# US 11,442,226 B2 · Integrated photonics optical gyroscopes with improved sensitivity utilizing high density silicon nitride waveguides

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- Number: US 11,442,226 B2
- Document ID: US11442226B2
- Status: Granted
- Kind: B2
- Application number: 17/364,279
- Filed: 2021-06-30
- Published: 2022-01-06
- Granted: 2022-09-13
- Earliest claimed: 2020-07-01
- Assignees: Anello Photonics, Inc.
- Applicants: Anello Photonics, Inc.
- Inventors: Avi Feshali; Mario Paniccia; Warren Bruce Jin
- Web page: https://patentgrep.com/patent/US11442226B2

## CPC

- G02B 6/125: Bends, branchings or intersections
- G01C 19/72: with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers
- G01C 19/722: {of the mechanical construction}
- G02B 6/1225: {comprising photonic band-gap structures or photonic lattices}
- G02B 2006/12061: {Silicon}
- G02B 2006/12107: {Grating}
- G02B 2006/12138: {Sensor}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G01C: MEASURING DISTANCES, LEVELS OR BEARINGS; SURVEYING; NAVIGATION; GYROSCOPIC INSTRUMENTS; PHOTOGRAMMETRY OR VIDEOGRAMMETRY (measuring liquid level G01F; radio navigation, determining distance or velocity by use of propagation effects, e.g. Doppler effects, propagation time, of radio waves, analogous arrangements using other waves G01S)

## 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.

## Claims

### Claim 1

An integrated photonics chip comprising:
a waveguide coil comprising a plurality of waveguide turns looping around a central area enclosed by the waveguide coil, each waveguide turn being parallel to adjacent waveguide turns, wherein each waveguide turn comprises a waveguide core sandwiched between an upper cladding and a lower cladding; and
a structural modification introduced on either side of each waveguide turn to reduce crosstalk between the adjacent waveguide turns, thereby increasing a spatial density of waveguide turns that can be fabricated within a predetermined area of the integrated photonics chip, wherein the structural modification comprises a gap.

### Claim 2 (depends on 1)

The integrated photonics chip of claim 1, wherein the predetermined area depends on an exposure field of a reticle used to fabricate the waveguide coil with the plurality of turns.

### Claim 3 (depends on 1)

The integrated photonics chip of claim 1, wherein the waveguide coil is used as a rotational sensing element of an optical gyroscope.

### Claim 4 (depends on 3)

The integrated photonics chip of claim 3, wherein increasing spatial density of waveguide turns increases the central area enclosed within the waveguide coil, as well as increases a number of waveguide turns enclosing the central area, thereby increasing sensitivity of the rotational sensing element.

### Claim 5 (depends on 1)

The integrated photonics chip of claim 1, wherein each waveguide turn comprises a waveguide core sandwiched between an upper cladding and a lower cladding.

### Claim 6 (depends on 1)

The integrated photonics chip of claim 1, wherein the waveguide core comprises silicon nitride and the upper cladding and lower cladding comprise oxide.

### Claim 7 (depends on 1)

The integrated photonics chip of claim 1, wherein the gap is filled with a fluid.

### Claim 8 (depends on 1)

The integrated photonics chip of claim 1, wherein the gap is filled with air.

### Claim 9 (depends on 7)

The integrated photonics chip of claim 7, wherein the fluid comprises a non-reactive liquid or gas creating a fluid barrier between two adjacent waveguide turns.

### Claim 10 (depends on 1)

The integrated photonics chip of claim 1, wherein the gap is in the form of a high-aspect-ratio rectangular slit or trench with a longitudinal dimension of the gap being substantially higher than a lateral dimension of the gap.

### Claim 11 (depends on 10)

The integrated photonics chip of claim 10, wherein the longitudinal dimension of the gap extends through the upper cladding past the waveguide core deep into the lower cladding, wherein the longitudinal dimension of the gap is substantially above and below a longitudinal dimension of the waveguide core adjacent to it.

### Claim 12 (depends on 1)

The integrated photonic chip of claim 1, wherein a pitch between adjacent waveguide turns is in the range of 10 micron.