Multimodal Semi-analytical Model for Bound States in the Continuum and Unidirectional Guided Resonances in a Photonic Crystal

Recent attention has been directed towards optical bound states in the continuum (BICs) within photonic crystal slabs. Unidirectional guided resonances (UGRs) have also garnered interest, an associated phenomenon that involves intentionally broken symmetry and resulting in directional leakage. This study introduces a microscopic semi-analytical model to better understand these resonances. Building on a multimodal interference method used for BIC exploration, our approach extends to investigating UGRs, providing valuable insights into their distinct properties. Using this model, we aim to contribute to the design and comprehension of BICs and UGRs in photonic crystal slabs.