为提高半导体激光器的频率稳定性,利用原子法拉第反常色散光学滤波器(FADOF)超窄带的选频透射特性,将其置于半导体激光器的外腔中作选频元件,采用光反馈的方法,使得透射率低的激光频率分量被抑制,透射率高的激光频率分量被加强,有效地实现了光反馈激光稳频。利用Cs原子法拉第反常色散光学滤波器工作于D2线852 nm的4峰窄带透射状态,通过调节半导体激光器的温度和电流,调谐半导体激光器的输出波长,将激光器锁定在任何一个透射峰上,用26%的光反馈量,使稳频后的激光频率长期稳定性保持在75 MHz/2 h以内,而且采用这种稳频方法的输出激光中心波长一直稳定在频率基准上,没有单方向漂移。同时,还实现了Cs原子法拉第反常色散光学滤波器稳频半导体激光器结构的一体化,使其具有实用性。

An atomic Faraday anomalous dispersion optical filter (FADOF), which characterized with its ultra narrow peaks of wavelength transmissions, is employed to improve the frequency stability of a semiconductor laser. The FADOF is put into the external cavity of the semiconductor laser as a frequency selector to restrain the lasing wavelength to the transmission wavelength of the FADOF, and in this way, the laser frequency locked to the atomic transmission is realized effectively through the optical feedback. The FADOF used for laser frequency stabilization here is worked at Cs D2 line of 852 nm with four narrow transmission peaks. The output wavelength of the laser can be locked to any one of the four transmission peaks of the Cs FADOF, by changing the temperature and inject current of the diode laser. The long time stability of the wavelength remains drafting about 75 MHz/2 hours using 26% feedback. The central wavelength of diode laser is locked on any one of the transmission peak of FADOF which is stable in nature, so there is no long time wavelength drafting. In addition, the whole structure of the frequency-stabilized semiconductor laser is designed to be a compact unit, and is suitable for practical application.