State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics,Chinese Academy of Sciences, Wuhan 430071，China
Abstract：Zeeman split takes place for the hyperfine level structure of neutral atoms where magnetic field exists. In addition, being excited by right circularly polarized light and left circularly polarized light, atoms obey different transition rules. So, the absorption peak between the hyperfine Zeeman level shifts with respect to the absorption peak without magnetic field. Accordingly, the authors demonstrated a kind of simple and flexible method to stabilize the frequency of diode laser. The linewidth of diode laser was reduced to less than 1 MHz using this method. Through analyzing the experiment results, the authors found that when the sum of both shifts of the hyperfine level of atoms excited by right circularly polarized light and left circularly polarized light was equal to the FWHM(Full Width at Half Maｘimum) of the saturated absorption peak, the laser frequency was stabilized best.
Key words：Hyperfine level structure;Dispersion line shape;Linewidth of laser;Zeeman energy level split
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