Integrated electro-absorption modulator

Patent metadata

Field	Value
Publication number	US-9411177-B2
Application number	US-201514742431-A
Country	US
Kind code	B2
Filing date	Jun 17, 2015
Priority date	Apr 14, 2014
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

An integrated optical device includes an electro-absorption modulator disposed on a top surface of an optical waveguide. The electro-absorption modulator includes germanium disposed in a cavity between an n-type doped silicon sidewall and a p-type doped silicon sidewall. By applying a voltage between the n-type doped silicon sidewall and the p-type doped silicon sidewall, an electric field can be generated in a plane of the optical waveguide, but perpendicular to a propagation direction of the optical signal. This electric field shifts a band gap of the germanium, thereby modulating the optical signal.

First claim

What is claimed is:

1. A method for modulating an optical signal, wherein the method comprises:
conveying the optical signal in an optical waveguide in a propagation direction; and
applying a voltage to an n-type doped silicon sidewall and a p-type doped silicon sidewall in an electro-absorption modulator disposed on top of the optical waveguide, wherein the voltage generates a lateral electric field in germanium between the n-type doped silicon sidewall and the p-type doped silicon sidewall; and
wherein the lateral electric field is parallel to a plane of the optical waveguide and is perpendicular to the propagation direction.

2. The method of claim 1 ,
wherein the optical waveguide includes a top surface that conveys an optical signal having a wavelength along a propagation direction; and
wherein is electro-absorption modulator is disposed on the top surface and includes:
the n-type doped silicon sidewall;
the p-type doped silicon sidewall;
the germanium disposed between the n-type doped silicon sidewall and the p-type doped silicon sidewall; and
electrical contacts electrically coupled to the n-type doped silicon sidewall and the p-type doped silicon sidewall, wherein the electrical contacts apply a voltage between the n-type doped silicon sidewall and the p-type doped silicon sidewall to generate an electric field along a lateral direction in the germanium, and
wherein the lateral direction is parallel to a plane of the optical waveguide and is perpendicular to the propagation direction.

3. The method of claim 1 , wherein the n-type doped silicon sidewall and the p-type doped silicon sidewall are included in a ring of silicon;
wherein the ring of silicon includes a cavity defined by an edge; and
wherein the germanium is disposed in the cavity.

4. The method of claim 1 , wherein an optical device comprising the optical waveguide and the optical modulator further includes inverse optical tapers defined in the germanium; and
wherein the inverse optical tapers are configured to control a spatial extent of an optical mode in the germanium.

5. The method of claim 4 , wherein the inverse optical tapers include doped regions in the germanium.

6. The method of claim 1 , wherein the germanium has a thickness between 300 and 600 nm.

7. The method of claim 1 , wherein there exist mirrors on either side of the electro-absorption modulator.

8. The method of claim 7 , wherein the mirrors include distributed Bragg gratings.

Assignees

• Oracle Int Corp

Inventors

• Cunningham John E
• Yao Jin
• Shubin Ivan
• Li Guoliang
• Zheng Xuezhe
• Lin Shiyun
• Thacker Hiren D
• Djordjevic Stevan S
• Krishnamoorthy Ashok V

Classifications

• H10P30/204

  into Group IV semiconductors · CPC title

• H10P30/21

  of electrically active species · CPC title

• H10F77/413

  directly associated or integrated with the devices, e.g. back reflectors (directly associated or integrated with photovoltaic cells H10F77/42) · CPC title

• H01L31/02327

  Electricity · mapped topic

• G02F1/025 Primary

  in an optical waveguide structure (G02F1/017, {G02F1/2257} take precedence) · CPC title