Abstract: The present disclosure relates to integration of integrated photonics-based optical gyroscopes and fiber-based optical gyroscopes into portable apparatuses that may include compass features. Novel small-footprint modularized fully integrated photonics optical gyroscopes are used for non-critical axes. However, for at least one critical axis, a fiber-optic gyroscope can be used to provide bias stability below 0.1°/Hr, which is directly correlated to predicting positional accuracy in the centimeter range. The positional accuracy results from the compassing ability of the gyroscope (referred to as gyrocompass) to calculate direction of heading using the earth's rotation.

Abstract: An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises (SiN) waveguide-based optical components that constitute a front-end chip to launch light into and receive light from the rotation sensing element, that can be a fiber spool. The SiN waveguide-based components can be distributed between multiple layers that are stacked together to have a multi-layer configuration vertically and evanescently coupled with each other. External elements (e.g., laser, detectors, phase shifter) may be made of different material platform than SiN and can be hybridly integrated or otherwise coupled to the SiN waveguide platform. The phase shifters can be made of electro-optic material, or piezo-electric material or can be thermal phase shifters.

Abstract: Aspects of the present disclosure are directed to structural modifications introduced in a waveguide structure in order to more tightly pack adjacent waveguide turns in an optical gyroscope fabricated on a planar silicon platform as a photonic integrated circuit. Increasing number of turns of the gyroscope coil increases total waveguide length as well as enclosed area of the gyroscope loop, which translates to increased sensitivity to rotational measurement.

Abstract: Aspects of the present disclosure are directed to fabrication of large-footprint chips having integrated photonic components comprising low-loss optical waveguides. The large footprint chips require the use of multiple reticles during fabrication. Stitching adjacent reticle fields seamlessly is accomplished by overlaying into adjacent reticle fields, tapering waveguide ends, and using strategically placed alignment marks in the die.

Abstract: The present disclosure relates to integrated photonics-based optical gyroscopes with silicon nitride (SiN) waveguide-based microresonators. SiN microresonators are fabricated either on a fused silica platform or on a silicon substrate with oxide cladding. A narrow linewidth high-Q laser is hybridly integrated on a silicon photonics platform. The laser is tuned with a first SiN microresonator, and the rotational sensing component of the gyroscope comprises another SiN microresonator. The silicon photonics front-end chip has components for a balanced detection scheme to cancel noise in the optical signal coming back from the rotational sensing component.

Abstract: Aspects of the present disclosure are directed to configurations of compact ultra-low loss integrated photonics-based waveguides for optical gyroscope applications, and the methods of fabricating those waveguides for ease of large scale manufacturing. Four main process flows are described: (1) process flow based on a repeated sequence of oxide deposition and anneal; (2) chemical-mechanical polishing (CMP)-based process flow followed by wafer bonding; (3) Damascene process flow followed by oxide deposition and anneal, or wafer bonding; and (4) CMP-based process flows followed by oxide deposition. Any combination of these process flows may be adopted to meet the end goal of fabricating optical gyroscope waveguides in one or more layers on a silicon substrate using standard silicon fabrication technologies.

Abstract: Novel small-footprint integrated photonics optical gyroscopes disclosed herein can provide ARW in the range of 0.05°/?Hr or below (e.g. as low as 0.02°/?Hr), which makes them comparable to fiber optic gyroscopes (FOGs) in terms of performance, at a much lower cost. The low bias stability value in the integrated photonics optical gyroscope corresponds to a low bias estimation error (in the range of 1.5°/Hr or even lower) that is crucial for safety-critical applications, such as calculating heading for autonomous vehicles, drones, aircrafts etc. The integrated photonics optical gyroscopes may be co-packaged with mechanical gyroscopes into a hybrid inertial measurement unit (IMU) to provide high-precision angular measurement for one or more axes.

Abstract: Disclosed herein are configurations and methods to produce very low loss waveguide structures, which can be single-layer or multi-layer. These waveguide structures can be used as a sensing component of a small-footprint integrated optical gyroscope. By using pure fused silica substrates as both top and bottom cladding around a SiN waveguide core, the propagation loss can be well below 0.1 db/meter. Low-loss waveguide-based gyro coils may be patterned in the shape of a spiral (circular or rectangular or any other shape), that may be distributed among one or more of vertical planes to increase the length of the optical path while avoiding the increased loss caused by intersecting waveguides in the state-of-the-art designs. Low-loss adiabatic tapers may be used for a coil formed in a single layer where an output waveguide crosses the turns of the spiraling coil.

Abstract: Aspects of the present disclosure are directed to structural modifications introduced in a waveguide structure in order to more tightly pack adjacent waveguide turns in an optical gyroscope fabricated on a planar silicon platform as a photonic integrated circuit. Increasing number of turns of the gyroscope coil increases total waveguide length as well as enclosed area of the gyroscope loop, which translates to increased sensitivity to rotational measurement.

Abstract: An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises (SiN) waveguide-based optical components that constitute a front-end chip to launch light into and receive light from the rotation sensing element, that can be a fiber spool. The SiN waveguide-based components can be distributed between multiple layers that are stacked together to have a multi-layer configuration vertically and evanescently coupled with each other. External elements (e.g., laser, detectors, phase shifter) may be made of different material platform than SiN and can be hybridly integrated or otherwise coupled to the SiN waveguide platform. The phase shifters can be made of electro-optic material, or piezo-electric material or can be thermal phase shifters.

Abstract: Novel small-footprint integrated photonics optical gyroscopes disclosed herein can provide ARW in the range of 0.05°/?Hr or below (e.g. as low as 0.02°/?Hr), which makes them comparable to fiber optic gyroscopes (FOGs) in terms of performance, at a much lower cost. The low bias stability value in the integrated photonics optical gyroscope corresponds to a low bias estimation error (in the range of 1.5°/Hr or even lower) that is crucial for safety-critical applications, such as calculating heading for autonomous vehicles, drones, aircrafts etc. The integrated photonics optical gyroscopes may be co-packaged with mechanical gyroscopes into a hybrid inertial measurement unit (IMU) to provide high-precision angular measurement for one or more axes.

Abstract: Disclosed herein are configurations and methods to produce very low loss waveguide structures, which can be single-layer or multi-layer. These waveguide structures can be used as a sensing component of a small-footprint integrated optical gyroscope. By using pure fused silica substrates as both top and bottom cladding around a SiN waveguide core, the propagation loss can be well below 0.1 db/meter. Low-loss waveguide-based gyro coils may be patterned in the shape of a spiral (circular or rectangular or any other shape), that may be distributed among one or more of vertical planes to increase the length of the optical path while avoiding the increased loss caused by intersecting waveguides in the state-of-the-art designs. Low-loss adiabatic tapers may be used for a coil formed in a single layer where an output waveguide crosses the turns of the spiraling coil.

Abstract: The present disclosure relates to integrated photonics-based optical gyroscopes with silicon nitride (SiN) waveguide-based microresonators. SiN microresonators are fabricated either on a fused silica platform or on a silicon substrate with oxide cladding. A narrow linewidth high-Q laser is hybridly integrated on a silicon photonics platform. The laser is tuned with a first SiN microresonator, and the rotational sensing component of the gyroscope comprises another SiN microresonator. The silicon photonics front-end chip has components for a balanced detection scheme to cancel noise in the optical signal coming back from the rotational sensing component.

Abstract: Aspects of the present disclosure are directed to configurations of compact ultra-low loss integrated photonics-based waveguides for optical gyroscope applications, and the methods of fabricating those waveguides for ease of large scale manufacturing. Four main process flows are described: (1) process flow based on a repeated sequence of oxide deposition and anneal; (2) chemical-mechanical polishing (CMP)-based process flow followed by wafer bonding; (3) Damascene process flow followed by oxide deposition and anneal, or wafer bonding; and (4) CMP-based process flows followed by oxide deposition. Any combination of these process flows may be adopted to meet the end goal of fabricating optical gyroscope waveguides in one or more layers on a silicon substrate using standard silicon fabrication technologies.

Abstract: The present disclosure relates to system-level integration of lasers, electronics, integrated photonics-based optical components and a rotation sensing element, which can be a fiber coil or a sensing coil/micro-resonator ring on a sensing chip. Novel waveguide design on the integrated photonics chip, acting as a front-end chip, ensures precise detection of phase change in the fiber coil or the sensing chip, where the sending chip is coupled to the front end chip. Electrical and/or thermal phase modulators are integrated with the integrated photonics chip. Additionally, implant regions are introduced around the waveguides and other optical components to block unwanted/stray light into the waveguides and optical signal leaking out of the waveguide.

Abstract: An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first silicon nitride (SiN) waveguide layer that constitute a rotation sensing element; and, a second SiN waveguide layer with additional silicon nitride (SiN) waveguide-based optical components that constitute a front-end chip to launch light into and receive light from the rotation sensing element. The two SiN waveguide layers can be stacked together to have a multi-layer configuration vertically coupled with each other. External elements (e.g., laser, detectors, phase shifter) may be made of different material platform than SiN and can be hybridly integrated to the SiN waveguide platform. The phase shifters can be made of aluminum nitride (AlN) or strontium bismuth titanate (SBT).

Abstract: Aspects of the present disclosure are directed to fabrication of large-footprint chips having integrated photonic components comprising low-loss optical waveguides. The large footprint chips require the use of multiple reticles during fabrication. Stitching adjacent reticle fields seamlessly is accomplished by overlaying into adjacent reticle fields, tapering waveguide ends, and using strategically placed alignment marks in the die.

Abstract: Aspects of the present disclosure are directed to structural modifications introduced in a waveguide structure in order to more tightly pack adjacent waveguide turns in an optical gyroscope fabricated on a planar silicon platform as a photonic integrated circuit. Increasing number of turns of the gyroscope coil increases total waveguide length as well as enclosed area of the gyroscope loop, which translates to increased sensitivity to rotational measurement.

Abstract: An integrated photonics optical gyroscope fabricated on a silicon nitride (SiN) waveguide platform comprises a first straight waveguide to receive incoming light and to output outgoing light to be coupled to a photodetector to provide an optical signal for rotational sensing. The gyroscope comprises a first microresonator ring proximate to the first straight waveguide. Light evanescently couples from the first straight waveguide to the first microresonator ring and experiences propagation loss while circulating as a guided beam within the first microresonator ring. The guided beam evanescently couples back from the first microresonator ring to the first straight waveguide to provide the optical signal for rotational sensing after optical gain is imparted to guided beam to counter the propagation loss. In a coupled-ring configurations, the first microresonator ring acts as a loss ring, and optical gain is imparted to a second microresonator ring which acts as a gain ring.

Abstract: Aspects of the present disclosure are directed to configurations of compact ultra-low loss integrated photonics-based waveguides for optical gyroscope applications, and the methods of fabricating those waveguides for ease of large scale manufacturing. Four main process flows are described: (1) process flow based on a repeated sequence of oxide deposition and anneal; (2) chemical-mechanical polishing (CMP)-based process flow followed by wafer bonding; (3) Damascene process flow followed by oxide deposition and anneal, or wafer bonding; and (4) CMP-based process flows followed by oxide deposition. Any combination of these process flows may be adopted to meet the end goal of fabricating optical gyroscope waveguides in one or more layers on a silicon substrate using standard silicon fabrication technologies.