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High-harmonic generation (HHG) in solids has been touted as a way to probe ultrafast dynamics and crystal symmetries in condensed matter systems. Here, we investigate the polarization properties of high-order harmonics generated in…
Nonlinear optical materials of atomic thickness--such as non-centrosymmetric 2H transition metal dichalcogenide monolayers--have a second order nonlinear susceptibility ($\chi^{(2)}$) whose intensity can be tuned by strain. However, whether…
High-harmonic generation (HHG) in two-dimensional materials offers a compelling route toward compact extreme ultraviolet sources and probing electron dynamics on the attosecond scale. However, achieving precise control over the emission and…
Phosphorene, a well-studied 2D allotrope of phosphorus, features unique properties such as widely tunable bandgap, high carrier mobility, and remarkable intrinsic in-plane anisotropy. Utilizing these structural and electronic properties, we…
We report on experimental investigation of nonperturbative high harmonic generation (HHG) in monolayer MoS2 in the ultraviolet spectral region driven by mid-infrared light. We study how the HHG is influenced by pre-excitation of the…
We study strong-field driven ultrafast dynamics and high-harmonic generation (HHG) in monolayer 2H-NbSe$_2$ and compare them with those of monolayer 2H-MoS$_2$ by solving the multiband reduced-density-matrix equations including…
Due to the distinguished properties offered by different structural phases of monolayer MoS2, phase engineering design are urgently required for achieving switchable structural phase. Strain engineering is widely accepted as a clean and…
Solids in an intense laser field show high-harmonic generation (HHG), which can provide information on carrier dynamics and band structures in weakly correlated systems. In strongly correlated systems, a laser field can induce a transition…
Dynamic second-order nonlinear susceptibilities, $\chi^{(2)}(2\omega,\omega,\omega)\equiv \chi^{(2)}(\omega)$, are calculated here within a fully first-principles scheme for monolayered molybdenum dichalcogenides, $2H$-MoX$_2$ (X=S,Se,Te).…
High-order harmonic generation (HHG) is a fundamental process which can be simplified as the production of high energetic photons from a material subjected to a strong driving laser field. This highly nonlinear optical process contains rich…
Solid-state high-order harmonic generation (HHG) presents unique features different from gases.Whereas the gaseous harmonics driven by counter-rotating bicircular (CRB) pulse universally peak at a "magic" field ratio approximately…
High harmonic generation (HHG) is a powerful probe of electron dynamics on attosecond to femtosecond timescales and has been successfully used to detect electronic and structural changes in solid-state quantum materials, including…
Two-dimensional (2D) materials with zero band gap exhibit remarkable electronic properties with wide tunability. High harmonic generation (HHG) in such materials offers unique platforms to develop novel optoelectronic devices at nanoscale,…
We report the influence of uniaxial tensile mechanical strain in the range 0-2.2% on the phonon spectra and bandstructures of monolayer and bilayer molybdenum disulfide (MoS2) two-dimensional crystals. First, we employ Raman spectroscopy to…
High harmonic generation (HHG) in solids has recently emerged as a powerful all-optical approach for probing material properties and ultrafast electron dynamics in quantum systems. It has been widely applied for studying two-dimensional and…
Second harmonic generation (SHG) is a non-linear optical process, where two photons coherently combine into one photon of twice their energy. Efficient SHG occurs for crystals with broken inversion symmetry, such as transition metal…
The recently discovered two-dimensional (2D) layered semiconductor MoSi2N4 has aroused great interest due to its unique 2D material characteristics. In this Letter, we found that differences in the structural details for MoSi2N4 may lead to…
In transition metal dichalcogenides (TMDCs), charge carriers have spin, pseudospin, and valley degrees of freedom associated with magnetic moments. The monolayers and bilayers of the TMDCs, in particular, MoS$_2$, lead strong couplings…
Two-dimensional materials such as transitional metal dichalcogenides exhibit unique optical and electrical properties. Here we report on the varying optical properties of CVD grown MoS2 monolayer flakes with different shapes. In particular,…
An analytic description of high harmonic generation (HHG) in solids induced by intense low-frequency pulses is presented within an adiabatic approach, which treats laser-matter interactions nonperturbatively. We derive the analytical…