CN104078739A - Graphene-based directional coupler - Google Patents
Graphene-based directional coupler Download PDFInfo
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- CN104078739A CN104078739A CN201410363980.1A CN201410363980A CN104078739A CN 104078739 A CN104078739 A CN 104078739A CN 201410363980 A CN201410363980 A CN 201410363980A CN 104078739 A CN104078739 A CN 104078739A
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Abstract
The invention discloses a graphene-based directional coupler, and belongs to the field of photoelectronic technique. The graphene-based directional coupler comprises a first strip loaded waveguide, a second strip loaded waveguide, an insulation layer and a semiconductor substrate layer, wherein the insulation layer is located on the upper surface of the semiconductor substrate layer, the first strip loaded waveguide and the second strip loaded waveguide are parallel and located on the common insulation layer, and a gap between the first strip loaded waveguide and the second strip loaded waveguide is filled with a first dielectric layer, a graphene dielectric layer and a second dielectric layer from left to right; and the graphene dielectric layer is formed by at least three graphene layers which are parallel. The graphene-based directional coupler has high symmetry, and the two waveguides have high phase matching, so that a very high extinction ratio can be achieved at an output end under a reasonable waveguide length; and accordingly, devices such as a light intensity modulator, an optical switch and the like made by using the property has the characteristics of high speed, broad band, low power consumption and small size.
Description
Technical field
The invention belongs to photoelectron technology field, be specifically related to the novel of a kind of high speed, broadband, low-power consumption
Directional coupler based on Graphene.
Background technology
Directional coupler is a kind of common structure in integrated optics.Its principle is in the time of two high index waveguide close proximity, because, can there is the Power Exchange between two waveguides in the effect of evanescent wave, from quantum mechanics angle, low refractive index dielectric between waveguide can be considered as to potential barrier, the Power Exchange of two waveguides is a kind of photon tunneling effect.The directive power divider of directional coupler tool, it can separate by a certain percentage Partial Power from the forward wave of main transmission system, and power-take-off from backward-wave not substantially.Therefore utilize directional coupler to sample respectively the incident wave in main transmission system and reflected wave.Thereby directional coupling structure is widely used in the aspects such as coupling between waveguide, filtering, polarization selection, modulation, optical switch and laser.
The fundamental diagram of directional coupler, as shown in Figure 1, directional coupler can be equivalent to four port networks, comprises two main line ports: radio-frequency (RF) signal input end and radiofrequency signal output, two by-pass ports: radiofrequency signal coupled end and radiofrequency signal isolation end.Line-to-line is by capacitive coupling, and when power is inputted by port radio-frequency (RF) signal input end, a part of power is from straight-through radiofrequency signal output output; Some power is coupled in by-pass, utilizes the field vector stack of each partial wave, make radiofrequency signal coupled end form coupling port, and radiofrequency signal isolation end field vector is oppositely offset formation isolated port.By choose reasonable coupled structure and coupling size, can make the technical indicators such as the degree of coupling, isolation, input vswr, frequency bandwidth of directional coupler reach necessary requirement.The degree of coupling refers to the ratio into the input power of input and the power output of coupled end, by choose reasonable coupled structure and coupling size, can make the technical indicators such as the degree of coupling, isolation, input vswr, frequency bandwidth of directional coupler reach necessary requirement.The degree of coupling refers to the ratio into the input power of input and the power output of coupled end; And isolation refers to the ratio of the input power of input and the power output of isolation end; Directivity refers to the ratio of the power output of coupled end and the power output of isolation end; Input vswr refers to the standing-wave ratio of input port when its excess-three port all connects matched load, and frequency bandwidth refers to the working band width of the directional coupler when degree of coupling, isolation, input vswr all meet the demands.
Graphene is a kind of New Two Dimensional lonsdaleite nano material that obtains in recent years extensive concern, and its properties has very large application prospect on opto-electronic device.Its distinctive zero bandgap structure, can affect the light of very wide wave band, has good broadband character, and Graphene at room temperature have about 200,000cm
2the electron mobility of/Vs, is the more than 100 times of silicon, at present the known the highest material of electron mobility.Meanwhile, under the effect of bias voltage, the optical conductivity of Graphene has significant change, therefore can effectively utilize at modulator, on the opto-electronic devices such as laser.
Application about Graphene in directional coupler is existing research also.The graphene layer inserting between directional coupler two parallel waveguides, can disturb power coupling process therebetween effectively, and coupling coefficient is changed, thereby affects the coupling length of luminous power.(see document Andrea Locatelli, Antonio-Daniele Capobianco, Gianfranco Nalesso, Stefano Boscolo, MicheleMidrioc, Costantino De Angelis, Graphene-based electro-optical control of the beat length of dielectric couplers, Optics Communications 318 (2014) 175 – 179).Utilize this character, load tuning its optical conductivity of electrode on graphene layer, can modulate the coupling length of directional coupler, thereby can make, comprise optical modulator, optical switch is at interior a series of optical devices.Adopt the optical device of this structure, have at a high speed, broadband, low-power consumption, the feature that volume is little, and can be compatible mutually with CMOS technique, potentiality have a wide range of applications.
Summary of the invention
For above-mentioned prior art, the object of the invention is to how to provide a kind of have high speed, wide bandwidth, low-power consumption and can with the CMOS technique compatible novel directional coupler based on Graphene mutually.
In order to solve the problems of the technologies described above, the present invention adopts following technical scheme:
A kind of directional coupler based on Graphene, comprise the first carrier strip waveguide, the second carrier strip waveguide, insulating barrier, semiconductor substrate layer, insulating barrier is positioned at the upper surface of semiconductor substrate layer, it is characterized in that, described the first carrier strip waveguide and the second carrier strip waveguide are parallel to each other and are all positioned on common insulating barrier, between the first carrier strip waveguide and the second carrier strip waveguide, are from left to right filled with successively first medium layer, Graphene dielectric layer and second medium layer; Described Graphene dielectric layer at least consists of three layers of graphene layer being parallel to each other, and described graphene layer is overlapping in whole or in part.
In the present invention, described Graphene dielectric layer mainly consists of the first graphene layer, the first separator, the second graphene layer, the second separator and the 3rd graphene layer, the first graphene layer is separated by the first separator isolation with the second graphene layer, and the second graphene layer and the 3rd graphene layer are by the second separator isolation separately.
In the present invention, Graphene dielectric layer vertically embeds first medium layer and second medium interlayer.
In the present invention, the dielectric layer of Graphene is positioned at the center at two sections of parallel waveguide intervals, and the distance to the right side plane of the first carrier strip waveguide and the left side plane of the second carrier strip waveguide equates.
In the present invention, described the first graphene layer and the 3rd graphene layer can extend out from Graphene dielectric layer upper surface, connecting electrode.
In the present invention, semiconductor substrate layer, the first carrier strip waveguide, the second carrier strip waveguide material are silicon, germanium, germanium-silicon alloy, III-V family semiconductor or II-IV family semiconductor.
In the present invention, described insulating barrier, first medium layer, second medium layer and the first separator in Graphene dielectric layer, the second separator are conductor oxidate and form, and its refractive index is significantly less than the refractive index of the first carrier strip waveguide, the second carrier strip waveguide and semiconductor substrate layer.
In the present invention, described conductor oxidate is Si oxide, silicon nitrogen oxide, boron nitride or six side's boron nitrides.
Operation principle of the present invention is:
During device work, bias voltage is applied on the graphene layer between vertical embedding two waveguides, by changing the bias voltage on Graphene, changes dynamically its optical conductivity, thereby the refractive index of graphene layer and absorptivity are changed thereupon.The power coupling of directional coupler is based on this physical phenomenon of photon tunneling effect, the graphene layer that has added refractive index to change with bias voltage between two parallel waveguides, what just make that barrier height in photon tunneling effect becomes is tunable, and coupling length also changes thereupon.Thus, the Output optical power of one of them output of directional coupler can, under the modulation of bias voltage, produce variation from low to high, and the Output optical power of another output have contrary variation from high to low.
Compared with prior art, the present invention has following beneficial effect:
The present invention has high symmetry, has the phase matched of height between two waveguides, so under rational waveguide length, output can reach very high extinction ratio; Therefore utilize the devices such as light intensity modulator that this character makes and optical switch to have at a high speed, broadband, low-power consumption, the feature that volume is little, and can be compatible mutually with CMOS technique, thereby the potentiality that have a wide range of applications.
Accompanying drawing explanation
Fig. 1 is the fundamental diagram of existing directional coupler;
Fig. 2 is the active area schematic diagram of the directional coupler based on Graphene provided by the invention;
Fig. 3 is the waveguide cross-section schematic diagram of the directional coupler based on Graphene provided by the invention;
Fig. 4 is symmetric mode and the asymmetric mould mould field distribution schematic diagram in the embodiment of the present invention;
Fig. 5 is the schematic diagram that symmetric mode in the embodiment of the present invention and asymmetric mode propagation constant, waveguide-coupled length change with bias voltage;
Fig. 6 is the power profile that in the embodiment of the present invention, waveguiding structure is overlooked;
Reference numeral is: 11 is that the first carrier strip waveguide, 12 is that first medium layer, 13 is that Graphene dielectric layer, 131 is that the first graphene layer, 132 is that the first separator, 133 is that the second graphene layer, 134 is that the second separator, 135 is that the 3rd graphene layer, 14 is that second medium layer, 15 is that the second carrier strip waveguide, 16 is that insulating barrier, 17 is semiconductor substrate layer.
Embodiment
Below in conjunction with the drawings and the specific embodiments, the invention will be further described.
A kind of directional coupler based on Graphene, comprise the first carrier strip waveguide 11, the second carrier strip waveguide 15, insulating barrier 16, semiconductor substrate layer 17, insulating barrier 16 is positioned at the upper surface of semiconductor substrate layer 17, described the first carrier strip waveguide 11 and the second carrier strip waveguide 15 are parallel to each other and are all positioned on common insulating barrier 16, between the first carrier strip waveguide 11 and the second carrier strip waveguide 15, are from left to right filled with successively first medium layer 12, Graphene dielectric layer 13 and second medium layer 14; Described Graphene dielectric layer 13 at least consists of three layers of graphene layer being parallel to each other, and described graphene layer is overlapping in whole or in part; Described Graphene dielectric layer 13 mainly consists of the first graphene layer 131, the first separator, the second graphene layer 133, the second separator 134 and the 3rd graphene layer 135, the first graphene layer 131 is separated by the first separator 132 isolation with the second graphene layer 133, and the second graphene layer 133 and the 3rd graphene layer 135 are by the second separator 134 isolation separately.
Embodiment
As shown in Figure 2 and Figure 3, it is the light wave of 1.55 μ m that the present embodiment adopts wavelength, and semiconductor substrate layer 17, the first carrier strip waveguides and the second carrier strip waveguide form (refractive index 3.47) by silicon (Si) material; First, second carrier strip duct width is 0.4 μ m, and thickness is 0.24 μ m; Insulating barrier 16, first medium layer and second medium layer, the first separator and the second separator form (refractive index 1.44) by silicon dioxide (SiO2); The first carrier strip waveguide right side plane and the second carrier strip waveguide left side interplanar spacing, the overall width of first medium layer, second medium layer, Graphene dielectric layer is 0.1 μ m, graphene layer thickness 0.7nm wherein, adjacent two Graphene spacing 7nm.First medium layer between the first carrier strip waveguide, the second carrier strip waveguide, be that Graphene dielectric layer, second medium layer and carrier strip waveguide are contour; Graphene dielectric layer is vertically embedded in the centre position between two parallel waveguide side planes, and comprising graphene layer also symmetrical along two parallel waveguide side plane centers, graphene layer is placed on this center.The first graphene layer, the 3rd graphene layer extend out connecting electrode from top.
Fig. 4 is in the embodiment of the present invention, and in the directional couple waveguide that the emulation of employing COMSOL Multiphysics software simulation obtains, symmetric mode (even supermode) and the asymmetric mould (odd supermode) of TE mould are the mould field pattern under 0.4eV at bias voltage.
Fig. 5 is in the embodiment of the present invention, the propagation constant of the symmetric mode of TE mould in directional couple waveguide (even supermode) and asymmetric mould (odd supermode), and the coupling length of directional couple waveguide is with the schematic diagram of bias voltage variation.Between symmetric mode (even supermode), asymmetric mould (odd supermode) and coupling length, should obey relation: L=π/(β even-β odd).Can see, at bias voltage 0.5eV, within the scope of 0.53eV, coupling length has maximum variation, therefore operating voltage is controlled to 0.5eV between 0.53eV.
Fig. 6 is in the embodiment of the present invention 1, and the power distribution schematic diagram that utilizes directional couple waveguide that the method for effective refractive index obtains to overlook, has shown the power coupling situation in the present embodiment.Coupling length shown in figure is 6 μ m.In conjunction with Fig. 4, Fig. 5, take upper port in the situation of input port, output port, take 0.5eV as "Off" state, 0.53eV is "On" state, waveguide length is that under 70.68 μ m, extinction ratio reaches 24dB.
Above content only describes in detail for some of the present invention being carried out in conjunction with concrete scheme, can not assert that the concrete enforcement of invention is only limited to these explanations.Concerning general technical staff of the technical field of the invention, not departing under design prerequisite of the present invention, can also make simple deduction and replacement, all should be considered as in protection scope of the present invention.
Claims (8)
1. the directional coupler based on Graphene, comprise the first carrier strip waveguide (11), the second carrier strip waveguide (15), insulating barrier (16), semiconductor substrate layer (17), insulating barrier (16) is positioned at the upper surface of semiconductor substrate layer (17), it is characterized in that, described the first carrier strip waveguide (11) is parallel to each other and is all positioned on common insulating barrier (16) with the second carrier strip waveguide (15), between the first carrier strip waveguide (11) and the second carrier strip waveguide (15), be from left to right filled with successively first medium layer (12), Graphene dielectric layer (13) and second medium layer (14), described Graphene dielectric layer (13) at least consists of three layers of graphene layer being parallel to each other, and described graphene layer is overlapping in whole or in part.
2. the directional coupler based on Graphene according to claim 1, it is characterized in that, described Graphene dielectric layer (13) mainly consists of the first graphene layer (131), the first separator, the second graphene layer (133), the second separator (134) and the 3rd graphene layer (135), the first graphene layer (131) is separated by the first separator (132) isolation with the second graphene layer (133), and the second graphene layer and the 3rd graphene layer (135) are by the second separator (134) isolation separately.
3. the directional coupler based on Graphene according to claim 1, is characterized in that, Graphene dielectric layer (13) vertically embeds between first medium layer (12) and second medium layer (14).
4. the directional coupler based on Graphene according to claim 1, it is characterized in that, the dielectric layer of Graphene (13) is positioned at the center at two sections of parallel waveguide intervals, and the distance to the right side plane of the first carrier strip waveguide (11) and the left side plane of the second carrier strip waveguide (15) equates.
5. the directional coupler based on Graphene according to claim 1, is characterized in that, described the first graphene layer (131) and the 3rd graphene layer (135) are from the Graphene dielectric layer upper surface connecting electrode that extends out.
6. according to the directional coupler based on Graphene claimed in claim 1, it is characterized in that, semiconductor substrate layer (17), the first carrier strip waveguide (11), the second carrier strip waveguide (15) material are silicon, germanium, germanium-silicon alloy, III-V family semiconductor or II-IV family semiconductor.
7. according to a kind of directional coupler based on Graphene claimed in claim 1, it is characterized in that, described insulating barrier (16), first medium layer (12), second medium layer (14) and the first separator (132) in Graphene dielectric layer (13), the second separator (134) are conductor oxidate and form, and its refractive index is significantly less than the refractive index of the first carrier strip waveguide (11), the second carrier strip waveguide (15) and semiconductor substrate layer (17).
8. according to the directional coupler based on Graphene claimed in claim 7, it is characterized in that, described conductor oxidate is Si oxide, silicon nitrogen oxide, boron nitride or six side's boron nitrides.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108287417A (en) * | 2017-12-29 | 2018-07-17 | 北京大学 | A kind of wide spectrum optical power splitter and power distribution method |
| WO2019029127A1 (en) * | 2017-08-09 | 2019-02-14 | 深圳市景程信息科技有限公司 | Graphene-based coupler with adjustable power distribution ratio |
| WO2019237250A1 (en) * | 2018-06-12 | 2019-12-19 | 东莞理工学院 | Dynamically adjustable communication function device |
| CN110727048A (en) * | 2019-11-01 | 2020-01-24 | 电子科技大学 | Graphene surface plasmon polariton-based tunable power coupler facing 2um waveband |
| CN112005432A (en) * | 2018-04-25 | 2020-11-27 | 株式会社村田制作所 | Directional coupler and directional coupler module |
| CN112904483A (en) * | 2021-01-18 | 2021-06-04 | 联合微电子中心有限责任公司 | Optical waveguide directional coupler and forming method thereof, optical network and control method thereof |
| CN113544920A (en) * | 2019-03-06 | 2021-10-22 | 思科技术公司 | Super-mode filtering waveguide transmitter |
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| GB1324577A (en) * | 1970-02-14 | 1973-07-25 | Philips Electronic Associated | Directional coupler |
| JPS62202604A (en) * | 1986-03-03 | 1987-09-07 | Nippon Telegr & Teleph Corp <Ntt> | Waveguide type directional coupler |
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2014
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Patent Citations (2)
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|---|---|---|---|---|
| GB1324577A (en) * | 1970-02-14 | 1973-07-25 | Philips Electronic Associated | Directional coupler |
| JPS62202604A (en) * | 1986-03-03 | 1987-09-07 | Nippon Telegr & Teleph Corp <Ntt> | Waveguide type directional coupler |
Non-Patent Citations (1)
| Title |
|---|
| ANDREA LOCATELLI等: ""Graphene-based electro-optical control of the beat length of dielectric couplers"", 《OPTICS COMMUNICATIONS》 * |
Cited By (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2019029127A1 (en) * | 2017-08-09 | 2019-02-14 | 深圳市景程信息科技有限公司 | Graphene-based coupler with adjustable power distribution ratio |
| CN108287417A (en) * | 2017-12-29 | 2018-07-17 | 北京大学 | A kind of wide spectrum optical power splitter and power distribution method |
| CN112005432A (en) * | 2018-04-25 | 2020-11-27 | 株式会社村田制作所 | Directional coupler and directional coupler module |
| CN112005432B (en) * | 2018-04-25 | 2022-05-27 | 株式会社村田制作所 | Directional coupler and directional coupler module |
| WO2019237250A1 (en) * | 2018-06-12 | 2019-12-19 | 东莞理工学院 | Dynamically adjustable communication function device |
| CN113544920A (en) * | 2019-03-06 | 2021-10-22 | 思科技术公司 | Super-mode filtering waveguide transmitter |
| US11888290B2 (en) | 2019-03-06 | 2024-01-30 | Cisco Technology, Inc. | Supermode filtering waveguide emitters |
| CN113544920B (en) * | 2019-03-06 | 2024-03-26 | 思科技术公司 | Ultra-mode filter waveguide transmitter |
| CN110727048A (en) * | 2019-11-01 | 2020-01-24 | 电子科技大学 | Graphene surface plasmon polariton-based tunable power coupler facing 2um waveband |
| CN110727048B (en) * | 2019-11-01 | 2020-11-24 | 电子科技大学 | Graphene surface plasmon polariton-based tunable power coupler facing 2um waveband |
| CN112904483A (en) * | 2021-01-18 | 2021-06-04 | 联合微电子中心有限责任公司 | Optical waveguide directional coupler and forming method thereof, optical network and control method thereof |
| CN112904483B (en) * | 2021-01-18 | 2022-11-04 | 联合微电子中心有限责任公司 | Optical waveguide directional coupler and forming method thereof, optical network and control method thereof |
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