注入连续光实现锁模光纤激光器的波长稳定

Wavelength Stabilization of Mode-Locked Fiber Laser via Continuous-Wave Injection

提出了一种实现锁模光纤激光器波长稳定的方法,即向锁模激光器腔内注入连续光,使某一组纵模在注入连续光的基础上起振。这组纵模在对增益介质的竞争中可以稳定地占据优势,从而实现激光器输出光谱的稳定。理论分析发现注入连续光会使锁模激光器纵模线宽变大,而线宽的增大将会增加进入纵模的连续光功率。在实验中对基于掺铒光纤放大器(EDFA)的主动锁模光纤激光器进行波长稳定,激光器的调制频率为10.06 GHz,观察到了良好的稳定效果。为进一步检验波长稳定的效果,对锁模光纤激光器进行波长稳定后,将其输出的光信号经过一个法布里-珀罗(F-P)滤波器,稳定地滤出了功率较高的纵模。法布里-珀罗滤波器的自由光谱区(FSR)为40.24 GHz,透射峰3 dB带宽为40 MHz。实验结果证明纵模被稳定在法布里-珀罗滤波器的透射峰范围内,纵模波长的波动小于40 MHz。

A novel method to stabilize the wavelength of mode-locked fiber laser was presented. A set of longitudinal modes were stimulated by the injected continuous wave （CW）, so that these modes were able to win the competition to stabilize the wavelength. Theoretical analysis showed that the linewidth of the mode-locked laser＇s longitudinal modes was broadened by the injected CW signal. Consequently the power of the CW signal entering the longitudinal modes was increased. The wavelength of an actively mode-locked fiber laser based on erbium doped fiber amplifier （EDFA） was stabilized in the experiment. The modulation frequency of the mode-locked fiber laser was 10.06 GHz. Stable longitudinal modes were observed. In order to stabilize further, the stabilized output signal was further filtered by an Fabry-Perot （F-P） filter. The free spectral rangel （FSR） of the F-P filter was 40. 24 GHz and the 3 dB bandwidth of the transmission peaks was 40 MHz. The result showed that the wavelength fluctuation of the longitudinal modes was confined within the transmission peaks. That means the maximum fluctuation was less than 40 MHz.