A vacuum ultraviolet (VUV) laser with microbeam spot and tunable repetition rate for the time-of-flight ARPES

Vacuum ultraviolet (VUV) light sources employed in time-of-flight angle-resolved photoemission spectroscopy (TOF-ARPES) typically operate at repetition rates ranging from hundreds of kHz to several MHz. Such sources featuring micron-scale beam spots demonstrate capabilities for investigating electronic structures in spatially confined regions. In this study, we developed a 177 nm laser system with a tunable repetition rate (200 kHz-2 MHz) and a measured beam spot size of ∼5 µm. This system achieves a maximum ultraviolet output power of 3 mW at a 200 kHz repetition rate, with measured beam quality factors of Mx2≈1.34 and My2≈1.23 in the vertical and horizontal dimensions, respectively. The combination of micron-scale spatial resolution and high repetition rate enables efficient electronic structure characterization in targeted material regions while benefiting from the ultrahigh data acquisition rates of TOF-ARPES. This new laser paves the way for studying the electronic structure of materials at specific regions and the rapid collection of data with TOF-ARPES.