Tailoring Dispersion Property and Anisotropy of Second-Harmonic Generation by Strain Engineering in Monolayer GeSe

Strain engineering on the dispersion property and anisotropy of second-harmonic generation (SHG) is crucial for advancing the understanding and development of nonlinear optical materials and devices with tailored light-matter interactions. Herein, we theoretically demonstrate the intricate relationship between strain engineering and modulation of SHG in ferroic monolayer GeSe. The bandgap tends to expand upon the application of strain, be it uniaxial or biaxial in nature. It is important to note that neither uniaxial nor biaxial strains induce the emergence of novel nonzero second-order nonlinear optical susceptibility elements; they do exert a significant influence on the pre-existing elements. This alteration has a consequential effect on the SHG process. Additionally, the characteristic peak of the second-order nonlinear coefficient element d11 undergoes a significant shift with the increase in strain, attributed to the variation in interband transition contributions induced by strain. The imposition of strain, whether uniaxial or biaxial, can markedly alter the dispersion and anisotropic properties of the nonlinear optical response. These modifications are observed to be contingent upon factors such as the wavelength, azimuthal angle, polarization angle, and incidence angle. These findings provide valuable insights into the design and optimization of 2D materials for optoelectronic applications, highlighting the potential of strain engineering as a powerful tool for tailoring nonlinear optical properties.