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: 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: One or more phase modulators in an optical gyroscope operate on two counter-propagating beams to introduce a phase shift between the beams before the beams are interferometrically combined to generate a rotation signal. A signal generator generates first and second modulation frequencies to drive the phase modulators. The first modulation frequency in isolation biases the rotation signal at an operating point sensitive to rotation, and the second modulation frequency in isolation biases the rotation signal at an operating point insensitive to rotation. One or more control integrated circuits (ICs) isolate a first portion of the rotation signal associated with the first modulation frequency and a second portion of the rotation signal associated with the second modulation frequency. The control ICs determine a difference between the first and second portions of the rotation signal to remove one or more bias instabilities from the first portion of the rotation signal.

Abstract: One or more phase modulators in an optical gyroscope operate on two counter-propagating beams to introduce a phase shift between the beams before the beams are interferometrically combined to generate a rotation signal. A signal generator generates first and second modulation frequencies to drive the phase modulators. The first modulation frequency in isolation biases the rotation signal at an operating point sensitive to rotation, and the second modulation frequency in isolation biases the rotation signal at an operating point insensitive to rotation. One or more control integrated circuits (ICs) isolate a first portion of the rotation signal associated with the first modulation frequency and a second portion of the rotation signal associated with the second modulation frequency. The control ICs determine a difference between the first and second portions of the rotation signal to remove one or more bias instabilities from the first portion of the rotation signal.

Abstract: Aspects of the present disclosure are directed to introducing structural modifications in a waveguide-based optical structure in order to more tightly pack adjacent waveguide turns in the optical structure. The optical structure can be used as the rotational sensing element of an optical gyroscope fabricated on a planar silicon platform as a photonic integrated circuit. Increasing number of turns of a waveguide-based gyroscope coil increases total waveguide length as well as enclosed area of the gyroscope loop, which translates to increased sensitivity to rotational measurement. The structural modifications can be in the form of air-gaps or fluid-filled or metal-filled gaps, or various types of sub-wavelength structures (like gratings or photonic crystals).

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 front-end chip is fabricated on a waveguide platform made of electro-optic materials. The front-end chip launches light into and receive light from the rotation sensing element, that can be a fiber spool or a waveguide coil/microresonator ring. The waveguide coil/microresonator ring can be made of the same electro-optic material platform or a different material platform. External elements (e.g., laser, detectors, phase shifter) may be made of different material platform than the electro-optic material and can be hybridly integrated or otherwise coupled to the waveguide platform. Additional phase shifters can be made of piezo-electric material or can be thermal phase shifters.

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: 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.