Spectroscopy Between Excited States Of Caesium And Rubidium Atoms And Its Applications In Precise Measurement And Laser Frequency Stabilization

Spectroscopy is the study of the interaction between light and matter, while the spectroscopy between excited states is a doppler-free and high-resolution spectroscopy, so it can be used in basic research and practical applications. It can be used to laser frequency stabilization, to detect level structure of Rydberg atom, to nonlinear optics, to measurement of hyperfine structure splitting in excited states, to optical filtering and so on. Electromagnetically induced transparency (EIT) is a phenomenon wherein a resonant probe laser is transmitted through the medium coupled by a coherent coupling laser. The spectra of EIT in ladder-type atomic system have a narrow line width, high signal-to-noise ratio (SNR) and background flat, so it can be used to measurement of hyperfine structure splitting in excited states and laser frequency stabilization. However, it needs frequency modulation, another spectroscopy, two-photon polarization spectroscopy (TPPS), need not frequency modulation in the experimental system, it improve frequency stability of laser which interaction to excited state transitions.Base on the ladder-type atomic system, we investigated spectroscopy between excited states in caesium and rubidium atomic system, and its application on measurement of hyperfine structure splitting in excited states and laser frequency stabilization. Our main works in this thesis are as follows:1) In order to obtain electromagnetically-induced transparency (EIT) spectra with high signal-to-noise ratio, EIT has been investigated based on the cesium (Cs) 6Si/2-6Pi/2-8Si/2 ladder-type atomic system. The influence of scanning mode, the alignment of coupling and probe laser beams and the laser power on the properties of EIT spectra was discussed. On this basis, high-SNR and narrow line-width DROP spectra of transition is achieved under a proper condition.2) Based on high SNR signals, we employ an optical waveguide phase modulator and a confocal Fabry-Perot cavity. The hyperfine structure splitting of the Cs 8S1/2 is (876.32±0.50)MHz. The hyperfine magnetic dipole constant is determined to be A=(219.08±0.12)MHz. Also, the systematic effects are studied.3) The two-photon polarization spectroscopy (TPPS) of rubidium atoms has been investigated based on the 5Si/2-5P3/2-4D5/2 ladder-type atomic system. Compared with other transitions, the cycling transition shows a much better signal-to-noise ratio. The TPPS cycling transition signals versus the pumping laser’s intensity is investigatived. The frequency of a 1529nm laser diode is stabilized when frequency discrimination ability is stronger. The minimum value of Allan variance is ay(τ)= 1.3×10-11 at a interrogation time of τ=100 s. The locking technique of modulation-free TPPS clearly improve the long-term frequency stability of laser.