CN-122018184-A - Electro-optical modulator and preparation method thereof

CN122018184ACN 122018184 ACN122018184 ACN 122018184ACN-122018184-A

Abstract

The invention provides an electro-optical modulator and a preparation method of the electro-optical modulator, wherein a strip waveguide comprises a first coupling area for coupling, straight waveguide areas respectively positioned at two sides of the first coupling area and a graded area positioned between the straight waveguide and the first coupling area, an annular waveguide is in a circular ring shape and comprises a second coupling area for coupling, the second coupling area and the first coupling area are respectively arc sections, the first coupling area and the second coupling area are concentric, a graphene film capacitor is positioned on the surface of the annular waveguide except the second coupling area and used for regulating and controlling the coupling state between the strip waveguide and the annular waveguide, and the coupling state between the strip waveguide and the annular waveguide is in a critical coupling state under the condition that the graphene film capacitor is in zero bias, so that the device size is reduced, the modulation efficiency is improved, and the preparation process difficulty is reduced.

Inventors

ZHANG MIAO
HUANG TINGLING
WANG ZHENG
TIAN ZIAO
FU JIASHENG

Assignees

中国科学院上海微系统与信息技术研究所

Dates

Publication Date: 20260512
Application Date: 20260305

Claims (10)

1. An electro-optic modulator, comprising: The strip waveguide comprises a first coupling region for coupling, straight waveguide regions respectively positioned at two sides of the first coupling region, and a graded region positioned between the straight waveguide and the first coupling region; The annular waveguide is in a circular ring shape and comprises a second coupling area used for being coupled with the first coupling area, wherein the second coupling area and the first coupling area are respectively arc sections, the first coupling area and the second coupling area are concentric, the radius of a circle where the first coupling area is positioned is larger than that of a circle where the second coupling area is positioned, and the distance between the slow-changing area and the annular waveguide is gradually increased or gradually decreased along the transmission direction of light waves; And the graphene film capacitor is positioned on the surface of the area, except the second coupling area, of the annular waveguide and is used for regulating and controlling the coupling state between the strip waveguide and the annular waveguide, wherein the coupling state between the strip waveguide and the annular waveguide is in a critical coupling state under the condition that the graphene film capacitor is in zero bias.
2. The electro-optic modulator of claim 1, wherein the electro-optic modulator comprises a coupling state between the strip waveguide and the ring waveguide in a critical coupling state by controlling a central angle corresponding to the first coupling region and the second coupling region and a coupling pitch between the first coupling region and the second coupling region when the graphene thin film capacitance is at zero bias.
3. An electro-optic modulator as claimed in claim 1 wherein the coupling spacing between the first and second coupling regions is less than or equal to 300 nm.
4. An electro-optic modulator as claimed in claim 1 wherein the graphene film capacitance and the annular waveguide further comprise a cladding layer therebetween.
5. An electro-optic modulator as claimed in claim 4, wherein the graphene thin film capacitor comprises: the first graphene film is positioned in a partial area of the surface of the cladding; the second graphene film is positioned above the first graphene film, a space is arranged between the first graphene film and the second graphene film, and the first graphene film and the second graphene film are partially overlapped; a dielectric layer at least between the first graphene film and the second graphene film; the first electrode is connected with the first graphene film; and the second electrode is connected with the second graphene film.
6. An electro-optic modulator as claimed in claim 5 wherein the material of the dielectric layer comprises hafnium oxide, aluminum oxide, hexagonal boron nitride, calcium fluoride.
7. An electro-optic modulator as claimed in claim 5 wherein the spacing between the first graphene film and the second graphene film is in the range of 10nm to 30nm.
8. The electro-optic modulator of claim 5, wherein the first graphene film comprises a first overlap region for overlapping the second graphene film, a cladding layer on one side of the annular waveguide, and a first edge region connected to the first overlap region, the second graphene film comprises a second overlap region overlapping the first overlap region, a cladding layer on the other side of the annular waveguide, and a second edge region connected to the second overlap region, the first overlap region and the second overlap region are located above the cladding layer in the annular waveguide except for the second coupling region, the first electrode is located at an edge of the first edge region, the second electrode is located at an edge of the second edge region, wherein a first distance between the first electrode and the annular waveguide is 1 micron to 2 microns, a second distance between the second electrode and the annular waveguide is 1 micron to 2 microns, and a second distance between the second electrode and the annular waveguide is equal to a fourth distance between the first electrode and the annular waveguide, the second electrode is equal to a fourth distance between the second overlap region and the annular waveguide, and the fourth edge region is equal to 4 microns.
9. An electro-optic modulator as claimed in claim 5 wherein the material of the first and second electrodes comprises gold or titanium.
10. A method of making an electro-optic modulator comprising: The method comprises the steps of providing a substrate, wherein the substrate comprises a cladding, a strip waveguide and an annular waveguide, the strip waveguide and the annular waveguide are positioned in the cladding, the strip waveguide comprises a first coupling area for coupling, straight waveguide areas respectively positioned at two sides of the first coupling area and a gradual change area positioned between the straight waveguide and the first coupling area, the annular waveguide comprises a second coupling area for coupling with the first coupling area in a circular ring shape, the second coupling area and the first coupling area are respectively arc sections, the first coupling area and the second coupling area are concentric, the radius of a circle where the first coupling area is positioned is larger than the radius of a circle where the second coupling area is positioned, and the distance between the gradual change area and the annular waveguide is gradually increased or gradually decreased along the transmission direction of light waves; Forming a graphene film capacitor on the surface of a cladding layer of the annular waveguide except the second coupling region, wherein the graphene capacitor is used for regulating and controlling the coupling state between the strip waveguide and the annular waveguide; wherein the forming of the graphene film capacitor on the cladding surface of the region except the second coupling region in the annular waveguide includes: Forming a first graphene film on the cladding surface of the annular waveguide in a region except the second coupling region; forming a first electrode on the first graphene film; Forming a dielectric layer on the first electrode, the first graphene film and the substrate; forming a second graphene film on the dielectric layer; and forming a second electrode on the second graphene film.

Description

Electro-optical modulator and preparation method thereof Technical Field The present invention relates to the field of semiconductors, and in particular, to an electro-optical modulator and a method for manufacturing the electro-optical modulator. Background Electro-optic modulators play a key role in the leading edge fields of optical communication networks, quantum optics, high performance computing systems, and the like. The current widely used silicon-based electro-optic modulator is limited by the weak plasma dispersion effect and free carrier absorption characteristic of the silicon material, and generally has the problem of low modulation efficiency, and the size of the device is usually in millimeter order to achieve enough modulation depth. In order to achieve both high modulation efficiency and small device size, a micro-ring resonator can be used as a core modulation unit in the prior art. Compared with a millimeter-scale Mach-Zehnder interferometer (MZI, mach-Zehnder interferometer) structure, the micro-ring resonator can be reduced to a micrometer level in size, and the integration potential of the device is greatly improved. However, when the coupling distance between the micro-ring resonator and the straight waveguide is too small, the difficulty of the manufacturing process of the device is significantly increased. Therefore, how to improve the modulation efficiency of the electro-optical modulator, reduce the size of the device, and reduce the difficulty of the preparation process thereof has become one of the technical problems to be solved currently. It should be noted that the foregoing description of the background art is only for the purpose of providing a clear and complete description of the technical solution of the present application and is presented for the convenience of understanding by those skilled in the art. The above-described solutions are not considered to be known to the person skilled in the art simply because they are set forth in the background of the application section. Disclosure of Invention In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide an electro-optical modulator and a method for manufacturing the electro-optical modulator, which are used for solving the problems that the electro-optical modulator in the prior art cannot achieve the reduction in size, improvement in modulation efficiency, reduction in manufacturing difficulty, and the like. To achieve the above and other related objects, the present invention provides an electro-optical modulator comprising: The strip waveguide comprises a first coupling region for coupling, straight waveguide regions respectively positioned at two sides of the first coupling region, and a graded region positioned between the straight waveguide and the first coupling region; The annular waveguide is in a circular ring shape and comprises a second coupling area used for being coupled with the first coupling area, wherein the second coupling area and the first coupling area are respectively arc sections, the first coupling area and the second coupling area are concentric, the radius of a circle where the first coupling area is positioned is larger than that of a circle where the second coupling area is positioned, and the distance between the slow-changing area and the annular waveguide is gradually increased or gradually decreased along the transmission direction of light waves; And the graphene film capacitor is positioned on the surface of the area, except the second coupling area, of the annular waveguide and is used for regulating and controlling the coupling state between the strip waveguide and the annular waveguide, wherein the coupling state between the strip waveguide and the annular waveguide is in a critical coupling state under the condition that the graphene film capacitor is in zero bias. In one embodiment, the electro-optical modulator comprises a critical coupling state of the coupling state between the strip waveguide and the annular waveguide by controlling the central angles corresponding to the first coupling region and the second coupling region and the coupling spacing between the first coupling region and the second coupling region under the condition that the graphene film capacitor is at zero bias. In one embodiment, a coupling pitch between the first coupling region and the second coupling region is less than or equal to 300 nanometers. In one embodiment, a cladding layer is further included between the graphene film capacitor and the annular waveguide. In one embodiment, the graphene thin film capacitor includes: the first graphene film is positioned in a partial area of the surface of the cladding; the second graphene film is positioned above the first graphene film, a space is arranged between the first graphene film and the second graphene film, and the first graphene film and the second graphene film are partially overlapped; a dielectri