TECH

The world's smallest optical gyro fits into a large rice paddy

Optical Gyroscope

This is the smallest version ever made of an optical gyroscope, an inertial positioning device that replaces moving mechanical parts with light beams.Within a conventional optical gyroscope, a coiled optical fiber carries laser pulses, some rotating clockwise and some counterclockwise.The device measures the rate of rotation by detecting small changes at the time of the arrival of each of the pulses to a sensor.It is difficult to miniaturize these optical gyroscopes because when their size is decreased, the signal from the sensors weakens and begins to get mixed up in the noise created by the diffusion of light into the optical fiber.To counteract this effect, Parham Khial and his colleagues at the California Institute of Technology designed a low-noise photonic gyroscope.Khial carved out light-guiding channels on a 2-millimeter square-shaped silicon chip to make light travel in each direction by rotating around a separate circle so scattered light does not confuse the sensors. The unit also periodically reverses the direction of the light, which helps cancel out much of the noise.Miniaturization will enable devices with far greater precision than current mechanical devices.

Bibliography:Nanophotonic optical gyroscope with reciprocal sensitivity enhancement
Parham P. Khial, Alexander D. White, Ali Hajimiri
Nature Photonics