Controllable transmission spectrum via electromagnetically induced transparency with Rydberg atoms

Controllable transmission spectrum is highly desirable in optics. Here we investigate the transmission spectrum and its control using cascaded electromagnetically induced transparency (EIT) with Rydberg atoms. We show that the transmission spectrum of the probe field can exhibit one or no EIT transparency window if the atomic vapor contains mainly the Rydberg-blockaded three-level atoms or Rydberg four-level atoms. Moreover, the transmission spectrum can be actively controlled by tuning the ratio between the control and driving laser fields, rendering various applications in optical processing, such as optical absorbers.