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KVH has developed a working prototype of a new, patent- pending type of autonomous vehicle fibre optic gyroscope (FOG) that uses a photonic IC to give improved inertial navigation performance and reduced costs (writes Rory Jackson). “We were able to integrate the key components of our FOG monolithically using photonic processes,” said Jan Khan, principal optical design engineer at KVH. “It is lighter, smaller and uses less power than a conventional FOG for autonomous systems, as a result of transferring from a silicon IC to a photonic one. The optical circuit is reduced in size by an order of magnitude.” The use of the photonic chip will enable more accurate navigation and positioning than FOGs – and by extension, MEMS IMUs – could previously provide. For example, the angular random walk (or ‘noise’) of the prototype photonic gyro has been calculated at <0.0097°/ √ hour, roughly half of that in the company’s typical FOG systems. In addition, bias instability (or ‘drift’) of the prototype is 0.02°/hour, around one-fifth of general FOG drift. “The increases in accuracy are directly linked to the photonic portion of the gyro,” Khan added. “We can control the optical performance figures much more tightly through the lithography than we could using conventional FOG technology such as fibre couplers.” “We also have additional scalability of the technology that comes from the reduction in fabrication time, as fabricating a photonic integrated circuit means more precision and repeatability, with less manual assembly of individual components,” he said. FOG uses a photonic IC Navigation Our fibre optic gyroscope is lighter, smaller and uses less power than a conventional FOG for autonomous systems, as a result of using a photonic IC