Analytical Design of Practical-Thickness Slab Devices Supporting Bound States in the Continuum

The use of bound states in the continuum (BICs) in photonic crystal slabs, which are Bloch eigenstates with zero linewidth and infinite lifetimes, facilitates the development of microwave resonators with ultrahigh quality factors and enhances antenna performance by enabling strong field confinement and radiation control. In this paper, we propose a method to design devices that sustain BICs for microwave applications. This method relies on a theoretical framework initially developed for thin photonic slabs. The objective of this study is to demonstrate that increasing the slab thickness, starting from a thin configuration, preserves the BIC properties of the device. This finding is significant for engineering microwave devices and antennas that support BICs while accommodating practical slab thicknesses that are not excessively small.