Dynamically controlled nanofocusing metalens based on graphene-loaded aperiodic silica grating arrays

A new plasmonic nanofocusing metalens based on aperiodic silica grating arrays was designed and investigated. Assisted by the graphene surface plasmon, the infrared polarized light can be focused in a nanospot with a dynamically controlled focal length by varying the dielectric strip width or the graphene Fermi level E-f. For instance, with lambda(0) = 8 mu m and E-f at 0.3, 0.6 and 0.9 eV, focal lengths of 4.5, 3.8 and 3.5 mu m with its corresponding FWHM of 64, 232 and 320 nm, respectively, can be realized. The variation of the focusing efficiency with respect to the incident wavelength and the Fermi level were also investigated. The results of theoretical analysis based on light differential equations agree well with the finite element analysis simulation, which further validate the model. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

A new plasmonic nanofocusing metalens based on aperiodic silica grating arrays has been designed and investigated. By utilizing graphene surface plasmon, the infrared polarized light can be focused in a nanospot with a dynamically controlled focal length. The study also analyzes the variation of focusing efficiency with incident wavelength and Fermi level.