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Ultrafast Light Switches Use Atomically Thin Semiconductors for Rapid Optical Control

Researchers at the University of Oldenburg have created a hybrid nanostructure of silver and a monolayer tungsten disulfide that acts as an ultrafast optical switch, changing its reflectivity within 70 femtoseconds. The device, described in Nature Nanotechnology, demonstrates a 10 % modulation of reflected light using femtosecond laser pulses, a speed roughly 10,000 times faster than conventional electronic transistors. By storing light in an exciton‑plasmon polariton state, the switch can be toggled on a timescale previously inaccessible to optical components. The breakthrough points toward optical transistors for next‑generation data processing.