采用多通腔望远镜谐振腔结构的10MHz重复频率飞秒钛宝石激光器特性研究

Generation of femtoseond Ti:sapphire laser at 10MHz repetition rate by extending laser cavity with a telescope

通过在钛宝石激光腔内引入望远镜长腔系统增加腔长,实现了重复频率低到10MHz的飞秒激光振荡,在5W的抽运功率下获得了平均输出功率200mW、单脉冲能量20nJ的稳定输出.在此基础上分析了腔内不同色散情况下的输出脉冲光谱和脉宽特性,结果表明在腔内存在一定负色散的情况下,锁模脉宽可接近转换极限,最短脉宽可达56fs.而在正色散的情况下,锁模输出的脉宽较宽,并且随着腔内正色散的增多,脉宽可到大于600fs,锁模光谱也呈马鞍形.

We demonstrated a femtosecond Ti：sapphire oscillator at 10MHz repetition rate by introducing a specially designed multi-pass telescope to increase the cavity length. Stable mode locking laser with average power of 200 mW is obtained under 532nm laser pump of 5W power,corresponding to a single pulse energy of 20nJ. Based on this laser,we further explored the characteristics of pulse duration and spectrum with the net intracavity group-delay dispersion （GDD）. The result indicates that the near-bandwidth-limited pulse can be obtained when a little net negative GDD exists,the optimized pulse duration as short as 56fs was generated in this case. The positive GDD will lead to a widened pulse with the increase of positive GDD,and the pulse duration can extend to more than 600fs with the largest allowable positive GDD.