WO2015154307A1

WO2015154307A1 - Graphene-based electro-absorption optical modulator and method for manufacture thereof

Info

Publication number: WO2015154307A1
Application number: PCT/CN2014/075191
Authority: WO
Inventors: 王健; 胡晓; 贺继方
Original assignee: 华为技术有限公司
Priority date: 2014-04-11
Filing date: 2014-04-11
Publication date: 2015-10-15
Also published as: CN105849627A; CN105849627B

Abstract

Provided are a graphene-based electro-absorption optical modulator and a method for manufacturing same. The optical modulator is fabricated on a substrate (10), comprising a graphene-based long-range SPP waveguide structure, a first electrode (301), a second electrode (302), an optical input terminal, and an optical output terminal; the graphene-based long-range SPP waveguide structure comprises, sequentially formed on the substrate (10), a first high refractive index material layer (201), a first graphene layer (202), a first low refractive index material layer (203), a metal film layer (204), a second low refractive index material layer (205), a second graphene layer (206), and a second high refractive index material layer (207). The optical modulator is based on two waveguide structures - a long-range SPP waveguide and a dielectric loaded SPP waveguide - and therefore has the advantages of large modulation depth, small insertion loss, high quality factor, and strong limiting effect on the light field. The method for manufacturing the graphene-based electro-absorption optical modulator is simple and suitable for large-scale production.

Description

Graphene-based electroabsorption optical modulator and preparation method thereof

The present invention relates to the field of graphene application and optical communication technology, and in particular to a graphene-based electroabsorption optical modulator and a preparation method thereof. Background technique

In optoelectronic integrated circuits, optical modulators are one of the most important integrated devices, converting electrical signals into high-rate optical data. Graphene-based optical modulators have attracted much attention due to their strong interaction with light and graphene; large bandwidth; high operating speed, insensitivity to ambient temperature, and compatibility with current CMOS processes.

However, the current graphene-based optical modulator still has problems such as small modulation depth, large insertion loss, and low quality factor. It cannot simultaneously have a large modulation depth, a small insertion loss, a high quality factor, and a strong restriction on the light field. The advantages are therefore not dominant on optical interconnects on highly integrated chips. Summary of the invention

In view of this, the first aspect of the embodiments of the present invention provides a graphene-based electroabsorption optical modulator for solving the problem that the graphene-based optical modulator in the prior art cannot simultaneously have a large modulation depth and a small insertion loss. , high quality factor, high performance problems such as strong restrictions on the light field.

In a first aspect, an embodiment of the present invention provides a graphene-based electroabsorption optical modulator fabricated on a substrate, including a graphene-based long-range SPP waveguide structure formed on the substrate, And a first electrode, a second electrode, an optical input end, and a light output end;

The graphene-based long-range SPP waveguide structure is a multilayer structure including a first high refractive index material layer, a first graphene layer, a first low refractive index material layer, and a metal thin film sequentially formed on the substrate a layer, a second low refractive index material layer, a second graphene layer and a second high refractive index material layer; the first high refractive index material layer and the second high refractive index material layer are made of a refractive index of 2.5- a high refractive index material of 4, wherein the first low refractive index material layer and the second low refractive index material layer are made of a low refractive index material having a refractive index of 1.0 to 2.2, and the metal thin film layer is made of gold, Silver, aluminum or copper;

The graphene-based long-range SPP waveguide structure includes a first direction and a second direction that are parallel to the substrate and perpendicular to each other, and have oppositely disposed ends in the first direction, wherein one end and the light input The other end is connected to the light output end, and in the second direction, the first graphene layer and the second graphene layer are protruded from the graphene-based long-range SPP waveguide An extended end of the structure, the first electrode is formed on an extended end of the first graphene layer, and the second electrode is formed on an extended end of the second graphene layer.

In an embodiment of the invention, the high refractive index material is gallium arsenide or silicon.

In an embodiment of the invention, the low refractive index material is silicon dioxide or silicon nitride.

In an embodiment of the invention, the first high refractive index material layer has a thickness of 50-500 nm, and the second high refractive index material layer has a thickness of 50-500 nm.

In an embodiment of the invention, the first high refractive index material layer and the second high refractive index material layer have the same thickness.

In an embodiment of the invention, the graphene in the first graphene layer and the second graphene layer is a single layer or a plurality of layers of graphene.

In an embodiment of the invention, the first graphene layer has a thickness of 0.35 to 3.5 nm, and the second graphene layer has a thickness of 0.35 to 3.5 nm.

In an embodiment of the invention, the first low refractive index material layer has a thickness of 1-1 nm, and the second low refractive index material layer has a thickness of 1-1 nm.

In an embodiment of the invention, the first low refractive index material layer and the second low refractive index material The thickness of the layers is the same.

In an embodiment of the invention, the thickness of the metal thin film layer is 5-80 nm.

In an embodiment of the invention, the first high refractive index material layer, the first low refractive index material layer, the metal thin film layer, the second low refractive index material layer, and the second high refractive index material layer are in the second direction The width is 80-800nm

In an embodiment of the invention, the first graphene layer and the second graphene layer have a width of 400-1800

In the embodiment of the present invention, a distance between the first low refractive index material layer and the first electrode is 500-1000 nm on the first graphene layer, and on the second graphene layer, The distance between the second high refractive index material layer and the second electrode is 500~1000 nm

In an embodiment of the invention, an extended end of the first graphene layer is formed on the substrate, and an extended end of the second graphene layer is formed on the substrate.

In an embodiment of the invention, the second high refractive index material layer further includes a silicon dioxide layer covering the graphene-based long-range SPP waveguide structure.

The graphene-based electroabsorption optical modulator provided by the first aspect of the present invention has the advantages of large modulation depth, small insertion loss, high quality factor, and strong restriction on the optical field, which is due to the optical of the present invention. The graphene-based long-range SPP waveguide structure in the modulator includes two SPP waveguide structures: long-range SPP waveguide and dielectric-loaded SPP waveguide, which can achieve small insertion loss by using long-range SPP waveguide, and can be realized by using dielectric-loaded SPP waveguide. The distribution of the light field pattern limits the light field to a very narrow area, so that the maximum absorption of light can be achieved by inserting graphene into the area.

In a second aspect, an embodiment of the present invention provides a method for preparing a graphene-based electroabsorption optical modulator, including the following steps: Taking a substrate, depositing a first high refractive index material layer on the substrate, and subsequently transferring a graphene film to form a first graphene layer on the first high refractive index material layer, in the first graphite Depositing a layer of a first low refractive index material on the olefin layer, the first graphene layer comprising an extended end protruding from a side of the first low refractive index material layer, prepared at an extended end of the first graphene layer The conductive metal film forms a first electrode;

Preparing a metal thin film layer on the first low refractive index material layer, then depositing a second low refractive index material layer on the metal thin film layer, and transferring a graphene film at the second low refractive index Forming a second graphene layer on the material layer, depositing a second high refractive index material layer on the second graphene layer, the second graphene layer including protruding from the side of the second high refractive index material layer Extending end, depositing a conductive metal film on the extended end of the second graphene layer to form a second electrode;

The first high refractive index material layer and the second high refractive index material layer are made of a high refractive index material having a refractive index of 2.5-4, the first low refractive index material layer and the second low refractive index The material layer is made of a low refractive index material having a refractive index of 1.0-2.2, and the metal thin film layer is made of gold, silver, aluminum or copper; the first high refractive index material layer, the first graphene layer, the first The low refractive index material layer, the metal thin film layer, the second low refractive index material layer, the second graphene layer, and the second high refractive index material layer constitute a graphene-based long-range SPP waveguide structure, the graphene-based long-range SPP waveguide The structure includes a first direction and a second direction that are parallel to the substrate and perpendicular to each other, and have opposite ends disposed in the first direction, one end of which is connected to the light input end, and the other end and the light output end Connected to obtain a graphene-based electroabsorption optical modulator.

A method for preparing a graphene-based electroabsorption optical modulator according to a second aspect of the present invention has a simple process and is suitable for large-scale production.

In summary, the graphene-based electroabsorption optical modulator provided by the first aspect of the present invention has the advantages of large modulation depth, small insertion loss, high quality factor, and strong restriction on the light field. Because the graphene-based long-range SPP waveguide structure in the optical modulator of the present invention includes two SPP waveguide structures: a long-range SPP waveguide and a dielectric-loaded SPP waveguide, and a small insertion loss can be realized by using a long-range SPP waveguide, and a dielectric-loaded SPP is utilized. The waveguide can achieve a strong light field mode distribution limitation, so that the light field is localized in a very narrow area, so that the maximum absorption of light can be achieved after inserting graphene into the region. A method for preparing a graphene-based electroabsorption optical modulator according to a second aspect of the present invention has a simple process and is suitable for large-scale production.

The advantages of the embodiments of the present invention will be set forth in part in the description which follows. DRAWINGS

1 is a cross-sectional view of a graphene-based electroabsorption optical modulator taken along a second direction in accordance with an embodiment of the present invention;

2 is a simulation result of a graphene-based electroabsorption optical modulator according to Embodiment 1 of the present invention - a mode field distribution diagram;

3 is a simulation result of a graphene-based electroabsorption optical modulator according to a second embodiment of the present invention - a mode field distribution diagram. detailed description

The following are the preferred embodiments of the embodiments of the present invention, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the embodiments of the present invention. And retouching is also considered to be the scope of protection of the embodiments of the present invention.

A first aspect of the embodiments of the present invention provides a graphene-based electroabsorption optical modulator for solving the problem that the graphene-based optical modulator in the prior art cannot have both a large modulation depth and a small insertion loss. A high quality factor, a high performance problem such as a strong restriction on the light field.

In a first aspect, an embodiment of the present invention provides a graphene-based electroabsorption optical modulator fabricated on a substrate, including: a graphene-based long-range SPP waveguide structure formed on the substrate a first electrode, a second electrode, an optical input end, and a light output end;

The graphene-based long-range SPP waveguide structure is a multilayer structure including a first high refractive index material layer, a first graphene layer, a first low refractive index material layer, and a metal thin film layer sequentially formed on the substrate. a second low refractive index material layer, a second graphene layer and a second high refractive index material layer; the first high refractive index material layer and the second high refractive index material layer are made of a refractive index of 2.5-4 The high refractive index material, the first low refractive index material layer and the second low refractive index material layer are made of a low refractive index material having a refractive index of 1.0-2.2, and the metal thin film layer is made of gold or silver. , aluminum or copper;

In an embodiment of the invention, the graphene in the first graphene layer and the second graphene layer is a single Layer or multilayer graphene.

In an embodiment of the invention, the first graphene layer has a thickness of 0.35-3.5 nm, and the second graphene layer has a thickness of 0.35-3.5 nm.

In an embodiment of the invention, the first low refractive index material layer has a thickness of 1-1 nm, and the second low refractive index material layer has a thickness of 1-1 nm. In a certain embodiment of the present invention, the first low refractive index material layer has a thickness of 2-12 nm.

In an embodiment of the invention, the first low refractive index material layer and the second low refractive index material layer have the same thickness.

In an embodiment of the invention, the metal thin film layer has a thickness of 5 to 80 nm. In a certain embodiment of the present invention, the thickness of the metal thin film layer is 10-60 nm.

When the thickness of the first high refractive index material layer and the second high refractive index material layer are the same, and the thicknesses of the first low refractive index material layer and the second low refractive index material layer are also the same, the graphene-based long-range SPP waveguide structure of the present invention For a strictly symmetrical structure, the modulator performs best at this time. However, the long-range SPP waveguide structure based on graphene of the present invention still has excellent performance when it is a non-strict symmetrical structure.

The graphene-based electroabsorption optical modulator of the invention has no strict requirements on the size, and can be prepared according to actual needs. The larger the size, the stronger the limitation of the light field, but the volume increase is not favorable for the on-chip. Highly integrated.

In the embodiment of the present invention, the first low refractive index material layer and the first graphene layer The distance between the first electrodes is 500 to 1000 nm, and the distance between the second high refractive index material layer and the second electrode is 500 to 1000 nm on the second graphene layer. This distance (500~1000 nm) is maintained so that the presence of the electrodes does not affect the distribution of the light field in the waveguide.

In an embodiment of the invention, the second high refractive index material layer further includes a silicon dioxide layer covering the graphene-based long-range SPP waveguide structure. At this time, the graphene-based electroabsorption optical modulator of the present invention is a buried structure, and the silicon dioxide layer can protect the internal waveguide structure.

In an embodiment of the invention, the substrate is an insulating material and may be a silicon dioxide substrate.

The present invention provides a graphene-based electroabsorption optical modulator having a novel structure of a long-range dielectric-loaded surface plasmon-polarized silicon-based optical waveguide. The structure is based on two known SPP waveguides, and one is a long-range surface plasma. The body-polarized waveguide has a millimeter-scale propagation distance, but the limiting effect on light is very weak. The other is a dielectric-loaded SPP waveguide, which has good mode limitation, but the light attenuation is very powerful, so the propagation The distance is very short. The combination of the two structures can achieve both good light limiting effect and small mode propagation attenuation, because the long insertion SPP waveguide can achieve small insertion loss, and the dielectric loaded SPP waveguide can achieve stronger The distribution of the light field pattern limits the light field to a very narrow area, so that the maximum absorption of light can be achieved by inserting graphene into the area. Specifically, the optical modulator of the present invention uses a high refractive index-low refractive index-metal-low refractive index-high refractive index structure, and inserts graphene at a high and low refractive index interface to achieve maximum absorption of light. Since the optical modulator of the present invention uses high and low refractive index and metal structure, SPP is formed in a low refractive index region, and a good local field of the light field is here, and the slit has a very strong limiting effect on the light field.

The working principle of the graphene-based electroabsorption optical modulator of the embodiment of the invention: The voltage on the metal electrode regulates the electrical conductivity of the graphene, and then changes the absorption intensity of the graphene to light; when the applied voltage is at a low voltage, the absorption intensity of the graphene is large, and the light passing rate is very low. The "off" of light is realized. When the applied voltage is large, the absorption of light by graphene is weak, and most of the light is passed, and the "on" of light is realized, and then the information signal of the electric signal is converted into an optical signal. .

The graphene-based electroabsorption optical modulator provided by the first aspect of the present invention has a large modulation depth, a small insertion loss, a high quality factor, and a strong limiting effect on the light field, which is because the optical modulator of the present invention is based on graphite. The long-range SPP waveguide structure of the olefin includes two SPP waveguide structures: long-range SPP waveguide and dielectric-loaded SPP waveguide. Small insertion loss can be realized by long-range SPP waveguide, and strong optical field mode distribution can be realized by dielectric-loaded SPP waveguide. Restriction, so that the field of light field is in a very narrow area, so that the maximum absorption of light can be achieved after inserting graphene into the area.

In a second aspect, an embodiment of the present invention provides a method for preparing a graphene-based electroabsorption optical modulator, including the following steps:

Taking a substrate, depositing a first high refractive index material layer on the substrate, and subsequently transferring a graphene film to form a first graphene layer on the first high refractive index material layer, in the first graphite Depositing a layer of a first low refractive index material on the olefin layer, the first graphene layer comprising an extended end protruding from a side of the first low refractive index material layer, prepared at an extended end of the first graphene layer The conductive metal film forms a first electrode;

Preparing a metal thin film layer on the first low refractive index material layer, then depositing a second low refractive index material layer on the metal thin film layer, and transferring a graphene film at the second low refractive index Forming a second graphene layer on the material layer, depositing a second high refractive index material layer on the second graphene layer, the second graphene layer including protruding from the side of the second high refractive index material layer Extending end, depositing a conductive metal film on the extended end of the second graphene layer to form a second electrode; The first high refractive index material layer and the second high refractive index material layer are made of a high refractive index material having a refractive index of 2.5-4, the first low refractive index material layer and the second low refractive index The material layer is made of a low refractive index material having a refractive index of 1.0-2.2, and the metal thin film layer is made of gold, silver, aluminum or copper; the first high refractive index material layer, the first graphene layer, the first The low refractive index material layer, the metal thin film layer, the second low refractive index material layer, the second graphene layer, and the second high refractive index material layer constitute a graphene-based long-range SPP waveguide structure, the graphene-based long-range SPP waveguide The structure includes a first direction and a second direction that are parallel to the substrate and perpendicular to each other, and have opposite ends disposed in the first direction, one end of which is connected to the light input end, and the other end and the light output end Connected to obtain a graphene-based electroabsorption optical modulator.

The conductive metal film may be gold, aluminum and/or platinum.

The embodiments of the present invention are further described below in various embodiments. The embodiments of the present invention are not limited to the specific embodiments below. Changes can be implemented as appropriate within the scope of the invariable principal rights.

A graphene-based electroabsorption optical modulator fabricated on a substrate 10, comprising: a graphene-based long-range SPP waveguide structure formed on a substrate 10, a first electrode 301, and a second electrode 302 , optical input end and optical output end;

Wherein, the graphene-based long-range SPP waveguide structure is a multi-layer structure including a first high refractive index material layer 201, a first graphene layer 202, a first low refractive index material layer 203, and a metal sequentially formed on the substrate 10. Thin film layer 204, second low refractive index material layer 205, second graphene layer 206, and second high refractive index material layer 207; graphene-based long-range SPP waveguide structure includes a first direction parallel to substrate 10 and perpendicular to each other (I) and the second direction (II) having oppositely disposed ends in the first direction (I), wherein one end is connected to the optical input end, and the other end is connected to the optical output end, in the second direction (II) )on, The first graphene layer 202 and the second graphene layer 206 include extension ends protruding in opposite directions from the graphene-based long-range SPP waveguide structure, and the first electrode 301 is formed on the extended end of the first graphene layer 202, second The electrode 302 is formed on the extended end of the second graphene layer 206. In the present embodiment, the extended end of the first graphene layer 202 is formed on the substrate 10, and the extended end of the second graphene layer 206 is formed on the substrate. 10 on.

Embodiment 1

The method for preparing the above graphene-based electroabsorption optical modulator comprises the steps of: taking a silicon dioxide substrate, and preparing a thickness of 200 nm and a width (width in the second direction) by using an atomic layer deposition technique on the substrate. a 200 nm gallium arsenide (GaAs) layer, that is, a first high refractive index material layer is obtained, and then a graphene film having a thickness of 0.7 nm is transferred to form a first graphene layer on the gallium arsenide layer, A layer of silicon dioxide having a thickness of 2 nm and a width of 200 nm is prepared by using an atomic layer deposition technique on a graphene layer to obtain a first low refractive index material layer, and the first graphene layer includes a first low refractive index. a metal layer on one side of the material layer and formed on the extended end of the substrate, a metal platinum film is prepared on the extended end of the first graphene layer by magnetron sputtering, and a gold film is formed on the metal platinum film to form a first electrode; The distance between the first low refractive index material layer and the first electrode is 500 nm;

Preparing a metal silver (Ag) thin film layer having a thickness of 20 nm and a width of 200 nm on the first low refractive index material layer by magnetron sputtering, and then depositing an atomic layer on the metallic silver thin film layer The second layer of the low refractive index material is obtained by preparing a layer of silicon dioxide (SiO ₂ ) having a thickness of 2 nm and a width of 200 nm, and then transferring a graphene film having a thickness of 0.7 nm to form a layer of the second low refractive index material. a second graphene layer is formed on the second graphene layer by a layer deposition technique to prepare a gallium arsenide layer having a thickness of 200 nm and a width of 200 nm, thereby obtaining a second high refractive index material layer, and the second graphene layer The method comprises: forming an extension end formed on one side of the second high refractive index material layer and formed on the substrate, and preparing a metal platinum film on the extended end of the second graphene layer by magnetron sputtering, and then on the metal platinum film Preparation of gold film shape a second electrode; a distance between the second high refractive index material layer and the second electrode is 500 nm; a first high refractive index material layer, a first graphene layer, a first low refractive index material layer, a metal thin film layer, The second low refractive index material layer, the second graphene layer and the second high refractive index material layer constitute a graphene-based long-range SPP waveguide structure, and the graphene-based long-range SPP waveguide structure includes a first direction parallel to the substrate and perpendicular to each other And a second direction, having opposite ends disposed in the first direction, one end is connected to the light input end, and the other end is connected to the light output end to obtain a graphene-based electroabsorption optical modulator.

The graphene-based optical modulator of the embodiment of the invention first adds a low refractive index material between the high refractive index material and the metal thin film; and the light is confined in the low refractive index material region due to the oscillation of the electron on the metal surface. Therefore, SPP is formed, so that the light is confined to a small-sized low-refractive-index material region (in the slit S shown in FIG. 1), so that the strongest portion of the light field is sufficiently contacted with the graphene to achieve a good modulation effect. . Since the light is well limited between the high refractive index material and the metal, that is, the low refractive index material silica, if the graphene is inserted at the interface of the high and low refractive index, the graphene is energized and adjusted to some A suitable voltage can achieve a good absorption of light, and then achieve a larger modulation depth; adjust to another suitable voltage, allowing light to pass, and low insertion loss, thus achieving the amplitude of the light modulation. That is, it is possible to solve the problem that the insertion loss is small while achieving a large modulation depth.

Embodiment 2

A method for preparing a graphene-based electroabsorption optical modulator comprises the steps of: taking an SOI substrate, removing excess Si by an ICP etching technique, and obtaining an elemental silicon layer having a thickness of 200 nm and a width of 200 nm, ie, a layer of high refractive index material, followed by transferring a graphene film having a thickness of 0.7 nm to form a first graphene layer on the elemental silicon layer, and using a layer deposition technique on the first graphene layer to have a thickness of 2 nm and a width of a 200 nm silicon dioxide layer, that is, a first low refractive index material layer is obtained, the first graphene layer including a side protruding from the first low refractive index material layer and formed on the substrate Forming a metal platinum film on the extended end of the first graphene layer to form a first electrode by using a magnetron sputtering method; a distance between the first low refractive index material layer and the first electrode is 500 nm;

金属 a method of magnetron sputtering is used to prepare a metal silver thin film layer with a thickness of 20 nm and a width of 200 nm on the first low refractive index material layer, and then a thickness is prepared on the metallic silver thin film layer by atomic layer deposition technique. 2 nm, a silicon dioxide layer having a width of 200 nm, that is, a second low refractive index material layer is obtained, and then a graphene film having a thickness of 0.7 nm is transferred to form a second graphene layer on the second low refractive index material layer. On the second graphene layer, an elemental silicon layer having a thickness of 200 nm and a width of 200 nm is prepared by an atomic layer deposition technique, that is, a second high refractive index material layer is obtained, and the second graphene layer includes a second high refractive index. a metal layer on one side of the material layer and formed on the extended end of the substrate, and a metal platinum film is formed on the extended end of the second graphene layer by magnetron sputtering to form a second electrode; the second high refractive index material layer and the second layer The large separation between the electrodes is 500 nm;

The first high refractive index material layer, the first graphene layer, the first low refractive index material layer, the metal thin film layer, the second low refractive index material layer, the second graphene layer, and the second high refractive index material layer are formed based on graphite The long-range SPP waveguide structure of the olefin, the graphene-based long-range SPP waveguide structure includes a first direction and a second direction that are parallel to the substrate and perpendicular to each other, and have opposite ends disposed in the first direction, and one end and the light input The end phase is connected, and the other end is connected to the light output end to obtain a graphene-based electroabsorption optical modulator.

Effect embodiment

In order to strongly support the beneficial effects of the embodiments of the present invention, effects are provided, for example, to evaluate the performance of the products provided by the embodiments of the present invention.

The graphene-based electroabsorption optical modulator of Example 1 was simulated using COMSOL-RF module-mixed mode wave, and two representative chemical potentials were given, namely μ=0.512εν, μ=0.405εν The corresponding mode distribution is as shown in (a) and (c) of Fig. 2 to achieve modulation of light. The simulation yields the following results:

When μ=0.512εν, the modulator is in the off state, and the effective modulus of the mode obtained by the simulation result is: 3.16774+0.313423i, and the relationship between the propagation length L and the effective modulus imaginary part k is used to find L= 0.39374 m, thus obtaining a modulation depth of approximately: MD=11.251 (1Β/μπι.

When μ=0.405εν, the modulator is in the on state, and the effective modulus of the mode obtained by the simulation result is: 2.27758+9.531512xl (T ⁴ i, using the relationship between the propagation length L and the effective modulus imaginary part k Let L=162.6185 m be obtained, and the modulation depth is about 0.034 (1Β/μπι, ie, insertion loss IL=0.034άΒ/μπι _ο

In Fig. 2, (b) is an enlarged view of the graphene-based long-range SPP waveguide structure in the middle region of (a). This is a simulation result diagram. By comparing with the device parameter map (Fig. 1), the specific part of the material and its SPP are known. The light field distribution, as shown in Fig. 2, shows that the light field is well limited in the low refractive index material silica, that is, the local area is in the slit S, and the mode field is very local.

The quality factor is defined as: extinction ratio / insertion loss (MD/IL), resulting in a quality factor of 330. At the same time, the bandwidth under this parameter is calculated to be ~15THz. The graphene-based electroabsorption optical modulator of the second embodiment was simulated using COMSOL-RF module-mixed mode wave, and two representative chemical potentials were given, namely μ=0.512εν, μ=0.405εν. The corresponding mode distribution is as shown in (a) and (c) of Fig. 3 to achieve modulation of light.

The simulation yields the following results:

When μ=0.512εν (should be 0.512eV), the modulator is in the off state, and the effective modulus of the TM mode is: 3.127246+0.302853i, using the propagation length L and the effective modulus imaginary part k The relational formula finds a modulation depth of approximately Μϋ=10.6634 (1Β/μπι.

When μ=0.405εν, the modulator is in the on state, and the effective modulus of the mode is obtained from the simulation result. For: 2.249087+9.232964xl (T ⁴ i, the modulation depth is obtained by using the relation between the propagation length L and the effective modulus imaginary part k: 0.0325 (1Β/μπι, ie, insertion loss IL=0.0325dB m.

In Fig. 3, (b) is an enlarged view of the middle region of (a). The specific part of the material and its SPP light field distribution are compared with the device parameter map (Fig. 1). Figure 201 (b) is the first. The high refractive index material layer 204 is a metal thin film layer, 205 is a second low refractive index material layer 206, and is a second graphene layer. As shown in FIG. 3, the light field is well limited to the low refractive index material. In silicon, that is, the local area is in the slit S, the mode field is very local.

The quality factor is defined as: extinction ratio / insertion loss (MD/IL), resulting in a quality factor of 330. At the same time, the bandwidth under this parameter is calculated to be ~15THz.

Claims

Rights request

1. A graphene-based electroabsorption optical modulator, which is fabricated on a substrate, and is characterized in that it includes a graphene-based long-range SPP waveguide structure formed on the substrate, and a first electrode , the second electrode, the light input end and the light output end;

The graphene-based long-range SPP waveguide structure is a multi-layer structure, including a first high refractive index material layer, a first graphene layer, a first low refractive index material layer, and a metal film layer sequentially formed on the substrate. , a second low refractive index material layer, a second graphene layer and a second high refractive index material layer; the material of the first high refractive index material layer and the second high refractive index material layer has a refractive index of 2.5-4 high refractive index material, the first low refractive index material layer and the second low refractive index material layer are made of low refractive index material with a refractive index of 1.0-2.2, and the material of the metal thin film layer is gold, silver , aluminum or copper;

The graphene-based long-range SPP waveguide structure includes a first direction and a second direction parallel to the substrate and perpendicular to each other, and has two opposite ends in the first direction, one end of which is connected to the light input One end is connected to the other end and the other end is connected to the light output end. In the second direction, the first graphene layer and the second graphene layer include protruding from the graphene-based long-range SPP waveguide. On the extended end of the structure, the first electrode is formed on the extended end of the first graphene layer, and the second electrode is formed on the extended end of the second graphene layer.

2. The graphene-based electroabsorption optical modulator according to claim 1, wherein the high refractive index material is gallium arsenide or silicon.

3. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 2, wherein the low refractive index material is silicon dioxide or silicon nitride.

4. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 3, wherein the thickness of the first high refractive index material layer is 50-500 nm, and the second high refractive index material layer has a thickness of 50-500 nm. rate material layer The thickness is 50-500nm

5. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 4, wherein the first high refractive index material layer and the second high refractive index material layer have the same thickness. .

6. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 5, wherein the graphene in the first graphene layer and the second graphene layer is a single layer or multiple layers. layer of graphene.

7. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 6, wherein the thickness of the first graphene layer is 0.35-3.5 nm, and the thickness of the second graphene layer The thickness is 0.35-3.5nm

8. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 7, wherein the thickness of the first low refractive index material layer is 1-15 nm, and the second low refractive index material layer has a thickness of 1-15 nm. The thickness of the rate material layer is 1-15

9. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 8, wherein the first low refractive index material layer and the second low refractive index material layer have the same thickness. .

10. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 9, characterized in that the thickness of the metal film layer is 5-80nm.

11. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 10, characterized in that, the first high refractive index material layer, the first low refractive index material layer, and the metal film layer, The width of the second low refractive index material layer and the second high refractive index material layer in the second direction is 80-800nm.

12. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 11, wherein the width of the first graphene layer and the second graphene layer is 400-1800 nm.

13. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 12, wherein on the first graphene layer, the first low refractive index material layer and the third The distance between an electrode is 500~1000nm. On the second graphene layer, the second high refractive index material layer and the third The distance between the two electrodes is 500~1000nm.

14. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 13, wherein the extended end of the first graphene layer is formed on the substrate, and the second Extended ends of the graphene layer are formed on the substrate.

15. The graphene-based electroabsorption optical modulator according to any one of claims 1 to 14, characterized in that, on the second high refractive index material layer, it further includes a long-range layer covering the graphene-based material layer. Silicon dioxide layer of SPP waveguide structure.

16. A method for preparing a graphene-based electroabsorption optical modulator, which is characterized by including the following steps:

Take a substrate, deposit and prepare a first high refractive index material layer on the substrate, then transfer a graphene film to form a first graphene layer on the first high refractive index material layer, and then deposit the first graphene layer on the first high refractive index material layer. A first low refractive index material layer is deposited on the graphene layer. The first graphene layer includes an extended end protruding from one side of the first low refractive index material layer. At the extended end of the first graphene layer Preparing a conductive metal film to form a first electrode;

Prepare a metal thin film layer on the first low refractive index material layer, then deposit a second low refractive index material layer on the metal thin film layer, and then transfer a graphene film to the second low refractive index material layer. A second graphene layer is formed on the material layer, and a second high refractive index material layer is deposited on the second graphene layer. The second graphene layer includes a side protruding from the second high refractive index material layer. The extended end of the second graphene layer is deposited with a conductive metal film to form a second electrode;

The material of the first high refractive index material layer and the second high refractive index material layer is a high refractive index material with a refractive index of 2.5-4, and the first low refractive index material layer and the second low refractive index material layer The material layer is made of a low refractive index material with a refractive index of 1.0-2.2, the metal film layer is made of gold, silver, aluminum or copper; the first high refractive index material layer, the first graphene layer, the first Low refractive index material layer, metal thin The film layer, the second low refractive index material layer, the second graphene layer and the second high refractive index material layer constitute a graphene-based long-range SPP waveguide structure, and the graphene-based long-range SPP waveguide structure includes a waveguide parallel to the lining. The bottom and mutually perpendicular first and second directions have two opposite ends in the first direction. One end is connected to the light input end and the other end is connected to the light output end. Finally, a graphite-based Electroabsorption optical modulator of ene.