A novel plasmonic nanofilter based on complementary H-fractal shape components

We propose a novel infrared nanofilter of localized enhanced field with multiband resonant frequencies. Compared to the resonant wavelength, the structure size is very subwavelength. We establish the effective medium theory to illustrate the light field distribution of the fractals. The loss factor is used to retrieve relative permittivity which is utilized to reproduce of reflection and transmission coefficients in the effective homogeneous plate. By bringing the inevitable metal loss to advantage, the enhanced factor of the field in the filter can reach a factor of 16 times amplification.