Intel Corporation

Anello Photonics, Inc.

Corning Incorporated

R-stor Inc.

Checkpoint Technologies LLC

Versalume LLC

Mario J Paniccia

Ansheng Liu

Dmitri E Nikonov

Michael T Morse

Avi Feshali

Qing Tan

Remus Nicolaescu

Richard O Jones

Yi Ding

Mike Horton

Haisheng Rong

Valluri Ramana Rao

Olufemi I Dosunmu

Dean Samara-Rubio

Andrew Alduino

Sean M Koehl

Tim L Kitchen

William R Headley

Warren Bruce Jin

Ian A Young

Paul Winer

Giovanni Coglitore

Graham Trevor Reed

Evan R Green

Travis M Eiles

Roger Levinson

Chris Wagner

Guy S Anthony

Ying-hao Kuo

John E Bowers

Edward Allyn Burton

John Heck

Timothy J Maloney

Thomas P Thomas

Ling Liao

Alexander W Fang

Hyundai Park

Oded Cohen

Guoqing Xiao

Assia Barkai

Kirk Hayden

I-Wei Andy Hsieh

Chi D Chu

Rami Cohen

Shiomo Ovadia

Valluri R M Rao

Valluri Rm Rao

Kerry Keating

Wai Mun Yee

Karl J Ma

Nathan Abrams

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.

Ring waveguide based integrated photonics optical gyroscope with balanced detection scheme

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.

Structures for integrated silicon photonics optical gyroscopes

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.

Silicon nitride waveguide based integrated photonics front-end chip for optical gyroscope

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.

Portable optical gyroscope and compass unit

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.

Integrated photonics optical gyroscopes optimized for autonomous vehicles

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.

Mitigating bias instabilities in optical gyroscopes

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.

Integrated photonics optical gyroscopes with improved sensitivity utilizing high density silicon nitride waveguides

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.

Seamless stitching for multi-reticle fabrication of integrated photonics optical components

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.

Process flow for fabricating integrated photonics optical gyroscopes

Novel small-footprint integrated photonics optical gyroscopes disclosed herein can provide ARW in the range of 0.05&#xb0;/&#x221a;Hr or below (e.g. as low as 0.02&#xb0;/&#x221a;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&#xb0;/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.

Integrated photonics optical gyroscopes optimized for autonomous terrestrial and aerial vehicles

Structures for integrated silicon photonics optical gyroscopes with structural modifications at waveguide crossing

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).

Silicon nitride waveguide based integrated photonics optical gyroscope chip with novel materials for phase shifter

Growing community of inventors

Santa Clara, CA, United States of America

Mario J Paniccia