A new optical switch is, at 1 trillion operations per second, between 100 and 1,000 times faster than today’s leading commercial electronic transistors. The research may lead to a new generation of computers based on light instead of electricity.
The new device relies on a 35-nanometer-wide organic semiconductor polymer film sandwiched between two highly reflective mirrors. The result is a microscopic cavity designed to keep incoming light trapped inside for as long as possible to help it couple with the cavity’s material.
Two lasers help operate the optical switch — a bright pump laser and a very weak seed laser. When the pump laser shines on the microcavity, its photons can couple strongly with excitons (electrons bound to their positively charged counterparts, holes) within the cavity’s material. This can give rise to short-lived quasiparticles known as exciton-polaritons.
The cluster of exciton-polaritons can form so-called Bose-Einstein condensates, collections of particles that each behave like a single atom. The light from the seed beam could switch this condensate between two measurable states that serve as zero and one. The new device can switch using as little as one photon of input on average.