Researchers at the University of California, Santa Barbara, and Caltech have developed a chip-scale optical gyroscope that can detect rotation as slow as 37 degrees per hour, nearly 2,000 times slower than an earlier silicon nitride design.

The result brings the sensor closer to measuring Earth’s rotation rate of 15 degrees per hour. It could eventually help develop compact navigation systems for aircraft, vehicles and spacecraft operating where GPS signals are unavailable.

Unlike conventional gyroscopes that rely on mechanical movement, the new device uses light traveling through a ring-shaped optical circuit to detect rotation. The researchers say the approach could offer high-precision sensing in a smaller, more durable package.

The experimental gyroscope uses silicon nitride, a material compatible with standard CMOS chip-manufacturing processes. Its sensing circuit measures about 24 millimeters across, while the packaged device is only a few centimeters wide.

The researchers combined two previously developed technologies: a Brillouin laser gyroscope from Caltech and a low-noise laser-on-a-chip platform developed at UC Santa Barbara with support from the Air Force Research Laboratory.

Inside the device, two semiconductor lasers send light in opposite directions around a ring-shaped circuit. Interactions between the light and vibrations in the material generate two stable laser signals.

When the device rotates, the frequencies of these signals shift slightly relative to each other. Measuring that difference allows the gyroscope to determine the rotation rate.

The ring’s ability to retain light is central to its sensitivity. Its quality factor, a measure of how efficiently an optical resonator stores light, exceeds 163 million.

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