ABSTRACT Asymmetric electromagnetic (EM) mode conversion is a fundamental requirement for photonic devices such as filters and logic elements. We demonstrate strong reciprocal directional wave transport in an asymmetric photonic crystal (PhC). The system is linear, passive, time‐independent, and obeys Lorentz reciprocity. A semi‐asymmetric square‐lattice PhC composed of alumina rods, where the broken unit‐cell mirror symmetry along vertical and horizontal directions produces direction‐dependent modal coupling. Full‐wave simulations reveal pronounced unidirectional transport at the resonance frequency (5.765 GHz), quantified by a stopping factor (SF) of −23 dB and an insertion loss of 7 dB. An effective three‐site tight‐binding Hamiltonian is constructed, and its eigen frequencies and eigen vectors accurately reproduce the observed reciprocal directional transport response. Specifically, the resonance responsible for isolation and the SF of the numerical simulation are well‐matched with the analytical formalism. Experimental validation using a 10 × 10 PhC fabricated using alumina rods (99% Al 2 O 3 ) demonstrates near‐perfect agreement with the numerical results. To further demonstrate the potential of the designed asymmetric PhC array, a directional sensor is modeled, and its frequency and amplitude sensitivities are 0.5 MHz/RIU and 0.1 dB/RIU. These findings establish a connection between structural asymmetry and macroscopic transport behavior, advantageous for implementing unidirectional photonic components for interdisciplinary photonic applications.
Barkathulla et al. (Tue,) studied this question.
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