Modes selecting in all-dielectric resonators with different shapes

Left-handed behaviors of all-dielectric resonators with different cross section shapes have been studied. It is shown that simultaneous negative permittivity and permeability can be realized at either the first or the second resonant modes governed by the shape of the cross section. For a dielectric resonator with rectangular cross section of 0.5 mm times 2 mm, the second resonant mode resulting from the electric and magnetic dipole moments are expected to give rise to simultaneous negative effective permittivity and permeability. Whereas, simultaneous negative effective permittivity and permeability can be achieved at the first resonant mode for a dielectric resonator with a square cross section of 1 mm times 1 mm.