# US 10,310,181 B2 · χ(2) modulators and related devices with barium titanate photonic crystal waveguides

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- Number: US 10,310,181 B2
- Document ID: US10310181B2
- Status: Granted
- Kind: B2
- Application number: 15/731,097
- Filed: 2017-04-17
- Published: 2017-10-19
- Granted: 2019-06-04
- Earliest claimed: 2016-04-15
- Assignees: Northwestern University
- Applicants: Northwestern University
- Inventors: Bruce W. Wessels; Zhifu Liu; Peter D. Girouard
- Web page: https://patentgrep.com/patent/US10310181B2

## CPC

- G02B 6/1225: {comprising photonic band-gap structures or photonic lattices}
- G02B 6/12007: {forming wavelength selective elements, e.g. multiplexer, demultiplexer}
- G02B 6/29352: {in a light guide}
- G02F 1/035: in an optical waveguide structure
- G02F 1/065: in an optical waveguide structure
- G02F 1/2257: {the optical waveguides being made of semiconducting material}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS

## Abstract

Barium titanate thin film waveguides and related modulator and devices with photonic crystal structures to promote wide bandwidths, low operating voltages and small footprint.

## Claims

### Claim 1

A modulator device comprising a photonic crystal waveguide, said waveguide comprising a substrate; a nano-dimensioned film component coupled to said substrate, said film component comprising BaTiO3; and a single nanodimensioned ridge component coupled to said film component, said ridge component having a refractive index less than the refractive index of said film component, said film and ridge components comprising an electro-optic medium and an array of spaced lines of holes therein, said array defining an absent line of holes in the direction of light propogation through said medium and two tapered regions at opposite ends of said defined absent line, each said tapered region comprising lines of holes positionally shifted a constant nanometric distance from an adjacent line of holes, said array providing said waveguide a photonic crystal structure.

### Claim 2 (depends on 1)

The device of claim 1 where said ridge component comprises Si3N4.

### Claim 3 (depends on 1)

The device of claim 1 comprising two opposed, substantially coplanar electrodes, each said electrode on an opposed side of said ridge component.

### Claim 4 (depends on 1)

The device of claim 1 comprising a hexagonal array of spaced lines of holes.

### Claim 5 (depends on 1)

The device of claim 1 comprising a length dimension up to about 2 millimeters.

### Claim 6 (depends on 1)

The device of claim 1 incorporated into a planar photonic integrated circuit.

### Claim 7

A modulator device comprising a photonic crystal waveguide, said waveguide comprising a substrate; a nano-dimensioned film component on said substrate, said film component comprising BaTiO3; a nanodimensioned Si3N4 ridge component on said film component; and two substantially coplanar electrodes, each said electrode on an opposite side of said ridge component, said film and ridge components comprising an electro-optic medium and an array of spaced lines of holes therein, said array defining an absent line of holes in the direction of light propogation through said medium and two tapered regions at opposite ends of said defined absent line, each said tapered region comprising lines of holes positionally shifted a constant nanometric distance from an adjacent line of holes, said array providing said waveguide a photonic crystal structure.

### Claim 8 (depends on 7)

The device of claim 7 comprising a hexagonal array of spaced lines of holes.

### Claim 9 (depends on 7)

The device of claim 7 comprising a length dimension up to about 2 millimeters.

### Claim 10 (depends on 7)

The device of claim 7 incorporated into a planar photonic integrated circuit.

### Claim 11 (depends on 10)

The device of claim 10 comprising a coherent optical transmitter.

### Claim 12 (depends on 7)

The device of claim 7 capable of modulating light waves of wavelength of about 0.4 to about 5 microns.

### Claim 13 (depends on 7)

The device of claim 7 capable of modulating TE and TM light modes suitable for optical coherent transmission systems.