Tuning time and energy resolution in time-resolved photoemission spectroscopy with nonlinear crystals

TL;DR

This paper explores how nonlinear crystal properties influence the time and energy resolution in time-resolved photoemission spectroscopy, demonstrating tunable resolutions through crystal thickness adjustments.

Contribution

It provides a theoretical framework linking laser bandwidth and crystal thickness to experimental resolution limits, and experimentally demonstrates tunable resolutions using nonlinear crystals.

Findings

Achieved time resolutions of 58 to 103 fs.

Achieved energy resolutions of 55 to 27 meV.

Provided a method for flexible resolution tuning.

Abstract

Time- and angle-resolved photoemission spectroscopy is a powerful probe of electronic band structures out of equilibrium. Tuning time and energy resolution to suit a particular scientific question has become an increasingly important experimental consideration. Many instruments use cascaded frequency doubling in nonlinear crystals to generate the required ultraviolet probe pulses. We demonstrate how calculations clarify the relationship between laser bandwidth and nonlinear crystal thickness contributing to experimental resolutions and place intrinsic limits on the achievable time-bandwidth product. Experimentally, we tune time and energy resolution by varying the thickness of nonlinear $\beta$-BaB$_2$O$_4$ crystals for frequency up-conversion, providing for a flexible experiment design. We achieve time resolutions of 58 to 103 fs and corresponding energy resolutions of 55 to 27 meV.