Research On Sideband Suppressed ⁸⁷Rb Atomic Filter Method Based On Buffer Gas

In recent years,with the rapid development of quantum technology,Faraday anomalous dispersion optical filter(FADOF)has played an important role in space optical communication,laser frequency stabilization,lidar remote sensing system and other fields.However,in the case of high pump power,high temperature and strong magnetic field,FADOF will produce complex multi-peak effect and unstable transmission spectrum,which will bring some influence to the application of FADOF.In order to solve these problems,the thesis carried out related research on using buffer gas to suppress sideband multimodal effect.The main research work is as follows:(1)Using the rubidium atom vapor chamber,temperature control system,magnetic field system and other components to design and build an experimental optical path system for studying the FADOF filtering performance of ⁸⁷Rb 780nm transition.And based on the experimental system,the correlation tests of doppler broadened spectrum and the saturation absorption spectrum are carried out.At the same time,the corresponding theoretical spectral lines are deduced and calculated,and the experimental spectral lines are in good agreement with the theoretical calculations.(2)Based on the theory of atomic spectroscopy,the relationship between the deflection angle of the Faraday magneto-optical rotation effect and the magnetic field,atomic number density,atomic gas cell length and other variables is studied.By calculating the atomic absorption coefficient,circular dichroic coefficient and circular birefringence coefficient,the calculation method of the FADOF filter system transmittance is obtained.And under certain conditions of pump light power(3.25m W),the transmission spectrum of ⁸⁷Rb 780nm FADOF filter system changes with temperature and magnetic field,respectively.The experimental conditions for the best transmission spectrum(transmission is 86%,bandwidth is 2.39GHz)are temperature of 170? and magnetic field of 140Gs.The experimental spectrum under these conditions is basically consistent with the calculated results.(3)In order to eliminate the complex multi-peak phenomenon at the sideband frequency of the pure ⁸⁷Rb 780nm transition FADOF filter system in the actual FADOF application,it is proposed to use the ⁸⁷Rb atomic gas chamber filled with argon and nitrogen mixed buffer gas at a ratio of 1:1.5.Under certain conditions of pump light power(3.25m W),the changes of transmission spectrum under different temperatures,different magnetic fields and different amounts of buffer gas have been studied.A transmission spectrum with a sideband suppression ratio of 66.7%,a center transmittance of 54%and its bandwidth performance without significantly reduced is obtained.And from the perspective of the relaxation of atomic energy levels and optical pumping,the mechanism suppression of the sideband transmission peaks of the FADOF transmission spectrum line by the buffer gas is phenomenologically analyzed.