An optical transistor that uses one laser beam to control another could form the heart of a future generation of ultrafast light-based computers, say Swiss researchers. Conventional computers are based on transistors, which allow one electrode to control the current moving through the device and are combined to form logic gates and processors. The new component achieves the same thing, but for laser beams, not electric currents. A green laser beam is used to control the power of an orange laser beam passing through the device.

This offers another possible route to light-based rather than electronic, computing. Such "photonic" computing is desirable because components using optical fibres carrying light could be much faster than those using wires to carry electricity.

However, previous attempts to make optical transistors for such circuits only produced very weak effects. The new device could change that.