典型的TE CO2激光脉冲, 通常由高功率窄脉冲(100 ns)和低功率长拖尾部分(3~5 μs)组成。采用一种简单的小孔等离子体开关技术可以实现对低功率长拖尾部分的有效吸收和散射, 保留需要的高功率窄脉冲前沿部分, 达到激光脉冲压缩和整形目的。详细研究了小孔位于不同离焦距离时整形激光脉冲波形的变化, 获得了整形激光脉宽、能量与离焦距离的变化关系, 实现了50~110 ns的窄脉冲CO2激光输出。进一步研究发现, 小孔等离子体开关的使用寿命主要由激光脉冲能量、重复频率、整形脉冲宽度决定。通过该技术实现的窄脉冲CO2激光可以用于极紫外光刻等离子体光源、激光雷达等领域的研究。

The typical pulse from a TE CO2 laser consists of a 100 ns sharp spike followed by a long tail region spanning about 3-5 μs. A simple pinhole plasma shutter was employed for eliminating the long tail part of the pulse due to strong laser absorption and scattering. Moreover, it remained the sharp spike of the pulse, thus the pulse width was modified. The shaped laser pulse waveforms at different pinhole positions were measured. The relationships between the laser pulse width, laser energy and defocus length were obtained, the pulse width of the CO2 laser from 110 ns to 50 ns was varied using the method. Further study indicates that the life of the pinhole plasma shutter is mainly determined by the laser pulse energy, repetition frequency, and shaped pulse width. It is shown that this plasma shutter will be used as a tool for short CO2 laser pulse shaping in the search for EUV source and lidar development.