We report on the resonant properties of platinum dipole antennas fabricated on a silicon-rich-oxinitride thin film that exhibits significant absorption in the mid-infrared of the electromagnetic spectrum (λ-1≈1100 cm-1). A nonlinear scaling between the resonant wavelength and the antenna length has been found and quantitatively confirmed by full-field electromagnetic simulations. The resonant wavelength increases linearly with antenna length for small lengths and tends to saturate for large ones (length > 4 μm). This saturation effect is attributed to the coupling of a geometrical antenna resonance and an absorption resonance of the substrate material.
- Physics and Astronomy (miscellaneous)