两种调制方式下主从激光器同步性能的理论研究

 以单周期信号为例，数值模拟并讨论了注入频率和注入光场波动强度对主从式半导体激光器同步性能的影响。分别通过直接调制和外部调制两种方式获得单周期信号，并采用改进的参数——相似指数评价系统的同步性能。研究结果表明：当注入强度足够大时，系统实现注入锁定同步，外部调制的相似指数大于内部调制；注入强度恒定时，同步品质几乎不受调制指数的影响，而受调制频率的影响；由于内部、外部调制引起主激光器的输出反相，两种调制方式下同步品质随调制频率的变化趋势也相反。

Theoretical analysis on synchronization performances of master-slave laser subjected to two modulation methods

Taking single period injection as an example,the influence of frequency and fluctuation amplitude of the injection field on the dynamics and synchronization of semiconductor lasers are studied numerically.The single period injection is obtained through direct modulation and external modulation,and a modified correlation coefficient called similarity index is used to evaluate the synchronization performance.The results show that injection locking synchronization is realized when injection rate is large enough.In the injection locking regime,similarity index is larger for external modulation than that for direct modulation.If injection rate keeps unchanged,synchronization is little affected by modulation index,but it is affected by modulation frequency.Since outputs of the master laser are antiphase for direct modulation and external modulation,the fluctuations of similarity index with modulation frequency for the two lasers are contrary.