# How Chip-Scale Optical Gyroscopes Navigate Without GPS An episode of [The Hardware Podcast with Fexingo: Chips, Devices, and Electronics Engineering Conversations](https://invisiblenetwork.ai/podcast/1896799982), 27 Jul 2026, 6:38. Audio: https://audio.fexingo.com/business/the-hardware-podcast/episode-0135.mp3 In this episode of The Hardware Podcast, hosts Lucas and Luna explore the cutting-edge world of chip-scale optical gyroscopes—tiny sensors that can detect rotation with precision rivaling bulky fiber-optic gyros, all etched onto a silicon chip. They discuss the underlying physics of the Sagnac effect, how researchers at the University of Michigan and Caltech have pushed bias stability below 0.1 degrees per hour, and why these gyros are critical for autonomous vehicles, drones, and defense systems operating in GPS-denied environments. Lucas and Luna break down the manufacturing challenges, from ultra-low-loss waveguides to thermal isolation, and look ahead to commercial integration. The episode also touches on how precision engineering in chips mirrors the independence of listener-supported podcasting. #ChipScaleGyroscope #OpticalGyroscope #Navigation #GPSDenied #Photonics #SiliconPhotonics #MEMS #SensorTechnology #AutonomousDrones #PrecisionNavigation #UniversityOfMichigan #Caltech #EngineeringInnovation #Semiconductor #HardwareEngineering #Technology #FexingoBusiness #BusinessPodcast Keep every episode free: buymeacoffee.com/fexingo ## Transcript Lucas: Luna, imagine you're flying a drone through a tunnel where GPS doesn't reach. How does it know which way is up? Luna: I'd rely on accelerometers and magnetometers—standard MEMS sensors. But they drift, right? Especially in a tunnel with magnetic interference. Lucas: Exactly. That's where chip-scale optical gyroscopes come in. They use the Sagnac effect—basically, two beams of light travel clockwise and counterclockwise around a tiny ring on a chip. When the chip rotates, the beams shift relative to each other, and that shift measures rotation rate with incredible precision. Luna: So instead of a spinning mass or a vibrating tuning fork, it's light doing the work. How small are these rings? Lucas: We're talking micro-ring resonators with diameters smaller than a millimeter. The whole gyro can fit on a chip the size of a dime. And the bias stability—the drift over time—has been pushed below 0.1 degrees per hour. That's competitive with tactical-grade fiber-optic gyros that are the size of a soda can. Luna: 0.1 degrees per hour—that's impressive. How do they achieve that without the long fiber coils? Lucas: It comes down to the waveguide quality. Researchers at the University of Michigan recently demonstrated a chip-scale gyro using silicon nitride waveguides with propagation losses below 0.1 decibels per centimeter. They also use a technique called 'reciprocal sensitivity enhancement'—basically folding the optical path multiple times inside the resonator to increase the effective length without making the chip bigger. Luna: So it's like a miniature version of a fiber gyro, but with photonic integrated circuits. What about noise sources? Lucas: Thermal noise is a big one. Temperature fluctuations change the refractive index of the waveguide, which looks like rotation. So you need careful thermal isolation and sometimes active temperature control. Caltech has a design that uses a dual-ring configuration to cancel common-mode thermal drift. Luna: Makes sense. So where do these gyros actually get used? I'm guessing not in your smartphone accelerometer. Lucas: Not yet—they're still mostly in R&D. But the big push is for autonomous vehicles and drones that need to navigate when GPS is jammed or unavailable. Think underground mining robots, delivery drones in urban canyons, or military surveillance craft. Even some satellites use chip-scale gyros for attitude control when they lose lock with ground stations. Luna: What about commercial production? Can we buy these off the shelf? Lucas: Not quite. Companies like Honeywell and KVH are working on it, but the yields are still low. The main challenge is coupling light in and out of the chip efficiently—that fiber to chip alignment adds cost. But there's a move toward heterogeneous integration where the laser and detector are built directly on the same chip. Luna: So it's a classic semiconductor scaling problem. Once the process matures, costs should drop. Lucas: Exactly. And when that happens, we might see these gyros in everything from autonomous lawnmowers to VR headsets. The precision is there—it's just about manufacturing at scale. Luna: You know, this reminds me of how early MEMS gyros took a decade to go from lab to mass market. Optical gyroscopes might follow a similar curve. Lucas: I think you're right. And speaking of independence—the same drive for precision and self-reliance that makes optical gyros valuable is something we appreciate here on the show. We keep The Hardware Podcast ad-free and listener-supported because we want that same kind of independence. Luna: Yeah, it's a small gesture, but if today's episode gave you a useful insight or made you think differently about navigation, you can toss some support our way. It honestly helps us keep digging into topics like this. Lucas: If you're interested, you can find us at buy me a coffee dot com slash fexingo. No pressure—just a way for the people who care to help keep the show rolling. Luna: Alright, back to the gyro. So what's the next big milestone you're watching? Lucas: I'm looking at the integration with other sensors—creating a full inertial measurement unit on a chip. Imagine a single photonic chip that measures rotation, acceleration, and magnetic field. That would be a game-changer for size, weight, and power in drones. Luna: A photonic IMU. That would combine optical gyros with optical accelerometers. Are those on the horizon? Lucas: Yes—there's work at MIT on chip-scale optical accelerometers using similar ring resonator principles. But instead of measuring phase shift from rotation, they measure shift from acceleration-induced strain. Combined, you'd have a complete navigation system smaller than a fingernail. Luna: That's the kind of integration that could make gps denied navigation truly reliable. I'm thinking about search and rescue drones flying into collapsed buildings. Lucas: Exactly. Or autonomous underwater vehicles mapping the ocean floor. The potential is huge. Luna: One more question—how do these chip-scale optical gyros compare to the best MEMS gyros in terms of performance right now? Lucas: The best tactical-grade MEMS gyros achieve bias stability around 1 degree per hour. Optical chip-scale gyros are already an order of magnitude better—0.1 degrees per hour. And theoretically, with lower loss waveguides, they could reach 0.01 degrees per hour, which is navigation-grade. Luna: So the gap is closing fast. And it's all about that light whispering around a tiny ring. Lucas: Exactly. It's called the whispering-gallery mode—the light stays confined by total internal reflection, circumnavigating the ring thousands of times. Every lap increases the sensitivity. It's elegant physics that's finally becoming practical. Luna: Well, I'll never look at a drone the same way again. Thanks for diving into this. Lucas: Glad you found it interesting. And if you want to explore more, check out some of the open-access papers from the Optica journals—they paint a clear picture of where this technology is heading. Shows are listed from Apple Podcasts' charts and directory, and Podcast Index where it is used. Every show and episode belongs to its publisher and plays from the publisher's own feed; this site hosts none of them.