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

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10?MHz的飞秒激光振荡，在5?W的抽运功率下获得了平均输出功率200?mW、单脉冲能量20?nJ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56?fs. 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600?fs，锁模光谱也呈马鞍形. 关键词： 钛宝石激光器 飞秒脉冲 低重复频率 望远镜腔

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

We demonstrated a femtosecond Ti:sapphire oscillator at 10?MHz 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 532?nm laser pump of 5?W power, corresponding to a single pulse energy of 20?nJ. 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 56?fs 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 600?fs with the largest allowable positive GDD.
Keywords： Ti:sapphire laser femtosecond pulse low repetition rate telescope cavity