Broadband mid-infrared (IR) supercontinuum laser is generated in standard single-mode fiber-28 directly pumped by a 2054 nm nanosecond Q-switched Tm,Ho:YVO4 laser. The average output powers of 0.53 W in the ~1.95–2.5 μm spectral band and 0.65 W in the ~1.97–2.45 μm spectral band are achieved at pulse rate frequencies of 7 and 10 kHz, and the corresponding optic-to-optic conversion efficiencies are 34.6% and 42.4% by considering the coupling efficiency. The output spectra have extremely high flatness in the range 2060–2400 and 2060–2360 nm with negligible intensity variation (<2%), respectively. The output pulse shape is not split, and pulse width is reduced from 29 to ~15.4 ns. The beam quality factor M2 is 1.06, measured using traveling knife-edge method, and the laser beam spot is also monitored by an IR vidicon camera.

为了探讨飞秒激光在兔眼角膜上行深板层切削的可行性,获得深板层切削的较适参数,并了解在水肿角膜上行深板层切削的准确性,将兔眼置于由同心圆扫描程序控制的三维平台上,将不同能量的飞秒激光(800 nm /50 fs)精确定位于角膜深板层,伴随平台移动激光便在角膜深板层切削。利用光学显微镜和扫描电镜(SEM)观察激光作用后角膜的形态学变化,并同徒手器械分离的板层角膜对比。当平台移动速度为200 μm/s,激光能量为4.4 μJ时切削表面比较平滑;当速度为300 μm/s,能量为6.4 μJ时切削表面较为平滑。激光组切削层面的光滑程度优于徒手器械分离组;当平台移动速度为200 μm/s,能量为6.4 μJ时飞秒激光同样可以完成在水肿角膜的400 μm深度的聚焦切削,且切削表面较为光滑。