On Tuesday, Intel demonstrated the world’s first practical data connection using silicon photonics – a 50 gigabit per second optical data connection built around an electrically pumped hybrid silicon laser. They achieved the 50 gigabit/s data rate by multiplexing 4 12.5 gigabit/s wavelengths into one fiber – wavelength division multiplexing. Intel dubbed its demo the “50G Silicon Photonics Link.”
Fiber optic data transmission isn’t anything new – it’s the core of what makes the internet as we know it today possible. What makes Intel’s demonstration unique is that they’ve fabricated the laser primarily out of a low-cost, mass-produceable, highly understood material – silicon.
For years, chip designers and optical scientists alike have dreamt about the possibilities of merging traditional microelectronics and photonics. Superficially, one would expect it to be easy – after all, both fundamentally deal with electromagnetic waves, just at different frequencies (MHz and GHz for microelectronics, THz for optics).
On one side, microelectronics deals with integrated circuits and components such as transistors, copper wires, and the massively understood and employed CMOS manufacturing process. It’s the backbone of microprocessors, and at the core of conventional computing today. Conversely, photonics employs – true to its name – photons, the basic unit of light. Silicon photonics is the use of optical systems that use silicon as the primary optical medium, instead of other more expensive optical materials. Eventually, photonics has the potential to supplant microelectronics with optical analogues of traditional electrical components – but that’s decades away.
Until recently, successfully integrating the two was a complex balance of manufacturing and leveraging photonics only when it was feasible. Material constraints have made photonics effective primarily as a long haul means of getting data from point to point. To a larger extent, this has made sense because copper traces on motherboards have been fast enough, but we’re getting closer and closer to the limit.