Single-scan Polarization-resolved Degenerate Four-wave Mixing And Saturated Absorption Spectroscopy Based On Vector Optical Fields

The characteristics of the interaction between light and matter are closely dependent on the polarization state of incident beams.As such a dependence is closely related to the properties of the sample（structure,composition,dynamics,etc）,the polarization-resolved spectroscopy/imaging techniques provide people significant tools to retrieve the information of matters.In order to obtain polarization-resolved spectra,it’s necessary to obtain the signal intensities under different polarization states of incident beams.The existing polarization-resolved spectroscopy technology is always realized by changing the polarization state of the incident beams one by one.The spectra acquisition is slow,and the measured is required to be repeated on same sample,so it is not suitable for the study of ultrafast processes and samples with poor optical stability.In view of this,we propose a single-scan polarization-resolved spectroscopy technique using the vector optical beams with spatial-variant polarization distribution in this thesis,which includes the following specific work:1.A new method to achieve the single-scan polarization-resolved DFWM（degenerate four-wave mixing）spectroscopy is realized in Rb atomic medium using vector optical field,in which two pump beams are kept linearly polarized and a vector beam is employed as the probe beam.As the polarization and intensity of the DFWM signal is closely dependent on the polarization state of the probe beam,a vector probe beam with space-variant states of polarization is able to generate DFWM signal with space-variant states of polarization and intensity across the DFWM image.Accordingly,the polarization-resolved spectroscopy can be retrieved from a single DFWM image.To the best of our knowledge,this is the first time that the single-scan polarization-resolved spectroscopy detection has been realized experimentally with a vector beam.2.A new single-scan polarization-resolved saturated absorption spectroscopy（SAS）method is realized by utilizing a hybridly polarized beam as the probe beam in ⁸⁵Rb atomic vapor.Taking advantage of the spatial-variant polarization of hybridly polarized probe beam,we are able to retrieve the polarization-resolved information of SAS from the single signal frame.Then,the polarization dependence of SAS from two transitions,i.e.,|5S_1/2,F=3>→|5P_3/2,F′=4>and|5S_1/2,F=3>→|5P_3/2,F′=3>are investigated and compared.It is found that for the“closed two-level transition”as|5S_1/2,F=3>→|5P_3/2,F′=4>,strong polarization dependence is observed.By contrast,no polarization dependence is observed for“open two-level transition”as|5S_1/2,F=3>→|5P_3/2,F′=3>.The experimental results are well explained with assistance of the transition paths among the Zeeman sub-hyperfine energy levels under different polarization configurations.In this paper,the single-scan polarization-resolved DFWM and SAS technique based on vector optical fields are proposed and implemented,which provide a powerful tool for detecting samples with poor optical stability and ultrafast optical process.