Numerical investigations on the cascaded high harmonic and quasi-supercontinuum generations in epsilon-near-zero aluminum-doped zinc oxide nanolayers

Abstract

The cascaded high harmonic generations (HHG) and quasi-supercontinuum (quasi-SC) generations by epsilon-near-zero (ENZ) aluminum-doped zinc oxide (AZO) nanolayers are demonstrated numerically. Due to AZO’s high second- and third-order nonlinear responses, the ENZ AZO nanolayer is capable of generating high harmonic waves up to the 15th order under the excitation of a pico- or femtosecond laser source. The conversion efficiencies for the third, fifth, and seventh harmonic generations, estimated by the ratio of the spectral peak power, are in theory, comparable with the experimental results of ENZ indium tin oxide and indium-doped cadmium oxide. By broadening HHG peaks, the quasi-SC generation in nanolayers with different thickness is discussed. The results of this work might be useful in designing nanoscale multiwavelength light sources.