Exciton-induced frequency shift in high-harmonic generation from solids
Phys. Rev. B 113, 214315 – Published 15 June, 2026
DOI: https://doi.org/10.1103/9923-wgw8
Abstract
Spectroscopy serves as a key experimental pathway for probing many-body dynamics. Among them, high-harmonic generation (HHG) spectroscopy is particularly valued for its subcycle temporal resolution. Recent investigations have confirmed that excitonic effects in crystals can significantly enhance harmonic signal yield. The influence of excitonic effects on harmonic frequency have yet to be addressed. In this work, we theoretically demonstrate the collaboration mechanism to the frequency shift in the high-harmonic spectrum through two key excitonic effects: band gap renormalization and Rabi frequency renormalization. The observed band gap renormalization leads to an asymmetry of harmonic emission efficiency between the rising and falling edges of the driving laser pulse, with higher efficiency during the falling edge. This further results in a redshift of the harmonic spectrum. By contrast, the Rabi frequency renormalization with Pauli-blocking correction exhibits a tendency toward a blueshift via enhanced rising-edge emission, yet its synergy with band gap renormalization results in a pronounced redshift. In this work, we establish a direct link between exciton dynamics and the HHG process.
