Through the cascade excitation of 852-nm continuous-wave(CW)laser and 509-nm nanosecond pulsed laser,the electromagnetically-induced transparency(EIT)spectroscopic signals of ladder-type three-level cesium atoms with Rydberg state are obtained by using a room-temperature cesium vapor cell.The power of 509-nm pulsed laser beam is～176 W,while the pulse repetition frequency ranges from 300 kHz to 100 MHz and can be continuously adjusted.The laser pulse duration runs from 1 to 100 ns and can be continuously adjusted.The relationship between Rydberg EIT spectroscopic signals and 509-nm nanosecond pulsed laser parameters is investigated experimentally.By changing the pulse repetition frequency and the pulse duration of the 509-nm nanosecond pulsed laser,the comb-like Rydberg atomic spectrum is obtained by using a room-temperature cesium vapor cell.Within a certain range of repetition frequency and pulse duration,the envelope of spectral lines shows a regular pattern,and the spacing between the transmission peaks is consistent with the pulse repetition frequency.By changing the 509-nm laser pulse repetition frequency and pulse duration,atoms with the specific velocity group can be excited to Rydberg state.Reducing the repetition frequency of the 509-nm pulsed coupling laser can further increase the number of atoms in the Rydberg state in comparison with the case of finite velocity group pumping of cesium atoms by a continuous-wave laser.When the repetition frequency of the 509-nm pulsed laser approaches the EIT linewidth,the number of cesium Rydberg atoms can be increased by up to 10 times.In the parameter optimization process,the dynamic characteristics of pulsed excitation in multi-level atoms,as well as the interaction characteristics between arbitrarily shaped laser pulses and multi-level atomic systems,should be considered.Pulsed laser pumping can achieve the interaction between the laser field and atomic group with a specific velocity,and its developed atomic frequency comb spectra can be used for electric and magnetic field measurements.The multi-peak structure of the spectrum can be used to more accurately determine the intensity,frequency,and phase of the micro wave electric field by measuring spectral variations.This high-sensitivity and high-resolution measurement capability is crucial for precisely measuring microwave electric fields.The pulsed coupling laser can excite atoms in a specific velocity group to the Rydberg state.High-density Rydberg atoms can improve the signal-to-noise ratio of the measured spectrum,which has potential applications in quantum sensing and quantum measurement based on Rydberg atoms.
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