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Caltech engineers create an optical gyroscope smaller than a grain of rice by Staff Writers Washington DC (SPX) Oct 26, 2018
Gyroscopes are devices that help vehicles, drones, and wearable and handheld electronic devices know their orientation in three-dimensional space. They are commonplace in just about every bit of technology we rely on every day. Originally, gyroscopes were sets of nested wheels, each spinning on a different axis. But open up a cell phone today, and you will find a microelectromechanical sensor (MEMS), the modern-day equivalent, which measures changes in the forces acting on two identical masses that are oscillating and moving in opposite directions. These MEMS gyroscopes are limited in their sensitivity, so optical gyroscopes have been developed to perform the same function but with no moving parts and a greater degree of accuracy using a phenomenon called the Sagnac effect.
What is the Sagnac Effect? Light travels at a constant speed, so rotating the device - and with it the pathway that the light travels - causes one of the two beams to arrive at the detector before the other. With a loop on each axis of orientation, this phase shift, known as the Sagnac effect, can be used to calculate orientation.
The Problem
The Invention
How it works In this case, "reciprocal" means that it affects both beams of the light inside the gyroscope in the same way. Since the Sagnac effect relies on detecting a difference between the two beams as they travel in opposite directions, it is considered nonreciprocal. Inside the gyroscope, light travels through miniaturized optical waveguides (small conduits that carry light, that perform the same function as wires do for electricity). Imperfections in the optical path that might affect the beams (for example, thermal fluctuations or light scattering) and any outside interference will affect both beams similarly. Hajimiri's team found a way to weed out this reciprocal noise while leaving signals from the Sagnac effect intact. Reciprocal sensitivity enhancement thus improves the signal-to-noise ratio in the system and enables the integration of the optical gyro onto a chip smaller than a grain of rice.
Research Report: "Nanophotonic optical gyroscope with reciprocal sensitivity enhancement"
Researchers discover directional and long-lived nanolight in a 2D material Washington DC (SPX) Oct 25, 2018 An international team led by researchers from Monash University (Melbourne, Australia), University of Oviedo (Asturias, Spain), CIC nanoGUNE (San Sebastian, Spain), and Soochow University (Suzhou, China) discover squeezed light ('nanolight') in the nanoscale that propagates only in specific directions along thin slabs of molybdenum trioxide - a natural anisotropic 2D material -. Besides its unique directional character, this nanolight lives for an exceptionally long time, and thus could find application ... read more
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