Analytical Circuit Modeling of Extraordinary Optical Transmission in 1D Slit Arrays with Cascaded Stepped Inhomogeneous Cores

• Presenting a fully analytical circuit model for EOT in 1D slit arrays with cascaded stepped and multilayer cores. • Achieving accurate over wide angles and frequencies up to twice Wood’s anomaly, with strong FEM agreement. • Providing resonance tuning, bandwidth expansion, and multi-band operation for imaging and communication. Optimizing the resonance spectra of periodic slit structures is crucial for leveraging Extraordinary Optical Transmission (EOT) across various applications, including terahertz communications and imaging. Engineering slit array structures with inhomogeneous(multilayer) core and internal stepped structures are essential to increase bandwidth, control number of spectral bands, reduce the structure thickness, and fine tune resonance frequencies. To efficiently predict the scattering behaviour of light through these mentioned complex slits a fully analytical circuit model is proposed, offering a computationally efficient alternative to intensive numerical methods. The reliability of the proposed circuit model is verified by analyzing various cascaded discontinuities and conducting comprehensive comparisons with Finite Element Method (FEM) simulations. These comparisons, which evaluate a frequency range up to twice the onset frequency of the first grating lobe across multiple incident angles, confirm the high accuracy of the circuit model relative to full-wave numerical methods. For an inhomogeneous core configuration, the model demonstrates near-perfect precision, yielding maximum frequency and amplitude errors of merely 0.06% and 0%, respectively, at the highest resonance, while drastically reducing computation time from over 12 minutes to just 2 seconds. Analysis of the transmission spectrum and magnetic field distribution of structures incorporating stepped internal features confirms their applicability to the design of selective frequency devices. The findings provide a computationally efficient design tool for periodic slit and hole structures, applicable from the microwave to beyond the infrared spectrum.