基于甲烷分子吸收线的声光偏频无调制激光频率锁定

利用声光调制器(AOM)的偏频特性,以甲烷(CH4)分子吸收线R9支一条强吸收线(λ=1.637 8μm)作为参考频率,实现了对外腔式半导体激光器的无调制频率锁定.实验中在100 s内典型的频率起伏小于5.6 MHz,较激光器自由运转时的频率起伏34 MHz有了显著的改善.该方法实现了对半导体激光器的无调制锁频,并且适用于分子光谱领域,满足光纤通信中对激光器输出波长的要求,在波分复用领域中将有很好的应用前景.

Modulation-Free Laser Frequency Locking by AOM Based on Molecular Absorption Line of CH4

Locking the output frequency of a laser onto an available molecular absorption line can efficiently suppress the fluctuation of frequency and improve the frequency stability of the laser. By using an acousto-optic modulator(AOM)to shift the laser frequency and making the molecular absorption line of CH_4 around 1. 63 μm to be the frequency reference,an external cavity diode laser was locked within fiber wavelength range. In experiment,by locking the laser,the frequency jitter of less than 5. 6 MHz was achieved,which was greatly improved comparing with the frequency fluctuation of about 34 MHz in the condition of free running. This technique does not need to modulate the laser and can be applied to the technology of wavelength division multiplexing for ifs applicability in molecule spectrum.