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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]

The splitting properties are investigated in two dimensional silicon photonic crystals by adjusting the interface of the structure. Introducing elliptical air holes with optimized parameters on the heterointerface, the forward transmittance is significantly improved in a wide frequency range. Correspondingly, the unidirectional two-beam splitter is realized and the relative light intensities of each beam can be continuously adjusted by modulating the area ratio (AR) of elliptical air holes. Furthermore, the output beams can be changed into three and five beams by alternately introducing elliptical air holes on the monolayer output interface. Not only the forward light intensities of each beam can be continuously adjusted, but also the reverse can be tuned simultaneously by modulating the shape of elliptical air holes. Particularly, the light transmission behaviors along two opposite directions are significantly different. Moreover, the elliptical-shaped air holes have more structural freedoms and increase the design flexibility of the devices. The performance of the splitter is found to be very encouraging in the complex photonic integrated circuits. [ABSTRACT FROM AUTHOR]