摘要
Triple mechanisms were employed to trap mid-infrared (mid-IR) rays within a semi-transparent SiO 2 film sandwiched between gold gratings and a gold substrate. Dimensions of four absorbers were explicitly determined using an LC (inductor-capacitor) circuit model considering the role transition of SiO 2 film. The film behaves as a capacitance and an inductance when the real part of relative electric permittivity for SiO 2 is positive and negative, respectively. At the normal incidence of transverse magnetic waves, every absorptance spectrum of absorbers showed a peak at wavelength λ = 10 μm due to the first mode excitation of magnetic polaritons (MP). At oblique incidence, the Berreman mode led to another peak at λ = 8 μm while its bandwidth was expanded with epsilon near zero mode excited by diffracted waves. The full-width-at-half-maximum of both peaks exceeded 0.6 μm thanks to the SiO 2 loss. Other minor absorptance peaks in the mid-IR were caused by variants of the same MP mode. © 2013 Optical Society of America.