Symmetry analyses of high-order harmonic generation in monolayer hexagonal boron nitride

Abstract

The high-order harmonic generation (HHG) of the monolayer hexagonal boron nitride driven by near-infrared laser pulses with different polarization is investigated with the real-time time-dependent density functional theory. The harmonic yield can be manipulated by tuning the laser intensity, ellipticity, waveform, and polarization. The symmetry of the interacting system is used to analyze various characteristics of the harmonic spectra. We theoretically verify the generation of circular high-order harmonics from solid by a single circularly polarized and a counter-rotating bichromatic circularly polarized field, which is consistent with the predictions of the selection rules. The selection rules based on dynamical symmetry analyses are derived in detail. We find that for the same energy the incident laser pulse, the bichromatic co-rotating and counter-rotating circularly polarized laser fields can produce harmonics more efficiently than a linearly polarized laser. Extension of HHG in 2D materials to the XUV regime and the possible realization of circularly polarized harmonics pave a way to the development of novel nanoscale attosecond light sources.