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.

Strain effects on high-harmonic generation in monolayer hexagonal boron nitride

“…We find that the strained HHG mechanism is closely related to the symmetry of the monolayer hBN. For the strain-free hBN, it has the reflection symmetry with respect to the B-N bond, and the three-fold rotation symmetry with respective to the center of the hexagonal lattice [53]. However, when applied stretching strains, some symmetries are destroyed, resulting in a concert change in the HHG spectra.…”

“…In addition, contributions of orientation-dependent HHG yield from the parallel and the perpendicular configuration are opposite to each other. A more detailed analysis of the selection rule for the strain-free monolayer hBN can be found in our previous paper [53].…”

Effect of Interlayer Coupling and Symmetry on High-Order Harmonic Generation from Monolayer and Bilayer Hexagonal Boron Nitride

“…Because of its high damage threshold, hBN is a promising candidate for light emission in the far UV region via HHG [36,37]. Theoretical investigations on the various characteristics of HHG from hBN, such as rotation anisotropy, time-frequency behavior and wavelength scaling of harmonic yields, have been pursued recently [16,38,39]. Improvements in growth technology have enabled hBN to be stacked in various ways [40][41][42].…”

High Harmonic Generation Driven by Counter-Rotating Bicircular Laser Fields from Polar Chemical Bonds in h-BN

“…CHHs can be generated not only in gaseous medium [2,4,6] but also from crystalline solids [9][10][11][12] by using counter-rotating bicircular (CRB) pulses. The CRB field is a special double circular laser pulse consisting of counter-rotating fundamental waves and their second harmonics, whose rotational symmetry is threefold.…”