Abstract

Over the past few decades, the study of bound states in the continuum (BICs), their formation, and properties has attracted a lot of attention, especially in optics and photonics. It is particularly noticeable that most of these investigations are based on symmetric systems. In this article, we study the formation of bound states in the continuum in electronic and photonic transport systems consisting of crossbar junctions formed by one-dimensional waveguides, considering asymmetric junctions with commensurable lengths for the upper and lower arms. These BICs in an asymmetric system go beyond the symmetry-protected paradigm. We also study how BICs form in linear junction arrays as a function of the distance between consecutive junctions and their commensurability with the upper and lower arms. New commensurability conditions in the array's central section also give rise to Fabry-P & eacute;rot-type BICs. We solve the Helmholtz equation for the crossbar junctions and calculate the transmission probability, local density of states in the intersections, and quality factor. The presence of quasi-BICs is reflected in the transmission probability as a sharp resonance in the middle of a symmetric Fano resonance, along with Dirac delta-functions in the probability density and divergence in the quality factors.