Researchers at MIT believe they’ve taken an important step in developing the next generation of silicon chips. The photonic version would use light beams rather than electrons, greatly increasing speed and efficiency as well as boosting communications.
The aim of the research was to avoid the current wasteful process by which data transmitted by fiber optic cable must be converted to electronic form for use in electronic circuits, only to then be converted back to a laser signal.
While it was already technically possible to simply process and pass the light signals straight through to the laser, there was a risk that stray reflections could make the transmission less efficient. It’s possible to limit this risk by using a device that only allows light to pass in one direction, similar to an electrical diode.
At the moment that’s done by a standalone device, but the researchers wanted to find a way to build it directly onto a silicon chip, saving space and increasing efficiency. That requires a material that is both magnetic and transparent, in this case garnet, a mineral more commonly used for jewelery and as an abrasive. Unlike some materials, the angle at which it reflects light depends on the angle of the incoming beam, making it suitable for the “diode” role.
Though using garnet on silicon chips has previously proven difficult, the MIT team were able to come up with a suitably efficient design, which meant a thin film of the material would be enough. The design involves a semi-loop such that any light traveling in the “wrong” direction is simply sent back where it came from.
While the researchers were aiming to solve a specific problem, their solution means it’s at least theoretical possible to make chips, and in turn circuits, that are entirely optical rather than electrical. As light travels faster than electrons (and indeed everything), it could make for quicker circuits. It’s also possible that, in the same way as a fiber optic cable can carry phone, TV, and internet signals through the same “pipe” simultaneously, such circuits could carry multiple streams of data at once.