High-speed internet uses light to quickly and reliably transmit large amounts of data through fiber-optic cables, but currently, light signals hit a bottleneck when data processing is necessary. For that, they must convert into electrical signals for processing before further transmission.

Circularly Polarized Light Switching a device called an all-optical switch could instead use light to control other light signals without the need for electrical conversion, saving both time and energy in fiber-optic communication.

A University of Michigan-led research team demonstrated an ultrafast all-optical switch by pulsing circularly polarized light, which twists like a helix, through an optical cavity lined with an ultrathin semiconductor. The study was recently published in Nature Communications.Circularly Polarized Light Switching.

The device could function as a standard optical switch, where turning a control laser on or off switches the signal beam of the same polarization, or as a type of logic gate called Exclusive OR (XOR) switch, which would produce an output signal when one light input twists clockwise and the other is counterclockwise but not when both inputs are the same.

“Because a switch is the most elementary building block of any information processing unit, an all-optical switch is the first step towards all optical computing or building optical neural networks,” said Lingxiao Zhou, a physics doctoral student at U-M and lead author of the study.