High-performance microprocessors that harness photons rather than electrons promise to make computers up to a thousand times more efficient because electrons typically move at a low fraction of the speed of light. Problem: scaling down conventional electronic microprocessors is easy; doing the same with photonic components is hard because of the difficulty of getting light to turn corners. So scientists have turned to plasmonic components, which take advantage of the unique oscillating interactions of photons and electrons on the surface of metal.
Unfortunately, plasmonic components get too hot and you can’t just throw a fan on them. You need a cooling system that works on the scale of the photonic chip’s key features, less than a billionth of a meter in size. It’s one reason why many don’t consider fully light-based transistors a practical possibility for decades. It’s also why there is such excitement around a new paper by a team of Russian researchers showing a new method for cooling photonic components.
Optoelectronics are already emerging as a key research area for companies like Oracle and IBM. IBM’s Zurich-based photonics research group explains why: “Based on the current trend toward ever more powerful high-end computers, it is expected that supercomputers comprising nearly 100 million computation modules and featuring exaflop performance rates, i.e. one trillion (1018) operations per second, will be developed within that timeframe. Without improved energy efficiency on all levels, however, a future supercomputer would require its own dedicated power plant.”
It’s no wonder the Defense Advanced Research Projects Agency, or DARPA, has also funded optoelectronic research.
What’s so hard about scaling down optoelectronic components? In order for your on-chip optoelectronic components to work with bulk light waves, it would have to be enormous, which destroys the efficiency gain you were going for. You can confine light to smaller dimensions by converting it into surface plasmon polaritons, electromagnetic waves that propagate on the surface of a the chip’s metal and dielectric layers. But these can cause overheating, a lot of overheating: temperature increases of 100 Kelvin, a big enough temperature differential to take frozen water to boiling. The Russian researchers claim that their method, published this week in the journal ACS Photonics, can limit temperature increases to within just a few degrees K.
Such components “will give a possibility to create high-performance computers and analyze information many orders of magnitude faster than it is done today. However, in order to design computers based on these microprocessors (ranging from onboard computer for fighter aircrafts to exascale and zettascale supercomputers, which are required for data analysis and simulation of combat situations), the microprocessors should be efficiently cooled,” Dmitry Fedyanin, one of the authors of the paper, said in an email.
Fedyanin discusses the research in the cheery video below.