Electromagnetic dipole resonant characteristics of all-dielectric one dimensional grating in terahertz region

Mie-type magnetic and electric resonances in an all-dielectric one-dimensional grating are theoretically demonstrated in terahertz region. It is found that strong polarization-sensitivity and frequency-selection behaviors of resonances can be excited in all dielectric subwavelength grating structure. This all dielectric grating with less absorption loss can be carefully designed as broadband reflectors and polarization beam splitters. The coupling effects of the array silicon pillar and the electromagnetic field distribution were numerically calculated by use of finite element method. The effective constitutive parameters of subwavelength grating, including in the effective refractive index, effective permittivity, effective permeability, and effective impedance, can be extracted by using the standard retrieval method of inversion algorithm. Magnetic and electric Mie resonances can be revealed by enhanced effective parameters at resonant frequencies.