Tiny optical gyroscope could find a home in phones and drones

The tiny device, which is smaller than a grain of rice, determines its position in three-dimensional space using what’s known as the Sagnac Effect. Based on the principles of general relativity, the Sagnac Effect occurs when a beam of light is split and the two resulting beams travel in opposite directions in a circle, arriving at the same light detector. Despite the fact that the speed of light is constant, rotating the plane in which these beams move causes one beam to arrive earlier than the other. When these loops are placed on each axis of orientation, the Sagnac Effect can be used to determine spatial position.

As optical gyroscopes are built smaller and smaller, so too is the signal that captures the Sagnac effect, which makes it more and more difficult for the device to detect movement. Up to now, this has prevented the miniaturisation of optical gyroscopes, with the smallest high-performance devices bigger than golf balls.