Broadband transparency by graded metamaterials.

In the quasistatic limit, Rayleigh scattering is investigated for a graded spherical metamaterial when the wavelength of light is larger than the particle diameter. As a theoretical model, we have exactly derived the dipole factor of the Rayleigh scattering electric field induced by the graded sphere metamaterial, whose permittivity is given by the graded Drude model. Our results show that the amplitude of scattering field can be controlled and remains very small over a broad frequency band by tuning the gradation profiles of particle permittivity. This implies that a broadband transparency of electric field is achieved by using graded metamaterials. Here, we offer a solvable example of very small Rayleigh scattering in a broad frequency band. [ABSTRACT FROM AUTHOR]