Background:

Since the introduction of the first ring laser gyroscope (RLG) and later the fiber optic gyroscope (FOG), optical gyroscopes have become a mainstay of the global aerospace and defense industry, being used in civilian and military air craft, rockets, and missiles for inertial navigation and varying other applications such as vehicle and antenna Stabilization. Both gyroscopes operate via the Sagnac effect by which light traveling around a closed path experiences in the presence of an inertial rotation an increased optical path length when co-propagating with the rotation and a decreased path length when counter-propagating relative to the rotation.

The phase shift can be measured as an interference pattern in the optical intensity when the two beams are combined in a FOG or as a frequency splitting of the lasing modes of the RLG. Despite their success, RLGs and FOGs are unsuitable for many portable device applications because of their relatively large size and weight.

Summary:

A microfabricated optical gyroscope that utilizes a linear array of micron scale optical ring resonators closely spaced to allow evanescent coupling of electromagnetic fields in adjacent resonators. Within each resonator, the optical Sagnac effect produces a phase difference between clockwise and counterclockwise propagating light that is proportional to the inertial rotation rate perpendicular to the plane of the resonator. The disclosure enhances the overall sensitivity to rotations by varying the strengths of the evanescent coupling between resonators and/or the circumferences of the resonators. The size and coupling strengths control the optical interference between resonators. By using periodically alternating coupling strengths and/or linearly chirped resonator circumferences, the gyroscope transmission has extremely narrow transmission resonances with slopes, corresponding to the responsivity to inertial rotations, that are large enough to yield shot noise limited sensitivities sufficient for inertial navigation in a device size less the 1 mm2 in size.

Benefits:

- Microfabricated photonic devices

Applications:

- Optical gyroscopes

Full Patent: Actively Controlled Coupling And Size Modulation Microring Resonator Array Optical Gyroscope