Evaluation of the wavefronts and spatial structures of ultrashort pulses passing through a micro-channel plate

Abstract: The first aim of this project is to make high-order harmonic (HHG) setups more compact and user-friendly, by including a micro-channel plate (MCP). Simulations of the transmission properties of an MCP has been performed. These simulations displayed introduced structure in the far field, but a very well behaved beam in the near field. Further, the wavefront of the zeroth order diffraction spot of MCP filtered extreme ultraviolet light from HHG, was measured, indicating that a negligible amount of distortion was introduced. The second aim is to obtain understanding of the HHG process, utilizing a chirp scan technique. A measurement was performed, validating that chirp scans are equivalent to, the desired, intensity scans, for measuring quantum path interference (QPI) in HHG. Measured QPI plots show interference structures, which could only be simulated by adding a third interference source in an existing code. This could be the first measurement of a third quantum path in HHG. Finally, a chirp scan was performed with an MCP inserted in the setup. The resulting spectra and QPI plots show substantial off-axis artifacts, although retaining much of the on-axis behavior. The findings of this project add to the knowledge of HHG and show that, even for very phase sensitive experiments, an MCP can be introduced to an HHG setup without compromising the obtained data.