CN110989215B - Differential lithium niobate modulator - Google Patents
Differential lithium niobate modulator Download PDFInfo
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- CN110989215B CN110989215B CN201911344423.4A CN201911344423A CN110989215B CN 110989215 B CN110989215 B CN 110989215B CN 201911344423 A CN201911344423 A CN 201911344423A CN 110989215 B CN110989215 B CN 110989215B
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/0305—Constructional arrangements
- G02F1/0316—Electrodes
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/0327—Operation of the cell; Circuit arrangements
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- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/03—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect
- G02F1/035—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on ceramics or electro-optical crystals, e.g. exhibiting Pockels effect or Kerr effect in an optical waveguide structure
Abstract
The invention discloses a differential lithium niobate modulator, which relates to the technical field of optical communication devices and comprises a substrate layer, an integrated waveguide layer and a covering layer from bottom to top in sequence, wherein the integrated waveguide layer comprises a lithium niobate waveguide layer and two high-refractive-index layers which are distributed at intervals and are positioned between the lithium niobate waveguide layer and the covering layer; meanwhile, the modulator also comprises a first electrode group and two oppositely arranged second electrode groups, wherein the first electrode group is positioned in the substrate layer, and the two second electrode groups are positioned above the integrated waveguide layer; the first electrode group sequentially comprises a first metal electrode and a first conducting layer which are in direct contact from bottom to top; the second electrode group sequentially comprises a second conducting layer and a second metal electrode which are in direct contact from bottom to top. The differential lithium niobate modulator provided by the invention has the advantages of strong anti-interference capability, small structural size, high adjusting efficiency and the like.
Description
Technical Field
The invention relates to the technical field of optical communication devices, in particular to a differential lithium niobate modulator.
Background
Because the lithium niobate material has excellent performance, has the advantages of high electro-optic response, high intrinsic bandwidth, wide transparent window (0.35-5 um), good thermal stability and the like, the lithium niobate material has been widely researched and applied in electro-optic modulators. Particularly, with the rapid development of thin-film lithium niobate in recent years, the problem of etching of lithium niobate waveguides is solved, and thin-film lithium niobate modulators are widely researched. Compared with the traditional lithium niobate modulator, the thin-film lithium niobate modulator has the advantages of high modulation bandwidth, small structural size, high adjustment efficiency and the like.
In the prior art, due to the characteristics of lithium niobate materials, a high-speed lithium niobate modulator is generally designed based on a single-ended structure, but the modulator with the single-ended structure has low interference rejection and is easily influenced by external noise, so that the performance of the modulator is reduced. On the other hand, due to the limitation of the output voltage of the driver, the modulation depth of the single-ended structure modulator is relatively low, so that the output voltage of the driver needs to be increased or the structure size of the modulator needs to be increased, which results in the reduction of the performance of the modulator and the increase of the cost.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to provide a differential lithium niobate modulator which has the advantages of strong anti-interference capability, small structural size, high regulation efficiency and the like.
In order to achieve the above purposes, the technical scheme adopted by the invention is as follows:
a differential lithium niobate modulator comprises a substrate layer, an integrated waveguide layer and a covering layer from bottom to top in sequence, wherein the integrated waveguide layer comprises a lithium niobate waveguide layer and two high-refractive-index layers distributed at intervals, and the high-refractive-index layers are positioned between the lithium niobate waveguide layer and the covering layer; at the same time, the user can select the desired position,
the modulator further comprises a first electrode set, two oppositely arranged second electrode sets, the first electrode set is positioned in the substrate layer and above the two integrated waveguide layers;
the first electrode group sequentially comprises a first metal electrode and a first conducting layer which are in direct contact from bottom to top, and the projections of the two high-refractive-index layers are located on the first conducting layer;
the second electrode group sequentially comprises a second conducting layer and a second metal electrode which are in direct contact from bottom to top, and the second conducting layer is correspondingly distributed right above one high-refractive-index layer.
On the basis of the technical scheme, the substrate layer is made of a low-refractive-index material, and the thickness of the substrate layer is not less than 2 um.
On the basis of the technical scheme, the thickness of the first conductive layer and the second conductive layer is not more than 50 nm.
On the basis of the technical scheme, the thickness of the lithium niobate waveguide layer is not more than 1 um.
On the basis of the technical scheme, the refractive index of the high-refractive-index layer is not less than 1.8.
On the basis of the technical scheme, the heights of the first metal electrode and the second metal electrode are not less than 500 nm.
On the basis of the technical scheme, the widths of the first metal electrode and the second metal electrode are not less than 10 um.
On the basis of the technical scheme, the refractive index of the covering layer is not more than 1.8.
On the basis of the above technical solution, the first conductive layer is directly attached to the lithium niobate waveguide layer, and the second conductive layer is directly attached to the high refractive index layer.
On the basis of the technical scheme, isolation layers are arranged between the first conducting layer and the lithium niobate waveguide layer and between the second conducting layer and the high-refractive-index layer, and the isolation layers are made of low-refractive-index materials.
Compared with the prior art, the invention has the advantages that: the differential lithium niobate modulator provided by the invention can support differential signal driving, not only can improve the modulation depth of the modulator, but also has stronger signal anti-interference capability and is not easily influenced by external noise; meanwhile, the electrode group comprises a metal electrode and a conducting layer, and the conducting layer can greatly shorten the distance between the electrode and the integrated waveguide and improve the modulation efficiency of modulation.
Drawings
Fig. 1 is a schematic structural diagram of a differential lithium niobate modulator in a first embodiment of the present invention;
fig. 2 is a schematic structural diagram of a differential lithium niobate modulator according to a second embodiment of the present invention.
In the figure: 1-a substrate layer, 2-a substrate layer, 3-an integrated waveguide layer, 301-a lithium niobate waveguide layer, 302-a high refractive index layer, 4-a cladding layer, 5-a first electrode group, 501-a first metal electrode, 502-a first conductive layer, 6-a second electrode group, 601-a second conductive layer, 602-a second metal electrode.
Detailed Description
The technical solutions of the embodiments of the present invention will be described clearly and completely with reference to the accompanying drawings, and it is to be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present invention, it should be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. It is to be noted that all the figures are exemplary representations. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
The invention is described in further detail below by means of specific embodiments and with reference to the attached drawings.
Example one
Referring to fig. 1, the differential lithium niobate modulator provided in the embodiment of the present invention sequentially includes, from bottom to top, a substrate layer 1, a substrate layer 2, an integrated waveguide layer 3, and a cover layer 4, where the integrated waveguide layer 3 includes a lithium niobate waveguide layer 301 and two high refractive index layers 302 distributed at intervals, and the high refractive index layer 302 is located between the lithium niobate waveguide layer 301 and the cover layer 4; at the same time, the user can select the desired position,
the modulator further comprises a first set of electrodes 5, two oppositely arranged second sets of electrodes 6, the first set of electrodes 5 being located within the substrate layer 2 and the two second sets of electrodes 6 being located above the integrated waveguide layer (3);
the first electrode group 5 sequentially comprises a first metal electrode 501 and a first conductive layer 502 which are in direct contact from bottom to top, and the projections of the two high refractive index layers 302 are both located on the first conductive layer 502;
the second electrode group 6 sequentially includes a second conductive layer 601 and a second metal electrode 602, which are in direct contact with each other, from bottom to top, and the second conductive layers 601 are correspondingly distributed right above one high refractive index layer 302.
Still further, in the embodiment of the present invention, the substrate layer 2 is a low refractive index material, and the thickness of the substrate layer 2 is not less than 2 um. The substrate layer 2 has a refractive index of between 1 and 1.8 and is transparent in the operating wavelength range, and the material of the substrate layer 2 may be, but is not limited to, silicon dioxide and silicon oxynitride.
Further, in the embodiment of the present invention, the thickness of the first conductive layer 502 and the second conductive layer 601 does not exceed 50 nm. The material of the first conductive layer 502 and the second conductive layer 601 can be, but is not limited to, doped silicon, graphene, germanium, iii-v materials, and indium tin oxide.
Further, in the embodiment of the present invention, the thickness of the lithium niobate waveguide layer 301 is not more than 1um, and the tangential direction of the lithium niobate waveguide layer 301 is Z-cut.
Further, in the embodiment of the present invention, the refractive index of the high refractive index layer 302 is not less than 1.8, and the high refractive index layer 302 is a transparent material, and the material of the high refractive index layer 302 may be, but is not limited to, silicon nitride, and silicon oxynitride. The thickness of high refractive index layer 302 is not more than 1um, and the width is not more than 4um, and the interval between two high refractive index layers 302 is greater than evanescent wave coupling's distance, can effectively prevent the light wave mutual interference in two high refractive index layers 302.
Further, in the embodiment of the present invention, the height of the first metal electrode 501 and the second metal electrode 602 is not less than 500nm, and the width of the first metal electrode 501 and the second metal electrode 602 is not less than 10um, and the material of the first metal electrode 501 and the second metal electrode 602 may be, but not limited to, gold, silver, copper, and aluminum.
Still further, in the embodiment of the present invention, the refractive index of the covering layer 4 is not greater than 1.8, and the material of the covering layer 4 may be, but is not limited to, silicon oxide, silicon oxynitride, or a polymer material.
Further, in the embodiment of the present invention, the thickness of the first conductive layer 502 and the second conductive layer 601 is not more than 1um, and the first conductive layer 502 is directly attached to the lithium niobate waveguide layer 301, and the second conductive layer 601 is directly attached to the high refractive index layer 302.
Example two
The difference between the embodiment of the invention and the first embodiment is only that: isolation layers are arranged between the first conducting layer 502 and the lithium niobate waveguide layer 301 and between the second conducting layer 601 and the high-refractive-index layer 302, and the isolation layers are made of low-refractive-index materials.
The working principle of the electro-optical modulator provided by the embodiment of the invention is as follows:
the electro-optical modulator provided by the invention is a differential lithium niobate modulator, wherein a first electrode group is 'ground', and can be marked as 'G'; the two symmetrically placed second electrode sets are two signal electrodes, labeled "S1" and "S2", respectively. In operation of the differential modulator, different voltages are applied to the two signal electrodes "S1" and "S2", respectively. The lithium niobate waveguide layer 301 and the two high refractive index layers 302 in the embodiment of the present invention constitute two hybrid waveguides, and based on the electro-optical characteristics of the lithium niobate material, the phase change of the two waveguides is proportional to the voltage difference applied to the two signal electrodes "S1" and "S2". The voltage difference is determined by the signal transmitting end and cannot be influenced by some random disturbance outside the electrode, so that the anti-interference capability of the modulator is improved.
The differential lithium niobate modulator provided by the invention can support differential signal driving, not only can improve the modulation depth of the modulator, but also has stronger signal anti-interference capability and is not easily influenced by external noise; meanwhile, the electrode group comprises a metal electrode and a conducting layer, and the conducting layer can greatly shorten the distance between the electrode and the integrated waveguide and improve the modulation efficiency of modulation.
The present invention is not limited to the above-described embodiments, and it will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the principle of the present invention, and such modifications and improvements are also considered to be within the scope of the present invention. Those not described in detail in this specification are within the skill of the art.
Claims (10)
1. The differential lithium niobate modulator is characterized by sequentially comprising a substrate layer (1), a substrate layer (2), an integrated waveguide layer (3) and a covering layer (4) from bottom to top, wherein the integrated waveguide layer (3) comprises a lithium niobate waveguide layer (301) and two high-refractive-index layers (302) which are distributed at intervals, and the high-refractive-index layers (302) are positioned between the lithium niobate waveguide layer (301) and the covering layer (4); at the same time, the user can select the desired position,
the modulator further comprises a first set of electrodes (5), two oppositely arranged second sets of electrodes (6), the first set of electrodes (5) being located within the substrate layer (2), the two second sets of electrodes (6) being located above the integrated waveguide layer (3);
the first electrode group (5) sequentially comprises a first metal electrode (501) and a first conductive layer (502) which are in direct contact from bottom to top, and the projections of the two high-refractive-index layers (302) are located on the first conductive layer (502);
the second electrode group (6) sequentially comprises a second conducting layer (601) and a second metal electrode (602) which are in direct contact from bottom to top, and the second conducting layer (601) is correspondingly distributed right above the high-refractive-index layer (302).
2. The differential lithium niobate modulator of claim 1, wherein: the substrate layer (2) is a low-refractive-index material, and the thickness of the substrate layer (2) is not less than 2 um.
3. The differential lithium niobate modulator of claim 1, wherein: the thickness of the first conductive layer (502) and the second conductive layer (601) does not exceed 50 nm.
4. The differential lithium niobate modulator of claim 1, wherein: the thickness of the lithium niobate waveguide layer (301) is not more than 1 um.
5. The differential lithium niobate modulator of claim 1, wherein: the high refractive index layer (302) has a refractive index of not less than 1.8.
6. The differential lithium niobate modulator of claim 1, wherein: the height of the first metal electrode (501) and the second metal electrode (602) is not less than 500 nm.
7. The differential lithium niobate modulator of claim 1, wherein: the width of the first metal electrode (501) and the second metal electrode (602) is not less than 10 um.
8. The differential lithium niobate modulator of claim 1, wherein: the refractive index of the cover layer (4) is not more than 1.8.
9. The differential lithium niobate modulator of claim 1, wherein: the first conductive layer (502) is directly attached to the lithium niobate waveguide layer (301), and the second conductive layer (601) is directly attached to the high refractive index layer (302).
10. The differential lithium niobate modulator of claim 1, wherein: isolation layers are arranged between the first conducting layer (502) and the lithium niobate waveguide layer (301) and between the second conducting layer (601) and the high-refractive-index layer (302), and the isolation layers are made of low-refractive-index materials.
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| CN201911344423.4A CN110989215B (en) | 2019-12-23 | 2019-12-23 | Differential lithium niobate modulator |
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| CN201911344423.4A CN110989215B (en) | 2019-12-23 | 2019-12-23 | Differential lithium niobate modulator |
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| CN110989215B true CN110989215B (en) | 2022-07-01 |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1132764A1 (en) * | 2000-03-08 | 2001-09-12 | JDS Uniphase Corporation | Electro-optic modulator with enhanced temperature stability |
| TW201842381A (en) * | 2017-04-18 | 2018-12-01 | 日商日本電信電話股份有限公司 | Semiconductor mach-zehnder modulator |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7324257B2 (en) * | 2004-07-27 | 2008-01-29 | Jds Uniphase Corporation | Low bias drift modulator with buffer layer |
| US20110170820A1 (en) * | 2009-11-04 | 2011-07-14 | University Of Delaware | Eo polymer-based dual slot waveguide modulators |
| WO2016194369A1 (en) * | 2015-06-02 | 2016-12-08 | 日本電信電話株式会社 | Semiconductor optical modulation element |
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2019
- 2019-12-23 CN CN201911344423.4A patent/CN110989215B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1132764A1 (en) * | 2000-03-08 | 2001-09-12 | JDS Uniphase Corporation | Electro-optic modulator with enhanced temperature stability |
| TW201842381A (en) * | 2017-04-18 | 2018-12-01 | 日商日本電信電話股份有限公司 | Semiconductor mach-zehnder modulator |
Non-Patent Citations (1)
| Title |
|---|
| "Optically Induced Channel Waveguide Structures with Spatial Modulation of Parameters in the Surface Layer of Lithium Niobate";A.D.Bezpaly 等;《Optics and Spectroscopy》;20190711;第62卷;第387-392页 * |
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