基于饱和吸收镜的被动锁模光纤激光器

在普通单模光纤环中插入半导体可饱和吸收镜(SESAM)作为非线性器件,实现了自启动的被动锁模光纤激光器,并产生了亚皮秒量级的稳定锁模激光脉冲。输出锁模脉冲的基频为几兆赫兹。利用基于倍频晶体的二次谐波自相关仪测得锁模脉冲的脉宽为422 fs,最窄时可达377 fs,利用光谱仪测得脉冲谱宽为6.35 nm,脉宽谱宽乘积为0.329,接近于双曲正割脉冲的变换极限。实验中激光器输出脉冲稳定,没有观察到子脉冲和直流分量。在一般的实验室条件下,未采取任何附加措施,激光器可连续稳定工作10 h以上,没有出现失锁现象。该装置结构简单,紧凑,易于调整,工作稳定,可以很方便地实现自启动锁模。

Passively Mode-Locked Fiber Laser with a Semiconductor Saturable Absorber Mirror

Using a semiconductor saturable absorber mirror(SESAM),a passively mode-locked fiber ring laser was demonstrated and stable sub-picosecond pulses were produced.The repetition frequency of pulse trains was several MHz.Nearly transform-limited 422 fs pulses with spectrum width of 6.35 nm were obtained,without any satellite pulses or pedestal.The duration of the pulses was measured by an autocorrelator with second harmonic generation,and pulses as narrow as 377 fs were achieved.During 10 hours,the laser can work stablely.The experimental setup was simple,compact,and self-started.