CN211426972U - Distributed optical phase modulator - Google Patents
Distributed optical phase modulator Download PDFInfo
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- CN211426972U CN211426972U CN201922115541.XU CN201922115541U CN211426972U CN 211426972 U CN211426972 U CN 211426972U CN 201922115541 U CN201922115541 U CN 201922115541U CN 211426972 U CN211426972 U CN 211426972U
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Abstract
The application discloses distributed optical phase modulator includes: a substrate, and an optical waveguide disposed on the substrate; the driving electrode is arranged on the substrate and comprises a plurality of sub driving electrodes which are arranged at intervals, and a plurality of shielding electrodes which are respectively arranged among the plurality of sub driving electrodes; the optical waveguide sequentially passes through the sub driving electrodes and the plurality of shielding electrodes. The length of the drive electrode of each section is much smaller than the total length of the equivalent conventional modulator, and the drive signal voltage of each section is also much smaller than that of the equivalent conventional modulator. In the driving electrode of each part, the propagation of the optical signal can be approximately synchronous with the propagation of the electric signal, even the propagation of the electric signal can be synchronous. The walk-off phenomenon between photoelectric signals is minimized, and the upper limit of the modulation bandwidth is improved. And the shielding electrodes are respectively arranged between the sub driving electrodes, so that the crosstalk between the sub driving electrodes can be shielded, and the crosstalk between the sub driving electrodes can be greatly reduced.
Description
Technical Field
The application relates to the technical field of optical modulation, in particular to a distributed optical phase modulator.
Background
High-speed electro-optical modulation has a very wide and important application such as optical communication, microwave optoelectronics, laser beam deflection, wavefront modulation, and the like. The electro-optical modulator is a modulator made using the electro-optical effect of some electro-optical crystals, such as lithium niobate crystal (LiNb03), gallium arsenide crystal (GaAs), and lithium tantalate crystal (LiTa 03). The electro-optic effect, i.e., when a voltage is applied to the electro-optic crystal, the refractive index of the electro-optic crystal changes, resulting in a change in the characteristics of the light wave passing through the crystal, which effects modulation of the phase, amplitude, intensity, and polarization state of the optical signal.
However, in modulating light, it is difficult to achieve both low driving voltage and high modulation bandwidth modulation.
SUMMERY OF THE UTILITY MODEL
It is a primary object of the present application to provide a distributed optical phase modulator to achieve modulation with low drive voltage and high modulation bandwidth.
Based on this, the embodiment of the present application provides a distributed optical phase modulator, including: a substrate, and an optical waveguide disposed on the substrate; the driving electrode is arranged on the substrate and comprises a plurality of sub driving electrodes which are arranged at intervals, and a plurality of shielding electrodes which are respectively arranged among the plurality of sub driving electrodes; the optical waveguide sequentially passes through the sub driving electrodes and the plurality of shielding electrodes.
Optionally, the drive electrode is a coplanar waveguide structure.
Optionally, the same electrical signal is applied to the sub-driving electrodes.
Optionally, the electrical signal applied to the adjacent sub-driving electrodes has a time delay, wherein the time duration of the time delay is the time duration required for the optical signal to be transmitted from the starting end of the previous sub-driving electrode to the starting end of the adjacent next sub-driving electrode.
Optionally, the optical waveguide includes a plurality of modulation portions and a plurality of bending portions connected between the modulation portions, wherein a bending direction of the bending portion is toward a previous modulation portion connected to the bending portion.
Optionally, the modulation unit includes a first sub-modulation unit and a second sub-modulation unit, wherein light propagation directions inside the first sub-modulation unit and the second sub-modulation unit are opposite.
Optionally, the first sub-modulation section is parallel to the second sub-modulation section, and propagation directions of optical signals in the first sub-modulation section and the second sub-modulation section are opposite.
Optionally, the first sub-modulation part penetrates the sub-driving electrode; the second sub-modulation section passes through the shield electrode.
Optionally, the sub driving electrodes include: a signal electrode located at one side of the optical waveguide and applied with a driving signal; and a ground electrode positioned at the other side of the optical waveguide.
Optionally, the shielding electrode comprises: the first grounding wire is positioned on one side of the optical waveguide, and the second grounding wire is positioned on the other side of the optical waveguide.
The application has the following beneficial effects:
the driving electrodes are distributed, and the length of the driving electrode of each part is far smaller than the total length of the equivalent traditional modulator, and the driving signal voltage of each part is also far smaller than that of the equivalent traditional modulator. In the driving electrode of each part, the propagation of the optical signal can be approximately synchronous with the propagation of the electric signal, even the propagation of the electric signal can be synchronous. The walk-off phenomenon between photoelectric signals is minimized, and the upper limit of the modulation bandwidth is improved. Meanwhile, as the driving electrodes are changed from the traditional one-section driving electrodes into the distributed multi-section driving electrodes, the driving voltage required to be applied to each electrode is greatly reduced. And the shielding electrodes are respectively arranged between the sub driving electrodes, so that the crosstalk between the sub driving electrodes can be shielded, and the crosstalk between the sub driving electrodes can be greatly reduced.
The electric signals applied to the sub-driving electrodes are the same, the same electric signals are applied to the driving electrodes of each part, and the electric signals are reset when the electric signals are transmitted along the driving electrodes of each part, so that the loss of the electric signals is greatly reduced, and the modulation efficiency is greatly improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, serve to provide a further understanding of the application and to enable other features, objects, and advantages of the application to be more apparent. The drawings and their description illustrate the embodiments of the invention and do not limit it. In the drawings:
FIG. 1 is a schematic diagram of a distributed optical phase modulator according to an embodiment of the present application;
fig. 2 is a schematic partial cross-sectional view of a distributed optical phase modulator according to an embodiment of the present application.
Detailed Description
In order to make the technical solutions better understood by those skilled in the art, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only partial embodiments of the present application, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusions
It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.
As described in the background, there is often a trade-off between drive voltage and modulation bandwidth. The electro-optic effect is typically weak in the electro-optic medium, so low modulation voltages require a sufficiently long waveguide to cumulatively produce a sufficient electro-optic effect. However, the applicant finds that there is a group velocity mismatch between the optical wave and the driving electrical signal, and a severe wave-off phenomenon occurs when the optical wave and the driving electrical signal are transmitted over a long distance, which severely limits the modulation bandwidth. In addition, the long optical waveguide also requires a long driving electrode, which results in a large microwave driving signal propagation loss due to the resistive loss of the electrode material, and ultimately limits the possibility of further lowering the driving voltage. And, at the same time, as the modulation bandwidth increases, the problem of crosstalk between multiple signals becomes more and more significant. Eventually, it is difficult to further reduce the driving voltage. This serious design tradeoff problem exists for almost all traveling wave based electro-optic modulators, severely limiting device performance.
Based on the research findings of the applicant, the embodiments of the present invention provide a distributed optical phase modulator, as shown in fig. 1, including: a substrate 10, and an optical waveguide 20 disposed on the substrate 10; a driving electrode 30 disposed on the substrate 10 and including a plurality of sub-driving electrodes 31 arranged at intervals, and a plurality of shielding electrodes 40 respectively disposed between the plurality of sub-driving electrodes 31; the optical waveguide 20 sequentially passes through the sub-driving electrode 31 and the plurality of shielding electrodes 40, and due to the group velocity mismatch between the optical wave and the driving electrical signal, a serious optical wave-driving point signal walk-off phenomenon is generated through long-distance transmission, which severely limits the reduction of the driving voltage and the improvement of the modulation bandwidth. Therefore, in the present embodiment, the driving electrodes 30 are distributed driving electrodes, and since the driving electrodes 30 are distributed, the length of the driving electrode 30 in each portion is much smaller than the total length of the modulator, and in the driving electrode 30 in each portion, the propagation of the optical signal and the propagation of the electrical signal can be approximately synchronized, even synchronized. The walk-off phenomenon between the photoelectric signals is minimized, and the upper limit of the modulation bandwidth at a higher level is improved. Since the problem of crosstalk between multiple signals becomes more and more significant as the bandwidth increases, the plurality of shielding electrodes 40 are respectively disposed between the plurality of sub driving electrodes 31 to shield the crosstalk between the sub driving electrodes 31, so that the crosstalk between the sub driving electrodes can be greatly reduced. The drive voltage is further reduced while increasing the bandwidth.
As exemplary embodiments, the optical modulator may be a lithium niobate crystal (LiNb03) optical modulator, a gallium arsenide crystal (GaAs) optical modulator, or a lithium tantalate crystal (LiTa03) optical modulator. In this embodiment, a lithium niobate crystal optical modulator will be described as an example. As shown in fig. 2, the optical waveguide 20 and the driving electrode 30 are located on the surface of the substrate 10, and a bonding layer 50 may be further disposed between the substrate 10 and the optical waveguide 20 and the driving electrode 30.
As an exemplary embodiment, the driving electrode 30 includes a signal electrode S to which an electric signal is applied and a ground electrode G. The optical waveguide is located between the signal electrode S and the ground electrode G. In the present embodiment, the signal electrode S and the ground electrode G of the driving electrode may be disposed in parallel with the optical waveguide. In this embodiment, the optical waveguide is made of an electro-optical material, the refractive index of which varies with the magnitude of an applied voltage, and the accumulated phase of input light passing through the optical waveguide varies with the voltage applied to the optical waveguide. Optical phase modulation is achieved by applying an electrical signal across the drive electrodes to change the phase of the optical signal in the optical waveguide.
As an exemplary embodiment, the driving electrode 30 includes N sub driving electrodes 31 arranged at intervals along the optical waveguide 20, where N ≧ 2. As shown in fig. 1. The drive electrode 30 is divided into N sections, each section having a shorter length L, the final effective drive length being N x L. In the present embodiment, the electrical signals applied to the sub-driving electrodes 31 are the same, and the same electrical signals are applied to each part of the sub-driving electrodes 31, which is equivalent to resetting the electrical signals when the electrical signals propagate along each part of the sub-driving electrodes 31, so that the loss of the electrical signals is greatly reduced, and the modulation efficiency is greatly improved.
In order to better match the electrical signals on the sub-driving electrodes 31, so that the modulation of the optical signal on each sub-driving electrode 31 is as same as possible, in the present embodiment, the electrical signals applied on adjacent sub-driving electrodes 31 have a delay, wherein the duration of the delay is the duration required for the optical signal to be transmitted from the end of the previous sub-driving electrode 31 to the start of the adjacent next sub-driving electrode 31. As an exemplary embodiment, it is assumed that the electric signal applied to the first sub-driving electrode 31 is V1(t), the time required for the optical signal to travel from the end of the nth sub-driving electrode 31 to the start of the (n + 1) th sub-driving electrode 31 isnWherein N-1, 2, …, N-1 representsWhich is the fourth sub-drive electrode 31. The expression of the electric signal applied to each sub-drive electrode 31 is as follows:
due to the delay of the electrical signal and the optical signal applied to the adjacent sub-driving electrodes 31 before the distributed driving electrode 30, the sub-driving electrodes 31 of each part have the same electrical signal, which is equivalent to resetting the electrical signal when the electrical signal propagates along each part of the sub-driving electrodes 31, so that the loss of the electrical signal is greatly reduced, and the modulation efficiency is greatly improved.
In the present embodiment, the driving electrode 30 is a coplanar waveguide structure, which may be exemplified by a GS coplanar waveguide line (other phase modulation units may also be used in the coplanar waveguide structure). The unmodulated constant-brightness light source passes through the N sub-drive electrode 31 regions in sequence from the entrance end input. The sub-driving electrode 31 has a left end which is an input region of an electrical signal and a right end which is coupled to an external microwave termination isolator (RF terminator) or an on-chip circuit. The input optical signal is output after passing through the multi-segment sub-driving electrodes 31. As an exemplary embodiment, the impedance of the sub driving electrode 31 is the same as or similar to the impedance of the electric signal input terminal, for example, may be 50 Ω; the propagation speed of the electrical signal in the driving electrode 30 is the same as or similar to the speed of light in the optical waveguide 20; the resistance loss of the electric signal transmitted in the driving electrode 30 is as low as possible, and in this embodiment, the driving electrode 30 may be made of a high-conductivity low-resistance material such as gold, silver, graphene, or the like.
As an exemplary embodiment, as shown in fig. 1, the optical waveguide includes a plurality of modulation parts 21 and a plurality of bending parts 22 connected between the modulation parts 21, wherein a bending direction of the bending part 22 is toward a previous modulation part 21 connected to the bending part 22. Illustratively, the optical waveguide starts from the first modulation section 21, the bending direction of the first bending portion 22 connected to the first modulation section 21 is toward the first modulation section 21, so that the extending direction of the second modulation section 21 connected to the first bending portion 22 is toward the first modulation section 21, and the plurality of modulation sections 21 are connected to the plurality of bending portions 22 to form a shape of a substantially "S" shape or a "serpentine shape" extending back and forth. As an exemplary embodiment, the modulation section 21 includes a first sub-modulation section and a second sub-modulation section, wherein light propagation directions inside the first sub-modulation section and the second sub-modulation section are different. For example, the extending direction of the first sub-modulation part may be a "forward" direction of the optical waveguide, and the extending direction of the second sub-modulation part may be a "backward" direction of the optical waveguide.
As an exemplary embodiment, the first sub-modulation section passes through the sub-driving electrode, and the second sub-modulation section passes through the shielding electrode, for example, as shown in fig. 1, the first sub-modulation section and the second sub-modulation section are disposed at intervals along the Y direction of the substrate surface, and the sub-driving electrode is disposed at intervals from the shielding electrode. The signal electrode is positioned on one side of the first sub-modulation part, the grounding electrode is positioned on the other side of the first sub-modulation part, meanwhile, the first grounding wire G1 of the shielding electrode is positioned on one side of the second sub-modulation part, and the second grounding wire G2 of the shielding electrode is positioned on the other side of the second sub-modulation part.
The above description is only a preferred embodiment of the present application and is not intended to limit the present application, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, improvement and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.
Claims (10)
1. A distributed optical phase modulator, comprising:
a substrate, and an optical waveguide disposed on the substrate;
a driving electrode disposed on the substrate and including a plurality of sub-driving electrodes arranged at intervals,
a plurality of shield electrodes respectively disposed between the plurality of sub-drive electrodes;
the optical waveguide sequentially passes through the sub driving electrodes and the plurality of shielding electrodes.
2. The distributed optical phase modulator of claim 1,
the driving electrode is a coplanar waveguide structure.
3. The distributed optical phase modulator of claim 2,
the same electrical signal is applied to the sub-driving electrodes.
4. The distributed optical phase modulator of claim 3,
the electrical signals applied to the adjacent sub-driving electrodes have time delays, wherein the time duration of the time delay is the time duration required for the optical signals to be transmitted from the starting end of the previous sub-driving electrode to the starting end of the adjacent next sub-driving electrode.
5. The distributed optical phase modulator of any of claims 1-4 wherein the optical waveguide comprises a plurality of modulating portions and a plurality of curved portions connected between the modulating portions, wherein a direction of curvature of the curved portions is toward a last modulating portion connected to the curved portions.
6. The distributed optical phase modulator of claim 5 wherein the modulating section comprises a first sub-modulating section and a second sub-modulating section, wherein the directions of light propagation within the first sub-modulating section and the second sub-modulating section are opposite.
7. The distributed optical phase modulator of claim 6,
the first sub-modulation part is parallel to the second sub-modulation part, and the propagation directions of optical signals in the first sub-modulation part and the second sub-modulation part are opposite.
8. The distributed optical phase modulator of claim 6 or 7,
the first sub-modulation part penetrates through the sub-driving electrode;
the second sub-modulation section passes through the shield electrode.
9. The distributed optical phase modulator of claim 1 wherein said sub-drive electrodes comprise:
a signal electrode located at one side of the optical waveguide and applied with a driving signal; and a ground electrode positioned at the other side of the optical waveguide.
10. The distributed optical phase modulator of claim 1 wherein said shield electrode comprises:
the first grounding wire is positioned on one side of the optical waveguide, and the second grounding wire is positioned on the other side of the optical waveguide.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201922115541.XU CN211426972U (en) | 2019-11-29 | 2019-11-29 | Distributed optical phase modulator |
| US17/639,345 US12025865B2 (en) | 2019-11-29 | 2020-03-30 | Distributed optical phase modulator |
| PCT/CN2020/081992 WO2021103367A1 (en) | 2019-11-29 | 2020-03-30 | Distributed optical phase modulator |
| EP20892864.8A EP4006629A4 (en) | 2019-11-29 | 2020-03-30 | Distributed optical phase modulator |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201922115541.XU CN211426972U (en) | 2019-11-29 | 2019-11-29 | Distributed optical phase modulator |
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| CN211426972U true CN211426972U (en) | 2020-09-04 |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110737115A (en) * | 2019-11-29 | 2020-01-31 | 苏州极刻光核科技有限公司 | Distributed optical phase modulator |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN110737115A (en) * | 2019-11-29 | 2020-01-31 | 苏州极刻光核科技有限公司 | Distributed optical phase modulator |
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