Development of highly stable reference cavity to control laser oscillation frequency

[出版社版]We propose a novel and versatile technique to accurately control laser oscillation frequency. We also developed a highly stable reference cavity, which is essential for this purpose. We built a confocal Fabry-Perot cavity with a frequency resolution of 14.3 MHz as a reference cavity, whose mirrors have a reflectivity of 97 % for wavelengths of 400 and 780 nm. The resonant frequency of this reference cavity was stabilized by the 780 nm- laser light, whose oscillation frequency was locked to the cross-over resonance of the 85Rb atoms obtained by saturation spectroscopy. The resonant frequency of the free-running cavity drifted 23.4 MHz in 50 seconds. However, the stability of the resonant frequency was improved as a result to 3.3 MHz over a period of 15 minutes by controlling the cavity length to keep the 780 nm- laser light resonant in the cavity. This stability was enough to generate the reference signal to maintain the frequency of another laser for high resolution spectroscopy. Our method is applicable to the preparation of a light source to perform experiments on quantum information processing, future frequency standards, and so on