As computers’ processing speeds grow ever faster, they are approaching the limits of their electronic components. More speed requires additional power and smaller, denser chips, but miniaturization inhibits heat dissipation. Fiber-optic cables already transmit information encoded in light faster and more reliably than electrical cables can carry electronic signals. If computers also processed information as light instead of electronically, they could boost computational speed and mitigate the excess heat generation that besets electronic circuits as they become faster and smaller.

Switching from electrical to optical computing has other clear advantages.1 In addition to faster signal propagation and less heat generation, optical signal processing is also inherently parallel. To understand why, consider imaging with a lens. The light intensity in the back focal plane is the spatial Fourier transform of the original signal. Performing the same Fourier transform electronically would require the function value at each point to be calculated sequentially, but with optics all points are evaluated simultaneously.
Researchers are developing materials and devices that may one day lead to practical optical computing technologies. Many of them manipulate light in the same way that switches and logic gates direct electronic signals. Those switches and gates would then be assembled into larger, multifunctional networks. But there’s no reason the strategies used in light-based computers have to mimic those of conventional computers, and other approaches target devices designed to perform specialized functions in ways that could surpass electronics.

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