But there is a big difference between communicating data and computing with it. And this is where analog optical approaches hit a roadblock. Conventional computers are based on transistors, which are highly nonlinear circuit elements—meaning that their outputs aren’t just proportional to their inputs, at least when used for computing. Nonlinearity is what lets transistors switch on and off, allowing them to be fashioned into logic gates. This switching is easy to accomplish with electronics, for which nonlinearities are a dime a dozen. But photons follow Maxwell’s equations, which are annoyingly linear, meaning that the output of an optical device is typically proportional to its inputs.Ryan Hamerly, “The future of deep learning is photonic” at IEEE Spectrum
That’s one reason electronics researchers started looking at photonics: “the creation, manipulation and detection of light in the service of practical applications where the particle nature of light is important” (Synopsys.) Light can be both a wave and a particle.
Hamerly goes on to note reasons why using light for computing will catch on:
Many of the concepts in analog optical computing are decades old. Some even predate silicon computers. Schemes for optical matrix multiplication, and even for optical neural networks, were first demonstrated in the 1970s. But this approach didn’t catch on. Will this time be different? Possibly, for three reasons.
First, deep learning is genuinely useful now, not just an academic curiosity. Second, we can’t rely on Moore’s Law alone to continue improving electronics. And finally, we have a new technology that was not available to earlier generations: integrated photonics. These factors suggest that optical neural networks will arrive for real this time—and the future of such computations may indeed be photonic.Ryan Hamerly, “The future of deep learning is photonic” at IEEE Spectrum
Here’s a simple explanation from 2018:
It looks promising but perhaps it is too soon to tell whether it ismay not be on the near horizon.
You may also wish to read:
Google Glass Inventor to Speak at COSM, October 25, 2019. Babak Parviz, now an Amazon vice-president, is keenly interested in services for the swelling aged population worldwide. His work has included photonics.
and, more exotically,
Quantum physicist: Aliens may communicate by starlight
Terry Rudolph of Imperial College, London, argues that they may have evolved so as to take advantage of quantum mechanics via photonics more easily than we can. Photonics is a form of communication that takes advantage of the fact that light moves faster than electricity.