调制转移光谱稳频的研究

532nm激光的碘吸收谱线的频率被国际计量委员会(CIPM)推荐用于频率计量标准．激光频率标准对长度和时间的计量是很重要的。碘分子在532nm附近有丰富的强吸收谱线．可以作为频率稳定的绝对参考谱线。使用532nm单块固体激光器，在375kHz新的调制频率下．利用调制转移技术，将激光频率调谐到^127I2的R(56)32—0跃迁的吸收谱线，并观察到该吸收谱线相应的15条超精细结构分量。通过展宽的调制谱线可以看出375kHz的调制频率得到比312kHz调制频率更高的鉴频敏感度．并在实验上成功地将激光频率稳定在碘的超精细吸收谱线的α10，分量上长达10h，估计稳定度在10^-13量级。准确的频率稳定性正在两台激光器上用拍频的方法进行测量。

Research on Frequency Stabilization of Modulation Transfer Spectroscopy

Iodine-stabilization lasers are becoming important wavelength standards and optical frequency standards. The frequency value of Iodine R (56) 32-0 transition was recommended as the standard frequency for practical realization of the meter by CIPM in 2001. Molecular iodine has rich strong absorption lines near 532 nm that can provide the absolute references for frequency stabilization. A monolith solid laser was tuned at the spectrum of transition R (56) 32-0 of iodine molecule with new modulation frequency 375 kHz. And 15 hyperfine components of this spectrum were observed using modulation transfer spectroscopy. The sensitivity of frequency detecting with 375 kHz modulation frequency was higher than that with 312 kHz modulation frequency by broadening one hyperfine component. The laser frequency was successfully locked at a 10 component for no less than 10 hours. The frequency stability was estimated about level of 10 -13, and the exact value of frequency stability is under measurement by frequency beating between two same kind of lasers.