基于快速半导体可饱和吸收镜的高功率锁模皮秒掺钛蓝宝石激光器

High power mode-locked picosecond Ti:sapphire laser based on fast SESAM

利用X型四境腔中第二稳区振荡光斑大小随臂长变化关系,设计了一种快速半导体可饱和吸收镜启动的高功率皮秒模掺钛蓝宝石激光器。通过改变臂长改变SESAM表面光斑大小,进而改变SESAM表面功率密度实现锁模,采用恒温循环通水紫铜作为SESAM热沉,有效消除了高功率运转下热噪声导致的锁模不稳定。在10W泵浦功率下,利用腔内自相位调制和群速度色散相互制约机制,获得了稳定类孤子锁模脉冲,输出典型的脉冲宽度为20ps,中心波长为813nm,对应的重复频率为100MHz。在输出镜透过率为10%和20%时,输出最大功率分别为1.80W和1.95W。结果表明:这种设计对应SESAM表面较大光斑,在同样的锁模功率密度下,支持更高的腔内功率密度,适合高功率高光束质量锁模运转,最终获得近2W的稳定锁模皮秒脉冲输出。

a high power mode-locked picosecond Ti ： Sapphire laser based on fast SESAM was set up, in which the relations between the mirror spot and the arm length in second stable region was utilized. By changing the length of the arm to change the size of the SESAM surface, and then changing the power density of the SESAM surface to start the mode locking. A constant temperature water cooled copper as the SESAM heat sink, which effectively eliminated the instability of mode locking caused by the thermal noise. Under 10W pump power, a stable soliton mode-locked pulse is obtained by using mutual balance mechanism of self phase modulation and group velocity dispersion. The laser delivers 20 ps typical pulse width at a central wavelength of 813nm, and the repetition rate is 100MHz. With 10% and 20% output couplers, maximum mode-locked average power was 1.8W and 1.95W, respectively. The results show that the design had a lager spot in SESAM surface which support higher power under the same mode-locking power density. So it is suitable for high power and high beam quality mode locking operation, and finally a nearly 2W of out- put power was obtained.