One-way optical transmission in silicon grating-photonic crystal structures.

One-way optical transmission through a composite structure of grating-photonic crystal (PC) is presented. This unidirectional transportation property originates from the diffraction of grating to change the direction of light incident into the PC from pseudobandgaps to passbands of the PC. Numerical simulation shows that a light beam in a certain range of frequencies can transmit the composite structure when it is incident from the grating interface but is completely reflected by the structure when it is incident from the PC interface, which is further verified experimentally. The present structure may provide another more compact way for designing on-chip optical diode-like integrated devices.