the coupling fields (the two components of the bichromatic standing wave) is investigated as well. The result shows that the two coupling fields can impact the reflectivity differently. Such a feature allows us to control the reflectivity more flexibly.