2019 journal article

High-harmonic generation from an epsilon-near-zero material

NATURE PHYSICS, 15(10), 1022-+.

By: Y. Yang*, J. Lu*, A. Manjavacas*, T. Luk*, H. Liu*, K. Kelley n, J. Maria n, E. Runnerstrom n ...

co-author countries: China 🇨🇳 United States of America 🇺🇸
Source: Web Of Science
Added: October 21, 2019

High-harmonic generation (HHG) from a compact, solid-state medium is highly desirable for applications such as coherent attosecond pulse generation and extreme ultra-violet (EUV) spectroscopy, yet the typically weak conversion of pump light to HHG can largely hinder its applications. Here, we use a material operating in its epsilon-near-zero (ENZ) region, where the real part of its permittivity vanishes, to greatly boost the efficiency of the HHG process at the microscopic level. In experiments, we report high-harmonic emission up to the 9th order directly from a low-loss, solid-state ENZ medium: indium-doped cadmium oxide, with an excitation intensity at the GW cm-2 level. Furthermore, the observed HHG signal exhibits a pronounced spectral red-shift as well as linewidth broadening, resulting from the photo-induced electron heating and the consequent time-dependent resonant frequency of the ENZ film. Our results provide a novel nanophotonic platform for strong field physics, reveal new degrees of freedom for spectral and temporal control of HHG, and open up possibilities of compact solid-state attosecond light sources.