Solid-state high harmonic generation spectroscopy (sHHG) has emerged as a pivotal technique for delving into electronic structure, symmetry, and dynamics in condensed matter systems. In our latest manuscript, we introduce an advanced cryogenic sHHG spectrometer, uniquely designed with a vacuum chamber and a closed-cycle helium cryostat. With the aid of an in situ temperature probe, we’ve ascertained that the sample interaction region maintains cryogenic temperatures even during the application of high-intensity femtosecond laser pulses, which are responsible for generating high harmonics. Our approach paves the way for temperature-dependent sHHG measurements down to a few Kelvin. Such advancements in sHHG spectroscopy present a novel tool for investigating phases of matter that manifest at low temperatures, an area of particular intrigue for highly correlated materials.

Published article in the Review of Scientific Instruments:
https://pubs.aip.org/aip/rsi/article/95/2/023906/3267761/A-solid-state-high-harmonic-generation

Pre-print is available here: https://arxiv.org/abs/2309.01049