The Resonance Bragg-scattering Spectroscopy Of Rb Atoms

The accuracy of optical frequency measurements of atomic transitions is very important in the Atoms physics. But because of transition of atom, the accuracy of frequency of the atomic transition was limited. In the early 1970s, saturated absorption was invented and it can eliminate the Doppler effect. So the atomic transition frequency can be measured precisely. Besides saturated absorption, degenerate four-wave-mixing was studied too. In 1972, Horoche and Hartmann el. proposed the population difference grating for the first time. At the same time, degenerate four-wave-mixing (DFWM) that is something with the population difference grating was studied widely by the person. But the relation of DFWM and Bragg scattering is needed to further studied. And the study will provide theoretical foundation to the physical mechanism of DFWM and it can provide a higher sensitivity spectroscopy signal for the stabilization of the laser frequency.A backward resonance Bragg-scattering (RBS) spectroscopy from a population difference grating (PDG) is presented in the dissertation. The spectroscopy has a novel high-resolution and a high signal-to-noise (S/N).This provide a good spectroscopy signal for he laser frequency stabilization. A pump beam propagate through Rb atoms in the z direction and the other pump beam propagate through Rb atoms in the-z direction. In this case, a standing-wave was created by the interference between the two pump beams in the atomic vapor which periodically modulates the space population distributions of two levels in the Rb atoms. And a population difference grating (PDG) is formed. Then, a probe beam, having the identical frequency and the orthogonal polarization with the SW pump field, is Bragg-scattered by the PDG. The scattered light is the backward resonance Bragg-scattering (RBS) spectroscopy. The main works are as following:1) The basic theory and the usual structures of the DFWM are briefly introduced.2) The Bragg-scattering spectroscopy of Rb D1 is studied. And we prove experimentally that the Bragg-scattering spectroscopy is really comesfrom population difference grating.3) The Bragg-scattering spectroscopy of Rb D2 is studied.The characterized works among the above are as follows:In our experiment, The bragg-scattering spectroscopy of Rb D2 is observed firstly, and the signal has a novel higher-resolution and a higher signal-to-noise than the saturated absorption spectroscopy. The relationship between the bragg-scattering signal and the power of the three lights is studied by changing the three lights's power. There are only two Rb atomic levels. This is different with the Bragg reflection from the EIG which have three atomic levers. Besides in the experimental process, the probe beam and the two pump beams have the same frequency. For the past three decades, the four-wave-mixing (FWM) processes in various atomic medium have been extensively studied theoretically and experimentally, and the used FWM configuration is the backward geometry generally. In this structure, the probe beam is incident on the atoms at a small angleθwith the direction of the forward pump beam. While in our backward geometry, theθis 0°. There are two Glan-laser prisms with an extinction ratio 105. The generated backward Bragg-scattering light can be separated from the direction of backward beam with a Glan-laser prism.