【作者】 李沼云；

【导师】 吴正茂；

【作者基本信息】 西南大学 ， 光学， 2009， 硕士

【摘要】 近年来,光纤通信迅猛发展,点到点传输系统迅速提高,密集波分复用(DWDM)系统向着超大容量超长距离发展,这对激光器等核心器件提出了更高的要求。普通半导体激光器由于对温度的变化非常敏感从而其激射波长具有不稳定性,难于实现对激射波长的精准控制,从而限制了通信系统的进一步的发展。利用光纤光栅外腔对现有普通半导体激光器进行选模是实现激光器压窄线宽,改善输出光谱最方便、经济和有效的手段之一。因而有必要对其进行深入细致的研究,以期获得更高精确度和更稳定激射波长的相干光源以满足信息高速、大容量传输的需要。本文对外腔半导体激光器(ECSL)和光纤光栅工作原理及选模机制进行了较为系统的分析,采用耦合模理论,利用传输矩阵(TMM),将光纤光栅外腔半导体激光器(FGECSL)的有源区,无源区和光栅视为一个完整的系统,考虑半导体激光器、外腔及光纤光栅(FG)三者的共同耦合作用,在确定光纤光栅外腔半导体激光器的激光纵模分布后,对FGESCL的激射波长随FG外腔长度的变化情况展开了理论研究。在此基础上,结合多模速率方程组,对光纤光栅外腔半导体激光器的P-I特性及边模抑制比(SMSR)等输出特性进行了理论分析。结果表明:随着光栅长度的增加,FGECSL的激射波长向长波长方向呈现一定漂移和出现周期性波动,而FGECSL对应的阈值增益则总体显现下降趋势,其细节呈现一定的波动;同时,FGECSL的阈值载流子数密度和阈值电流随之降低,在阈值电流附近P-I曲线出现了扭曲现象。更多还原

【Abstract】 In recent years,with the rapid development of the optical communication and the improvement of the point-to-point transmission system,the large-capacity and long haul-dense wavelength division multiplexed(WDM) transmission technologies have been rapidly developed,which put forward new requirement for the semiconductor lasers.However,the conventional semiconductor lasers have some disadvantages such as mode hoping,temperature instability and poor linearity,which limited the further development of the communication system.A fiber Bragg grating as an external feedback component in the external cavity semiconductor laser(ECSL) has been considered as one of the most effective methods for realizing the narrow line-width, the easily controllable working wavelength and the temperature stability,etc.Therefore, the characteristics of ECSL should be studied farther to acquire the coherent light source with more accurate and stable lasing wavelength.In this paper,the characteristics and operation principles of the ECSL and the fiber Bragg grating have been introduced.Then based on the coupled mode theory,the transfer matrix model of the fiber grating external cavity semiconductor laser(FGECSL) has been established.According to this mode,the active region,passive region and. grating of the FGECSL has been treated as an integral system,after taking into account the joint contribution of semiconductor laser,external cavity and fiber grating to the phase condition,the mode distribution of the FGESCL can be determined.As a result, the effect of the FG external cavity length on the lasing wavelength of the FGESCL is investigated theoretically.Finally the output spectrum of the FGECSL has been investigated depended on the steady-state multimode rate equations.The results can provide instructive insight in to the characteristics of FGECSL.更多还原