外腔长度变化对外腔半导体激光器边模抑制比的影响

Influence of External Cavity Length on FBG-ECL's Side Mode Suppression Ratio

根据光纤光栅外腔半导体激光器（FBG—ECL）的等效腔模型，通过分析半导体激光器（LD）、外腔及光纤光栅（FG）三者的共同作用，利用光纤光栅外腔半导体激光器的相位条件确定FGESL的激光纵模分布，理论上研究了FGESL的边模抑制比（SMSR）随FG外腔长度的变化．结果表明：SMSR的大小跟外腔长度的选择有很大的关系，在其他参数相同的情况下，外腔长度的微小变化可以引起边模抑制比很大的波动．从总体上看，外腔较长时的比外腔较短时的边模抑制比要小；当外腔长度为8～11mm时，光纤光栅半导体激光器有比较高的边模抑制比（SMSR〉40．8dB），并且边模抑制比随外腔长度的变化比较平稳.

According to equivalent external cavity approximation model, after analyzing the co -function of the joint contribution of semiconductor laser, external cavity and Fiber Grating fion, the mode distribution of the FGESL＇ s can be determined. As a result, （FG） to the phase condithe effect of the FG external cavity length on the Side Mode Suppression Ratio （SMSR） of the FGESL is investigated theoretically. The numerical results show：Under the condition of short external cavity, the SMSR is in deep relation to the external cavity length, but the SMSR of longer external cavity is smaller than the SMSR of shorter external cavity on the whole. And for 8 - 11 mm of the external cavity length, the SMSR of the FGESL was better（ SMSR 〉 40.8 dB）, and the SMSR become more flattened.