This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers have developed a chip-scale optical ring-laser gyroscope that can measure rotation as slow as 37 degrees per hour. This record sensitivity, approaching Earth's rotation rate of 15 degrees per hour, could eventually be useful for precision navigation and orientation systems, particularly where GPS is unavailable.
Gyroscopes measure how an object rotates, helping determine its orientation and movement. The chip-based gyroscopes found in smartphones and other everyday devices tend to have limited sensitivity, making them unsuitable for some demanding applications. This has driven scientists to develop chip-based versions of optical gyroscopes, which are sensitive enough for applications such as aircraft navigation.
"Our new gyroscope combines several advanced technologies to achieve a high level of sensitivity in a format that can be made with standard CMOS chip-processing methods and uses just milliwatts of optical power," said Daniel J. Blumenthal, who led the research team from the University of California, Santa Barbara. "A fully integrated optical gyroscope would not only be smaller than today's systems but also have no moving parts and thus be very resilient to vibrations and shocks." In the journal Optics Letters, the researchers describe the new device, which is based on a special type of low-noise laser made using a photonic integrated circuit made of silicon nitride waveguides.
Its sensitivity represents a nearly 2,000-fold improvement over the researchers' earlier silicon nitride Brillouin gyroscope, which measured rotation at 72,000 degrees per hour. "With more development, this type of optical gyroscope could eventually bring the high-precision sensing of optical gyroscopes to compact, chip-based devices," said Kerry Vahala, who led the research team from the California Institute of Technology. "That could offer a more mass-manufacturable and rugged device for application in cars, aircraft and spacecraft." To create the new gyroscope, the researchers combined a Brillouin laser gyroscope approach developed by Vahala's research team with a Brillouin laser-on-a-chip based on a silicon nitride platform developed by Blumenthal's group, working with the Air Force Research Laboratory.
Brillouin gyroscopes use light interacting with vibrations in the waveguide to create the low-noise laser signals needed for rotation sensing. The gyroscope approach developed by Vahala's research team is based on a ring-shaped microresonator that can confine light with very little loss and has a high quality (Q) factor, a measure of how well the ring holds light. This allows light to circulate many times, making it extremely sensitive to small changes caused by rotation.
In 2017, Vahala's team demonstrated the technology and later used a tiny silica optical resonator to detect the rotation of Earth. Blumenthal's group, with support from the Air Force Research Laboratory, developed photonic circuits made from silicon nitride, a material that can guide light with very little loss. The circuits are compatible with standard CMOS chip-manufacturing methods, offering a path to making the technology smaller and easier to manufacture.
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