Toyota Professor of Materials Science and Engineering Caroline Ross (via MIT & Allegra Boverman)
Developments in photonics show the near-future possibility of a complete replacement in digital technology. Fibre optics has been the backbone of communication for decades. Light based interconnects are poised to replace wires at the chip level. Now, researchers at MIT have conquered an important hurdle when it comes to creating an all-optical chip, the diode.
Currently, light will carry data to an electrical circuit. The data will then get processed and reconverted back into light. The team at MIT, lead by Toyota Professor of Materials Science and Engineering Caroline Ross, wanted to eliminate this step and place it onboard the same communication IC. The "diode for light" was born.
The search for a material that could act like a diode brought the team to the mineral, garnet. The index of refraction in the gemstone allows light to travel in one direction, but refracts it sharply in the other. A thin layer of garnet was deposited on top of a silicon-based chip in the light-transmitting paths. The light passed through freely on the IC, but in the opposite direction, the light was redirected into a "loop" on the IC, a dampening area.
Ross explained, "It simplifies making an all-optical chip. [IC using this technology can be designed] just like an integrated-circuit person can design a whole microprocessor. Now, you can do an integrated optical circuit.”
This diode for light can be created using current wide-spread silicon manufacturing equipment. Ross elaborated, "A silicon platform is what you want to use... there’s a huge infrastructure for silicon processing. Everyone knows how to process silicon. That means they can set about developing the chip without having to worry about new fabrication techniques.”
Moving towards photonic design over electronics has many benefits, from less power for transmission, longer distances, to the physical weight. From my perspective, the greatest of all is the immunity to electromagnetic interference. Imagine not having to worry about where to place a microcontroller in relation to a transmission line. What a whole new world that will be.
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