INTERFEROMETRIC INTEGRATED OPTICAL GYROSCOPES

An optical waveguide structure for an optical gyroscope, the structure including a substrate; at least a first silicon nitride waveguide loop and a second silicon nitride waveguide loop connected to the substrate, the first silicon nitride waveguide loop and the second silicon nitride waveguide being disposed at different vertical distances from the substrate; at least one vertical coupler optically coupling the first silicon nitride waveguide loop to the second silicon nitride waveguide; and a plurality of air cavities defined in material below the first and second silicon nitride waveguide loops, no air cavities being defined in regions immediately below a coupling region defined around the at least one vertical coupler.