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Abstract Asymmetric light transmission components, such as optical diodes, have attracted great interest for the capability of unidirectional light propagation. Highly desirable key performances of above devices are high unidirectionality, wide operational bandwidth and small scale. In this paper, we present an efficient design for asymmetric light transmission components in two-dimensional air-hole photonic crystals based on silicon. Through introducing tapered structure on the heterostructure interface, the forward transmittance of the optimized photonic crystal structure has increased greatly than that of the original structure almost within the entire frequency range (0.18–0.261 c/a). Meanwhile, the peak transmittance for the optimized structure increases by about 68.3%, varying from 28.4% to 47.8%. Moreover, the designed optical devices can effectively function as unidirectional equal-beam splitters, and multiple functions can be achieved synchronously in only one structure, which are important in the complex optical integrated circuits. Highlights • Asymmetric light transmission components based on PC heterointerface optimization are realized in broad bandwidths. • The optimized PC structure can effectively function as unidirectional equal-beam splitters. • Multiple functions can be achieved synchronously in only one PC structure. [ABSTRACT FROM AUTHOR]

Highlights: [•] Frequency tuned air-slot mode-gap nanocavities are obtained. [•] Frequency can be continuously tuned almost covering the entire mode gap region. [•] The cavity’s resonant frequency is very sensitive to the shape alteration. [ABSTRACT FROM AUTHOR]