Scientists are developing the world's smallest optical gyroscope – a device for helping vehicles and drones in 3D space

Scientists have developed the world's smallest optical gyroscope – a device that allows vehicles, drones and portable and portable electronic devices to know their orientation in a three-dimensional space.

The new gyro, described in Nature Photonics, is 500 times smaller than the state-of-the-art device.

Originally, the gyroscopes were nested wheel sets, each rotating on a different axis, researchers at the California Institute of Technology in the United States said.

However, today's mobile phones have a microelectromechanical sensor (MEMS), the modern equivalent, which measures changes in forces acting on two identical masses that oscillate and move in opposite directions.

The sensitivity of these MEMS gyroscopes being limited, optical gyroscopes have been developed to fulfill the same function but without moving parts and with a higher degree of precision thanks to a phenomenon called Sagnac effect.

The Sagnac effect, named after the French physicist Georges Sagnac, is an optical phenomenon rooted in Einstein's theory of general relativity.

The researchers pointed out that the smallest high performance optical gyroscopes available today are bigger than a golf ball and are not suitable for many portable applications.

As optical gyroscopes are built smaller and smaller, the signal capturing the Sagnac effect is also, making it increasingly difficult to detect motion by the gyroscope, they said.

Until now, this prevented the miniaturization of optical gyroscopes.

Caltech engineers led by Professor Ali Hajimiri have developed a new optical gyroscope 500 times smaller than the state-of-the-art device, but they can detect phase shifts that are 30 times smaller than these systems.

The new gyroscope improves performance by using a new technique called "improving reciprocal sensitivity".

In this case, "reciprocal" means that it affects the two beams of light inside the gyroscope in the same way.

Since the Sagnac effect relies on the detection of a difference between the two beams when they move in opposite directions, it is considered nonreciprocal.

Inside the gyroscope, light travels through miniaturized optical waveguides (small light carrying ducts, which perform the same function as wires for electricity).

Imperfections in the optical path that may affect the beams (for example, thermal fluctuations or light scattering) and any external interference will affect both beams in the same way.

Hajimiri's team found a way to eliminate this mutual noise while leaving the signals of the Sagnac effect intact.

The improvement of the reciprocal sensitivity thus improves the signal-to-noise ratio in the system and allows the integration of the optical gyroscope on a chip smaller than a grain of rice.