Analysis of metallic slotted micromirrors using modal decomposition and multiple reflections

Micromirrors are essential elements in many photonic systems. The state-of-the-art technology provides micromachining of different types of micromirrors such as Bragg, metallized, and slotted metallic mirrors. The slotted metallic mirrors are thought to overcome some of the drawbacks of the other types that include limited bandwidth, sensitivity to fabrication tolerance, and dielectric material absorption. We propose a model that accounts for the slit thickness and width, incident light profile and polarization in addition to the multiple reflections inside the slit using modal decomposition. The model results are compared to finite-difference–time domain simulations and a good matching is obtained. The model successfully quantifies the transmission below cutoff in the TE polarization for perfectly conducting metallic boundaries. The model also quantifies the Fabry–Pérot-like resonances in the transmission of TM polarized light.