PORTLAND, Ore. -- A thin-film optical diode demonstrated recently at the Massachusetts Institute of Technology can be integrated onto a silicon photonic chip along with lasers and waveguides. Previously, a separate, discrete device was required.
Called a "diode for light" by its creator, MIT professor Caroline Ross, the device creates a one-way street for photons in the same way an electric diode directs a current flow in only one direction. Optical diodes will be useful for future photonic chips that would eliminate the need for translating optical into electrical signals and back again in order to perform switching and signal processing functions.
|MIT engineering professor Caroline Ross has created the world's first silicon optical diode.|
Using a garnet material, which has a different index of refraction depending on which way light is flowing through it, MIT researchers demonstrated the passing of optical signals in one direction. Those signals were then diverted into a loop when traveling in the opposite direction.
Garnet, a material that is both transparent and magnetic, is more difficult than silicon to fabricate on CMOS chips. Nevertheless, Ross and colleagues demonstrated that thin-films of garnet could be deposited on silicon using standard processing steps.
Funding for the research was provided by the National Science Foundation.