For a particular mode stabilization, the polarization stabilization method whose control signal is intensity is usually used. However, mode stabilization at the gain curve center is difficult in this method. Moreover, detection of the intensity is uncertain due to temperature drifts in the detector sensitivity and amplifiers, and contamination in the cavity mirror and detector surface, resulting in decreasing the frequency stability. In this experiment, intermode beat frequency change by Frequency Pulling which is strongly related to the mode position was utilized for the stabilization. The difference frequency of two intermode beats generated by the center mode and two other modes which oscillate at each side of the center mode is used as a control signal. It is convenient for the stabilization that the position of this frequency variation corresponding to the most intense center mode oscillation is at middle of its slope. Because the control signal based upon the frequency can be processed digitally, this stabilization method is free from uncertainties which is inevitable in the polarization stabilization method. |
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Cited by 2 scholarly publications.