Researchers see photonic chips being created from silicon

In many communication systems, data travels via light beams transmitted through optical fibres.

Once the optical signal arrives at its destination, it is converted to electronic form, processed through electronic circuits and then converted back to light using a laser. The new device could eliminate those extra electronic-conversion steps, allowing the light signal to be processed directly.

The component is a ‘diode for light’, said Caroline Ross, Toyota professor of materials science and engineering at MIT, who is co-author of a paper reporting the device that was published recently online in the journal Nature Photonics.

According to a statement from MIT, it is analogous to an electronic diode, a device that allows an electric current to flow in one direction but blocks it from going the other way; in this case, it creates a one-way street for light, rather than electricity.

This is essential, Ross explained, because without such a device, stray reflections could destabilise the lasers used to produce the optical signals and reduce the efficiency of the transmission. Currently, an isolator is used to perform this function, but the new system would allow this function to be part of the same chip that carries out other signal-processing tasks.