Optical device switches light 10,000x faster than silicon transistors

Researchers at the University of Oldenburg in Germany have developed an ultra-fast optical switch made from a nanostructured "active metamaterial" combining ultra-thin silver nano-slit arrays with a monolayer of the semiconductor tungsten disulphide. This hybrid structure can control light on femtosecond timescales—quadrillionths of a second—making it approximately 10,000 times faster than conventional silicon-based electronic transistors. The device operates by briefly storing incoming light in a hybrid quantum state called an exciton-plasmon polariton, which couples light and matter properties and allows strong interaction with electron-hole pairs (excitons) on the semiconductor surface. Using external laser pulses, the researchers were able to modulate the reflectivity of the device by up to 10 percent within about 70 femtoseconds, effectively switching the light signal at unprecedented speeds. The team employed two-dimensional electronic spectroscopy (2DES) to observe these ultrafast quantum interactions with high temporal