High-harmonic generation in CdTe with ultra-low pump intensity and high photon flux

• Main Authors: Long, Zhe, Yang, Hang, Tian, Kan, He, Linzhen, Qin, Rui, Chen, Zi-Yu, Wang, Qi Jie, Liang, Houkun
• Other Authors: School of Electrical and Electronic Engineering
• Format: Article
• Language: English
• Published: 2023
• Subjects: Engineering::Electrical and electronic engineering; Gallium Compounds; Harmonic Analysis
• Online Access: https://hdl.handle.net/10356/171523
• Institution: Nanyang Technological University

An ultra-low pump intensity and high photon flux have been long pursuits of high harmonic generation (HHG) in solids. However, there is lack of a criterion to identify a pristine solid material exhibiting such characteristics. Here, we report systematic investigation into HHG from a cadmium telluride (CdTe) bulk crystal with a flat band dispersion near the Fermi level which leads to a large density of states. The measured pump intensity for the 31st harmonics (229 nm) is only 75 GW/cm2, one order of magnitude lower than that of other pristine crystals including two-dimensional materials reported so far. A comparative measurement shows CdTe has two-to-three orders of magnitude stronger HHG than silicon does, and high HHG yields in the ultraviolet region compared to GaSe. A high photon flux of ~ 6 × 1012 photons/s (5th −8th) with a robust long-time sustainability is obtained. This work offers a route towards compact vacuum ultraviolet laser sources.