Design of high-efficiency small-size passive all-optical diodes based on photonic crystal and graphene

Abstract

Light propagation in an asymmetric multilayered structure composed of a linear defective photonic crystal and nonlinear graphene layer is theoretically investigated. A (BA)4/graphene/(AB)4(AABB)4 structure with a slight perturbation in the (AABB)4 part can provide non-reciprocal transmission to achieve an optical diode. This structure was optimized in order to have a low-operation input intensity, high-contrast, small-size all-optical diode without an additional pump signal. In this work, four different passive all-optical diodes are presented. The best contrast ratio is 6.3, and the minimum operation input intensity for diode action is 2.7×10−3 MWcm2. This structure gives an all-optical diode with a smaller size and higher efficiency in comparison to previous works.