# US 9,519,163 B2 · Tunable silicon grating couplers

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- Number: US 9,519,163 B2
- Document ID: US9519163B2
- Status: Granted
- Kind: B2
- Application number: 14/034,950
- Filed: 2013-09-24
- Published: 2015-03-26
- Granted: 2016-12-13
- Earliest claimed: 2013-09-24
- Assignees: Oracle International Corporation
- Applicants: Oracle International Corporation
- Inventors: Xuezhe Zheng; Jin Yao; Guoliang Li; Ying L. Luo; John E. Cunningham; Ashok V. Krishnamoorthy
- Web page: https://patentgrep.com/patent/US9519163B2

## CPC

- G02F 1/025: in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence)
- G02B 6/124: Geodesic lenses or integrated gratings
- G02B 6/24: Coupling light guides
- G02B 6/29395: {configurable, e.g. tunable or reconfigurable (switching G02B6/35)}
- G02F 1/0154: {using electro-optic effects, e.g. linear electro optic [LEO], Pockels, quadratic electro optical [QEO] or Kerr effect}
- G02F 2201/302: grating coupler
- 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
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A photonic integrated circuit (PIC) is described. This PIC includes a grating coupler for surface-normal coupling that has an alternating pattern of grating teeth and grating trenches, where the grating trenches are filled with an electro-optical material. By applying an electric potential to the grating teeth, the index of refraction of the electro-optical material can be modified.

## Claims

### Claim 1

An integrated circuit, comprising:
a substrate;
a buried-oxide layer disposed on the substrate;
a semiconductor layer, disposed on the buried-oxide layer, having a top surface; and
a grating coupler, disposed in the semiconductor layer, having an alternating pattern of grating trenches and grating teeth adjacent to the grating trenches, wherein the grating coupler is a portion of the semiconductor layer, and wherein the grating trenches extend all the way through the semiconductor layer from the top surface to the buried-oxide layer;
wherein the grating trenches are filled with an electro-optical material; and
wherein the grating teeth are configured as electrodes to apply an electric potential across the electro-optical material to modify an index of refraction of the electro-optical material.

### Claim 2 (depends on 1)

The integrated circuit of claim 1, wherein the modification to the index of refraction changes one of: an operating wavelength of the grating coupler, a position alignment criterion of the grating coupler, and an angular alignment criterion of the grating coupler.

### Claim 3 (depends on 1)

The integrated circuit of claim 1, wherein the semiconductor layer under the grating teeth includes one of: an n-type dopant and a p-type dopant.

### Claim 4 (depends on 1)

The integrated circuit of claim 1, wherein the semiconductor layer under the grating teeth includes a p-type dopant and an n-type dopant; and
wherein the p-type dopant is included under alternating grating teeth and the n-type dopant is included under grating teeth interposed between the alternating grating teeth.

### Claim 5 (depends on 4)

The integrated circuit of claim 4, wherein the electric potential reverse biases pn-junctions in the semiconductor layer to deplete carriers.

### Claim 6 (depends on 1)

The integrated circuit of claim 1, wherein the grating trenches are etched from the top surface to the buried-oxide layer.

### Claim 7 (depends on 1)

The integrated circuit of claim 1, wherein the substrate, the buried-oxide layer and the semiconductor layer comprise a silicon-on-insulator technology.

### Claim 8 (depends on 1)

The integrated circuit of claim 1, wherein the semiconductor layer includes silicon.

### Claim 9

A system, comprising an integrated circuit, wherein the integrated circuit includes:
a substrate;
a buried-oxide layer disposed on the substrate;
a semiconductor layer, disposed on the buried-oxide layer, having a top surface; and
a grating coupler, disposed in the semiconductor layer, having an alternating pattern of grating trenches and grating teeth adjacent to the grating trenches, wherein the grating coupler is a portion of the semiconductor layer, and wherein the grating trenches extend all the way through the semiconductor layer from the top surface to the buried-oxide layer;
wherein the grating trenches are filled with an electro-optical material; and
wherein the grating teeth are configured as electrodes to apply an electric potential across the electro-optical material to modify an index of refraction of the electro-optical material.

### Claim 10 (depends on 9)

The system of claim 9, wherein the modification to the index of refraction changes one of: an operating wavelength of the grating coupler, a position alignment criterion of the grating coupler, and an angular alignment criterion of the grating coupler.

### Claim 11 (depends on 9)

The system of claim 9, wherein the semiconductor layer under the grating teeth includes one of: an n-type dopant and a p-type dopant.

### Claim 12 (depends on 9)

The system of claim 9, wherein the semiconductor layer under the grating teeth includes a p-type dopant and an n-type dopant; and
wherein the p-type dopant is included under alternating grating teeth and the n-type dopant is included under grating teeth interposed between the alternating grating teeth.

### Claim 13 (depends on 12)

The system of claim 12, wherein the electric potential reverse biases pn-junctions in the semiconductor layer to deplete carriers.

### Claim 14 (depends on 9)

The system of claim 9, wherein the grating trenches are etched from the top surface to the buried-oxide layer.

### Claim 15 (depends on 9)

The system of claim 9, wherein the substrate, the buried-oxide layer and the semiconductor layer comprise a silicon-on-insulator technology.

### Claim 16 (depends on 9)

The system of claim 9, wherein the semiconductor layer includes silicon.