Electro-optical modulator and a method for obtaining an electro-optical modulator

Patent metadata

Field	Value
Publication number	US-11860502-B2
Application number	US-202017113749-A
Country	US
Kind code	B2
Filing date	Dec 7, 2020
Priority date	Dec 5, 2019
Publication date	Jan 2, 2024
Grant date	Jan 2, 2024

Abstract

Provided is an electro-optical modulator, particularly a double layer graphene modulator having an optimized arrangement to provide both a large optical bandwidth and a high optical transmission for light travelling through an optical waveguide of the modulator, wherein at least one of a top and a bottom graphene sheets extends along a X-direction:
above part of the width of the optical waveguide, wherein that part ranges from 50% to 100% of the width of the optical waveguide; or completely above the whole width of the optical waveguide, and beyond through a respective further projecting portion with a length, along the X direction, of up to 25% of the optical waveguide width.

Provided is also a method for obtaining the electro-optical modulator of the invention.

First claim

What is claimed is:

1. An electro-optical modulator, comprising:
a semiconductor substrate;
at least first and second electrodes distanced from each other along an X-direction;
an optical waveguide embedded within and/or arranged on said semiconductor substrate, an upper face of said optical waveguide being located at, below or above a location between said first and second electrodes, along said X-direction, wherein said optical waveguide longitudinally extends along at least a direction transversal to said X-direction;
a bottom graphene sheet arranged and extending along said X-direction over at least a portion of the upper face of the semiconductor substrate, with a first end electrically connected to said first electrode and without the bottom graphene sheet reaching the second electrode;
a sheet of a first dielectric material extending over said bottom graphene sheet;
a top graphene sheet arranged and extending along said X-direction over at least a portion of said sheet of a first dielectric material, with a first end electrically connected to said second electrode and without the top graphene sheet reaching the first electrode; and
a second dielectric material, which is a two-dimensional material with at least dielectric properties different to the dielectric properties of said first dielectric material, said second dielectric material covering:
upper and bottom faces of said top graphene sheet and/or an upper face of said bottom graphene sheet; or
upper and bottom faces of said top graphene sheet and/or both upper and bottom faces of said bottom graphene sheet;
wherein at least one of said top and bottom graphene sheets extends along said X-direction:
above part of the width of the optical waveguide, wherein said part ranges from 50% to 100% of the width of the optical waveguide; or
completely above the whole width of the optical waveguide, and beyond through a respective further projecting portion with a length, along the X direction, of up to 25% of the optical waveguide width.

2. The electro-optical modulator according to claim 1 , wherein said top graphene sheet extends along said X-direction completely above the whole width of the optical waveguide, and beyond through a respective further projecting portion with a length, along the X direction, of up to 25% of the optical waveguide width.

3. The electro-optical modulator according to claim 1 , wherein said bottom graphene sheet extends along said X-direction completely above the whole width of the optical waveguide, and beyond through a respective further projecting portion with a length, along the X direction, of up to 25% of the optical waveguide width.

4. The electro-optical modulator according to claim 1 , wherein each of the top and bottom graphene sheets extends along the X-direction above part of the width of the optical waveguide, wherein said part ranges from 50% to 100% of the width of the optical waveguide.

5. The electro-optical modulator according to claim 1 , wherein each of the top and bottom graphene sheets extends along the X-direction completely above the whole width of the optical waveguide, and beyond through a respective further projecting portion with a length, along the X direction, of up to 25% of the optical waveguide width.

6. The electro-optical modulator according to claim 1 , wherein at least one of the top and bottom graphene sheets extends along said X-direction from a 75% to a 100% above the optical waveguide width.

7. The electro-optical modulator according to claim 6 , wherein at least one of the top and bottom graphene sheets extend along said X-direction from a 95% to a 100% above the optical waveguide width.

8. The electro-optical modulator according to claim 1 , wherein at least one of the top and bottom graphene sheets extends along said X-direction from a 50% to a 95% above the optical waveguide width.

9. The electro-optical modulator according to claim 1 , wherein at least one of the top and bottom graphene sheets extends along said X-direction completely above the optical waveguide width and beyond through a further projecting portion with a length of up to a 5% of the optical waveguide width.

10. The electro-optical modulator according to claim 1 , wherein:
said sheet of a first dielectric material extends along the X-direction at least within an area overlapped by both the top and the bottom graphene sheets; and
a bottom sheet of said second dielectric material covering the lower face of the top graphene sheet or a top and bottom sheets sandwiching the top graphene sheet, contact the second electrode and extend, along the X-direction, up to at least just above and just below, respectively, a top graphene free edge, and/or
a top sheet of said second dielectric material covering the upper face of the bottom graphene sheet or a top and a bottom sheets of the second dielectric material sandwiching the bottom graphene sheet, contact the first electrode and extend, along the X-direction, up to at least just above or just above and just below, respectively, a bottom graphene free edge.

11. The electro-optical modulator according to claim 10 , wherein, regarding the different sheets of the second dielectric material:
the thickness of the top sheet sandwiching, together with the bottom sheet, the top graphene sheet, ranges from 0 to 200 nm;
the thickness of the bottom sheet sandwiching, together with the top sheet, the bottom graphene sheet, ranges from 0 nm to 10 nm; and
the thickness of the bottom sheet sandwiching, together with the top sheet, the top graphene sheet, added to the thickness of the top sheet sandwiching, together with the bottom sheet, the bottom graphene sheet, ranges from 2 nm to 40 nm.

12. The electro-optical modulator according to claim 1 , wherein the total dielectric thickness, including the thickness of the sheet of a first dielectric material and the thickness of the second dielectric material, ranges from 9 nm to 30 nm.

13. The electro-optical modulator according to claim 1 , wherein the thickness of the sheet of a first dielectric material ranges from a 10% to a 200% with respect to the thickness of the second dielectric material.

14. The electro-optical modulator according to claim 13 , wherein the thickness of the sheet of a first dielectric material is different to the thickness of the second dielectric material.

15. The electro-optical modulator according to claim 1 , wherein:
said first dielectric material is at least one of the following materials, or a combination thereof: HfO 2 , SiO 2 , Si 3 N 4 , Al 2 O 3 , ZrO 2 , TiO 2 , TiN, HfSiO 4 , ZrSiO 4 , Calcium Copper Titanate, Barium Titanate, Strontium Titanate, Barium Strontium Titanate, Polystyrene, Polypropylene, Polyamide, Polyethylene, and Polytetrafluoroethylene; and
said second dielectric material is at least one of the following 2D layered materials, or a combination thereof: hBN, MoTe 2 , WSe 2 , WS 2 , graphene, MoS 2 , MoSe 2 , WS 2 , WSe 2 , black phosphorus, and SnS 2 .

16. The electro-optical modulator according to claim 1 , which implements a Mach-Zehnder interferometer based arrangement, wherein said optical waveguide is a first optical waveguide branch, the modulator further comprising:
a second optical waveguide branch distanced from the first optical waveguide branch along the X-direction and embedded within and/or arranged on the semiconductor substrate, wherein said second optical waveguide branch longitudinally extends along at least the direction transversal to the X-direction; and
a third electrode located distanced from the second electrode along the X-direction, wherein th

Assignees

• Fundacio Inst De Ciencies Fotòniques
• Inst Catalana Recerca Estudis Avancats

Inventors

• Koppens Frank
• Terrés Bernat
• Agarwal Hitesh

Classifications

• G02F1/2257 Primary

  the optical waveguides being made of semiconducting material · CPC title

• G02F1/212

  Mach-Zehnder type · CPC title

• G02F2202/42

  Materials having a particular dielectric constant · CPC title

• G02F1/035 Primary

  in an optical waveguide structure · CPC title

• G02F1/025 Primary

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