Analysis of the hyperfine splitting spectral structure of rubidium atomic D1 and D2 lines with pressure broadening

A physical model is established to describe the broadening mechanism of rubidium atomic D1 and D2 lines, hence to improve rubidium vapor laser efficiency. Hyperfine energy level structures of rubidium D1 and D2 transitions are analyzed and plotted. Considering the effects of the isotopic frequency shift, the pressure broadening and the hyperfine energy levels splitting, contributions of every hyperfine component to the cross sections are calculated and discussed. The relationship between cross sections and the ratio of helium pressure to ethane is achieved, and the composition of the buffer gas is optimized. The broadening effects of Rb D1 line and D2 line under different buffer gas pressure are also presented. The calculation results have a good agreement with that of experiments, which shows the validity of this model. The simulations data provides a reference for the experiment to further improve the bandwidth matching between alkali atomic D2 absorption line and the diode laser pump source.