Permittivity acquisition of plasmonic materials at epsilon near zero wavelengths

Due to their unique optical properties, plasmonic materials are widely used in nonlinear optics, nanophotonics, optoelectronics, photocatalysis, biosensing, information storage, etc. Researchers usually need to know the detailed permittivity behavior at the vicinity of surface plasmons’ excitation wavelengths, which in turn are located near the zero points of the real part of the permittivity called epsilon-near-zero (ENZ). We hereby introduce a spectral fitting method to quickly obtain the materials' permittivity at the ENZ region and summarize the experiences of selecting dispersion models and optimizing model parameters. Specifically, we have made a detailed description of the optical constant fitting process for a series of plasmonic materials such as heavily doped semiconductors, transparent conductive oxides, organic conductive materials, two-dimensional materials, and sandwiched composites. Hopefully, to provide specific data and theoretical support for researchers in the field of photoelectric properties of plasmonic materials.