Rydberg electromagnetically induced transparency in Radio-Frequency Field

We investigate the electromagnetically induced transparency (EIT) involved a Rydberg level which is modulated with (40-100) MHz RF field. The cesium ground state 6$S_{1/2}$, excited state 6$P_{3/2}$ and Rydberg n$D_{5/2}$ state consist of three-level atomic system, where a strong coupling laser drives the Rydberg transition, $|6P_{3/2}\rangle$ $\rightarrow$ $|nD_{5/2}\rangle$, while a weak probe laser detects the EIT signal. The RF-dressed Rydberg EIT spectra show the Stark splitting and the even-th harmonic sidebands. The $m_{j}$ =5/2 Stark line intersected with the $m_{j}$ =1/2, $m_{j}$ =3/2 sidebands, which provides an Rydberg-atom-based method for the accurate calibration of the RF electric field. We also investigate the dependence of the EIT spectra on the polarization of RF field and laser beams, the results show that $m_{j}$ =5/2 strength increase with the angle, $\theta$, defined between the polarizations of the laser beams and RF field, whereas the $m_{j}$ =1/2, 3/2 sidebands strength decrease with $\theta$. We model the experimental results using a Floquet model, the simulations are excellent agreement with the measurements. The investigation in this work provides an atom-based calibration of the polarization and amplitude of the RF-field using Rydberg-atom EIT.