Long-wave infrared to short-wave infrared upconversion through sum-frequency generation in a silicon symmetric metasurface integrated with two-dimensional material

Optical resonances supported by subwavelength nanostructures have significant local-field enhancement effects and are important in the field of nanophotonics such as photoemission and nonlinear optics. In this paper, silicon metasurface with toroidal dipole resonance in the short-wave infrared band is investigated. The formation and properties of the high-quality toroidal dipole resonance are analyzed in detail by the near-and far-field analysis, and the electromagnetic multipole decomposition methods in the metasurface with different structural param-eters. In addition, a layer of two-dimensional nonlinear material GaSe is combined with the silicon metasurface, to enhance the long-wave infrared to short-wave infrared upconversion by the nonlinear sum-frequency gen-eration (SFG) process through toroidal dipole resonance. The upconversion efficiency in the GaSe/ silicon metasurface bilayer system is nearly a thousand times more than that in the GaSe/planar silicon bilayer system, indicating the effectiveness of the toroidal dipole resonance generated by the metasurface. This method provides a feasible and viable strategy for upconverting mid-wave infrared or long-wave infrared to near-or short-wave infrared by the nonlinear process induced by the metasurface, which is potentially very attractive for the sensing and imaging of long-wavelength photons that beyond the capability of mature silicon/germinium detectors.