Fig. 1. Schematic diagram of the proposed three-layered Au-SiO₂-Au thin film structure

Fig. 2. Simulated absorption spectra of MDM structure with thicknesses d₁, d₂ and d₃ of 100 nm, 580 nm, and 30 nm, respectively

Fig. 3. Simulated electric field distribution in the cavity when the FP mode resonance was formed

Fig. 4. Simulated results of absorption at different thicknesses of the top Au layer. (a) Simulated absorption curves of single Au film with various thicknesses. (b) Simulated absorption curves of MDM three-layer structure with various thicknesses of the top Au layers, when the thickness of the intermediate silicon oxide is fixed at 125 nm

Fig. 5. (a) Schematic diagram of incident light passing through a single layer film. (b) Schematic diagram of equivalent interface of single layer

Fig. 6. (a) Reflection and (b) absorption spectra of MDM structure simulated by FDTD method with various SiO₂ thicknesses of 85 nm, 105 nm, 125 nm, 155 nm, 175 nm, respectively

Fig. 7. Simulated electric field distributions in the cavity at the non-resonant and resonant wavelengths, with various three-layer thicknesses of 100 nm, 125 nm and 30 nm

Fig. 8. Simulated absorption distribution at the resonance wavelength of 543 nm with an intermediate layer of 125 nm

Fig. 9. The calculated total Ohmic loss at the non-resonant and resonant wavelength when the three layers thicknesses are 100 nm, 125 nm and 30 nm, respectively

Fig. 10. Comparison of simulated and experimentally measured absorption curves with an intermediate silicon oxide layer thickness of 580 nm

Fig. 11. Comparison of the simulated and experimentally measured absorption spectra of the five samples