Resonant frequency and bandwidth of metamaterial emitters and absorbers predicted by an RLC circuit model

• Investigated geometric effect on wavelength-selective metamaterial thermal emitters and absorbers.
• Developed an RLC model for prediction of the resonance characteristics of magnetic polaritons.
• The RLC circuit model can predict the resonance frequency as well as the bandwidth of the emission/absorption peak.
• Used FDTD to obtain the electromagnetic field and power dissipation within metamaterial structures.
• The RLC circuit model agrees well with the FDTD simulation for both wire- and cross-patterned metamaterials.

Metamaterial thermal emitters and absorbers have been widely studied for different geometric patterns by exciting a variety of electromagnetic resonances. A resistor–inductor–capacitor (RLC) circuit model is developed to describe the magnetic resonances (i.e. magnetic polaritons) inside the structures. The RLC circuit model allows the prediction of not only the resonance frequency, but also the full width at half maximum and quality factor for various geometric patterns. The parameters predicted by the RLC model are compared with the finite-difference time-domain simulation. The magnetic field distribution and the power dissipation density profile are also used to justify the RLC circuit model. The geometric effects on the resonance characteristics are elucidated in the wire (or strip), cross, and square patterned metamaterial in the infrared region. This study will facilitate the design of metamaterial absorbers and emitters based on magnetic polaritons.