TE CO₂ laser narrow pulse modification based on a pinhole plasma shutter

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 s. 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.