Wideband high-contrast optical diode and unidirectional beam splitters via near-infrared metallic photonic crystals

A novel nanoscale all-optical photonic crystal diode consisting of rectangular and square metals immersed in silicon is reported. This wideband high-contrast diode based on the self-collimation behavior can confine the light beams travel along a certain direction. So it works well needless of the input and output waveguides and is more feasible to combine with other functional devices in the complex integrated optical circuits. And through a simple design of two photonic crystals' interface, unidirectional beam splitters owing to the directional band gap can also be obtained.