Plasmonic ultra-broadband polarizers based on Ag nano wire-slit arrays

We propose ultra-broadband reflective and absorptive polarizers in the visible range using multi-scaled Ag nano wire-slit arrays. The nano arrays can be tuned from reflective to absorptive by incorporating Ag wires/strips with different lengths/widths. The ultra-broadband nature of the absorptive array, with averaged absorption as high as ~80%, is due to the collective excitations of plasmonic resonances in the Ag wires/strips with different length scales. The Ag nano wire-slit arrays are realized experimentally by using a simple two-times shadowing vapor deposition method. They exhibit broadband transmission difference, in good agreement with simulations. The multi-scaled Ag nano wire-slit array has potential applications as broadband linear polarizers and anti-reflective materials in both optics and photovoltaics.