Abstract

Exceptional points (EPs) are the branch point singularities, where two coupled eigenvalues and the associated eigenvectors simultaneously coalesce. Lately, various open photonic systems hosting EPs have attracted attention to meet different applications in diverse photonic structures, where various vivid applications have been explored [1-3]. In this work, using the framework of a 1D photonic bandgap waveguide (WG), we implement two individual complementary active perturbations in terms of an unbalanced gain-loss profile in the designed waveguides to host a pair of conjugate EP2s (EP2 & EP2*) between two coupled TE modes (TE₀ and TE₁). The dynamical encirclements of the EP2 and EP2* with the length-dependent gain-loss distribution establish particularly opposite robust chiral output response (to differentiate, we can term as chiral and reverse chiral responses) of two complementary 1D photonic bandgap waveguide designs. We propose the design of a 1D

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