CN112859389A - Thin-film lithium niobate electro-optical switch - Google Patents
Thin-film lithium niobate electro-optical switch Download PDFInfo
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- CN112859389A CN112859389A CN202110046813.4A CN202110046813A CN112859389A CN 112859389 A CN112859389 A CN 112859389A CN 202110046813 A CN202110046813 A CN 202110046813A CN 112859389 A CN112859389 A CN 112859389A
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- GQYHUHYESMUTHG-UHFFFAOYSA-N lithium niobate Chemical compound [Li+].[O-][Nb](=O)=O GQYHUHYESMUTHG-UHFFFAOYSA-N 0.000 title claims abstract description 89
- 239000010409 thin film Substances 0.000 title claims abstract description 87
- 230000003287 optical effect Effects 0.000 claims abstract description 127
- 229910052751 metal Inorganic materials 0.000 claims abstract description 97
- 239000002184 metal Substances 0.000 claims abstract description 97
- 238000005253 cladding Methods 0.000 claims abstract description 33
- 230000009471 action Effects 0.000 claims abstract description 7
- 239000000758 substrate Substances 0.000 claims abstract description 5
- 238000005530 etching Methods 0.000 claims description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 6
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 239000000463 material Substances 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 230000008878 coupling Effects 0.000 description 3
- 238000010168 coupling process Methods 0.000 description 3
- 238000005859 coupling reaction Methods 0.000 description 3
- 230000005693 optoelectronics Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 238000002955 isolation Methods 0.000 description 2
- 230000004044 response Effects 0.000 description 2
- 230000005699 Stark effect Effects 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 230000009022 nonlinear effect Effects 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
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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
- G02F1/0305—Constructional 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
- G02F1/0338—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 structurally associated with a photoconductive layer or having photo-refractive properties
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- Engineering & Computer Science (AREA)
- Ceramic Engineering (AREA)
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Abstract
A thin-film lithium niobate electro-optical switch comprises a substrate, a lower cladding, a thin-film lithium niobate flat optical waveguide, an electro-optical switch component and an upper cladding which are stacked from bottom to top, wherein the electro-optical switch component comprises an input coupler, an electro-optical action area and an output coupler which are sequentially arranged on the thin-film lithium niobate flat optical waveguide along an optical path, and the input coupler is provided with at least one first input optical waveguide, a first multimode interference area and two first output optical waveguides; the output coupler has two second input optical waveguides, a second multimode interference region and at least one second output optical waveguide; the electro-optical action area is provided with a ground electrode and a signal electrode; the ground electrode and the signal electrode are both composed of an upper layer metal electrode and a lower layer metal electrode which are arranged from top to bottom, and the thickness of the upper layer metal electrode is larger than that of the lower layer metal electrode. The invention can effectively reduce the driving voltage of the optical switch and simultaneously ensure that the electro-optical wave speeds can be matched.
Description
Technical Field
The invention relates to the field of integrated microwave photonic chips, in particular to a thin-film lithium niobate electro-optical switch.
Background
The optical switch is used as a key device in a microwave photonic system, has the function of realizing the switching and switching of an optical path, and has wide application prospect in a high-performance broadband phased array radar beam forming network, a multi-channel high-speed photon analog-to-digital converter and a broadband reconfigurable microwave photon signal processing system.
Currently, the types of optical switches mainly include mechanical optical switches, MEMS optical switches, thermo-optical switches, magneto-optical switches, electro-optical switches, and the like. The electro-optical switch is the only one type of current optical switch with switching speed reaching dozens ns to hundreds of ns, is mainly realized by utilizing nonlinear effects of materials, including linear electro-optical effect, quantum confinement Stark effect, plasma dispersion effect and the like, the refractive index of the materials is changed by an external electric field, the device generally has fast switching response speed, and the common electro-optical materials comprise lithium niobate crystals, III-V compounds, PLZT, Si, polymers and the like. In addition to the above electro-optical switches, in recent years, a novel electro-optical switch based on a thin-film lithium niobate material has been a research hotspot internationally, the thin-film lithium niobate electro-optical switch adopts a sub-wavelength optical waveguide to improve the limitation on an optical field, and has comprehensive advantages in the aspects of device size, switching speed, insertion loss and the like, and the lithium niobate material has the advantages of strong linear electro-optical effect, low transmission loss and good stability as a natural electro-optical crystal.
The driving voltage of the thin-film lithium niobate electro-optical switch based on the linear electro-optical effect is mainly related to two factors, namely the length of an electro-optical action area and the distance between a signal electrode and a ground electrode, and the longer the length of the electro-optical action area is, the smaller the distance between the electrodes is, and the lower the driving voltage is. However, the increase of the length of the electro-optical active region increases the overall size of the device, which is not beneficial to miniaturization of the device, and to ensure the switching speed of the optical switch, good electro-optical beam matching is required, so that the distance between the electrodes cannot be too small, which results in that the switch driving voltage is difficult to reduce under the condition of fixed length of the device. In addition, the thin-film lithium niobate device adopts a ridge type optical waveguide as a basic optical transmission structure, the ridge type optical waveguide structurally comprises a lower-layer slab waveguide and an upper-layer strip carrier, and due to the existence of a slab waveguide area, partial optical field energy can be outwards dispersed from the slab area when light is transmitted along the waveguide, so that crosstalk between adjacent optical waveguides is increased, namely, crosstalk between output ports of the electro-optical switch is increased. Therefore, new device structures and electrode structures need to be explored in device structure design to reduce crosstalk of the output port of the optical switch, enhance electro-optical interaction and reduce driving voltage.
Disclosure of Invention
In order to solve the problems, the invention provides a thin-film lithium niobate electro-optical switch.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a thin-film lithium niobate electro-optical switch comprises a substrate, a lower cladding, a thin-film lithium niobate flat optical waveguide, an electro-optical switch component and an upper cladding which are stacked from bottom to top, wherein the electro-optical switch component comprises:
an input coupler, an electro-optic active region and an output coupler arranged on the thin film lithium niobate slab optical waveguide along the optical path in sequence, wherein,
the input coupler is provided with at least one first input optical waveguide, a first multimode interference region and two first output optical waveguides, and the first input optical waveguide, the first multimode interference region and the first output optical waveguides are sequentially connected;
the output coupler is provided with two second input optical waveguides, a second multimode interference region and at least one second output optical waveguide, and the first input optical waveguide, the first multimode interference region and the first output optical waveguide are sequentially connected;
the electro-optical action region is provided with a ground electrode and a signal electrode, the ground electrode is positioned at two sides of the signal electrode, and a thin-film lithium niobate straight waveguide is arranged between the ground electrode and the signal electrode;
the ground electrode and the signal electrode are both provided with an upper layer metal electrode and a lower layer metal electrode which are arranged from top to bottom, and the thickness of the upper layer metal electrode is larger than that of the lower layer metal electrode.
Furthermore, the area of the thin film lithium niobate slab optical waveguide, which is positioned between the two first output optical waveguides, is provided with a first deep etching area; the area of the thin film lithium niobate flat optical waveguide between the two second input optical waveguides is provided with a second deep etching area.
Furthermore, the cross section of the thin-film lithium niobate straight waveguide is trapezoidal.
Furthermore, the input ends of the thin-film lithium niobate straight waveguides are respectively connected with the two first output optical waveguides, and the output ends of the thin-film lithium niobate straight waveguides are respectively connected with the second input optical waveguides.
Furthermore, the tops of the upper metal electrodes of the ground electrode and the signal electrode extend out of the upper cladding, and the upper cladding and the lower cladding are made of silicon dioxide.
Further, the thickness of the lower cladding is 1-5 μm; the thickness of the upper cladding layer is 1-3 μm.
Furthermore, the widths of the first input optical waveguide, the second input optical waveguide, the first output optical waveguide, the second output optical waveguide and the thin-film lithium niobate straight waveguide are all 500nm-2 μm, and the widths of the first multimode interference area and the second multimode interference area are 6 μm-100 μm.
Furthermore, the thickness of the thin film lithium niobate flat optical waveguide is 10nm-500nm, and the thickness of the thin film lithium niobate straight waveguide is 100nm-500 nm.
Furthermore, the thickness of the upper layer metal electrode of the ground electrode and the signal electrode is 100nm-2 μm, and the thickness of the lower layer metal electrode of the ground electrode and the signal electrode is 10nm-500 nm; the distances between the upper layer metal electrodes of the signal electrodes and the upper layer metal electrodes of the ground electrodes on the two sides are the same and are both 5-50 mu m; the distances between the lower metal electrodes of the signal electrodes and the lower metal electrodes of the ground electrodes on the two sides are the same and are 3-5 mu m.
Furthermore, the widths of the upper layer metal electrodes of the two ground electrodes are the same and are both 10-400 μm; the widths of the lower metal electrodes of the two ground electrodes are the same and are both 15-500 mu m; the width of an upper layer metal electrode of the signal electrode is 5-100 mu m; the width of the lower metal electrode of the signal electrode is 10-200 μm.
Compared with the prior art, the invention has the beneficial effects that:
1. the thin-film lithium niobate electro-optical switch provided by the invention adopts a double-layer metal electrode structure on the electrode structure, can effectively reduce the driving voltage of the electro-optical switch, and simultaneously ensures perfect electro-optical wave velocity matching.
2. The thin-film lithium niobate electro-optical switch provided by the invention is additionally provided with deep etching areas in the input coupler and the output coupler, and can effectively reduce the optical crosstalk caused by the thin-film lithium niobate flat optical waveguide, thereby reducing the optical crosstalk of the output port of the optical switch.
Drawings
FIG. 1 is an overall schematic diagram of a thin-film lithium niobate electro-optical switch according to the present invention;
FIG. 2 is a schematic structural diagram of a thin-film lithium niobate electro-optical switch in embodiment 1 of the present invention;
fig. 3 is a schematic structural diagram of a thin-film lithium niobate electro-optical switch in embodiment 2 of the present invention;
fig. 4 is a schematic structural diagram of a thin-film lithium niobate electro-optical switch in embodiment 3 of the present invention;
FIG. 5 is a schematic structural diagram of a thin-film lithium niobate electro-optical switch in embodiment 4 of the present invention;
FIG. 6 is a sectional view taken along line A-A' of FIG. 1;
fig. 7 is a sectional view taken along line B-B' in fig. 1.
In the figure: 100. a substrate; 200. a lower cladding; 300. thin film lithium niobate slab optical waveguides; 400. an electro-optical switching assembly; 410. an input coupler; 411. a first input optical waveguide; 412. a first multimode interference zone; 413. a first output optical waveguide; 414. a first deep etching region; 420. an electro-optically active region; 421. a signal electrode; 4211. an upper metal electrode I; 4212. a lower metal electrode I; 422. a ground electrode; 4221. an upper metal electrode II; 4222. a lower metal electrode II; 423. a thin film lithium niobate straight waveguide; 430. an output coupler; 431. a second input optical waveguide; 432. a second multimode interference region; 433. a second output optical waveguide; 434. a second deep etching region; 500. and (4) an upper cladding layer.
Detailed Description
In order to make the technical field of the invention better understand the scheme of the invention, the following detailed description of the embodiments of the invention is provided in conjunction with the accompanying drawings and the implementation mode.
An embodiment of the present invention provides a thin-film lithium niobate electro-optical switch, as shown in fig. 1 to 7, including a substrate 100, a lower cladding 200, a thin-film lithium niobate slab optical waveguide 300, an electro-optical switch assembly 400, and an upper cladding 500 stacked from bottom to top, where the electro-optical switch assembly 400 includes:
an input coupler 410, an electro-optically active region 420, and an output coupler 430 disposed on the thin film lithium niobate slab optical waveguide 300 in this order along the optical path, wherein,
the input coupler 410 has at least one first input optical waveguide 411, a first multimode interference region 412 and two first output optical waveguides 413, the first input optical waveguide 411, the first multimode interference region 412 and the first output optical waveguides 413 being connected in sequence;
the output coupler 430 has two second input optical waveguides 431, a second multimode interference region 432 and at least one second output optical waveguide 433, and the second input optical waveguides 431, the second multimode interference region 432 and the second output optical waveguide 433 are connected in sequence;
the electro-optical action region 420 is provided with a ground electrode 422 and a signal electrode 421, the ground electrode 422 is positioned at two sides of the signal electrode 421, and a thin-film lithium niobate straight waveguide 423 is arranged between the ground electrode 422 and the signal electrode 421;
the ground electrode 422 and the signal electrode 421 both have an upper layer metal electrode and a lower layer metal electrode arranged from top to bottom, and the thickness of the upper layer metal electrode is greater than that of the lower layer metal electrode.
The thin film lithium niobate flat plate optical waveguide 300 is provided with a first deep etching area 414 in the area between the two first output optical waveguides 413; the area of the thin film lithium niobate slab waveguide 300 between the two second input waveguides 431 is provided with a second deep etching region 434.
The cross section of the thin film lithium niobate straight waveguide 423 is trapezoidal.
The input ends of the thin-film lithium niobate straight waveguides 423 are respectively connected with the two first output optical waveguides 413, and the output ends of the thin-film lithium niobate straight waveguides are respectively connected with the two second input optical waveguides 431.
The tops of the upper metal electrodes of the ground electrode 422 and the signal electrode 421 both extend out of the upper cladding 500, and the materials of the upper cladding 500 and the lower cladding 200 are both silicon dioxide.
The thickness of the lower cladding layer 200 is 1 μm to 5 μm; the thickness of the upper cladding layer 500 is 1 μm to 3 μm.
The widths of the first and second input optical waveguides 431, the first and second output optical waveguides 433 and the thin-film lithium niobate straight waveguide 423 are all 500nm-2 μm, and the widths of the first and second multimode interference regions are 6 μm-100 μm.
The thickness of the thin film lithium niobate flat optical waveguide 300 is 10nm-500nm, and the thickness of the thin film lithium niobate straight waveguide 423 is 10nm-500 nm.
The thickness of the upper layer metal electrodes of the ground electrode 422 and the signal electrode 421 is 100nm-2 μm, and the thickness of the lower layer metal electrodes of the ground electrode 422 and the signal electrode 421 is 100nm-500 nm; the distances between the upper layer metal electrodes of the signal electrodes 421 and the upper layer metal electrodes of the ground electrodes 422 on the two sides are the same and are both 5-50 μm; the distances between the lower metal electrodes of the signal electrodes 421 and the lower metal electrodes of the ground electrodes 422 on both sides are the same, and are all 3 μm to 5 μm.
The widths of the upper metal electrodes of the two ground electrodes 422 are the same and are both 10-400 μm; the widths of the lower metal electrodes of the two ground electrodes 422 are the same and are both 15-500 μm; the width of the upper metal electrode of the signal electrode 421 is 5 μm-100 μm; the width of the lower metal electrode of the signal electrode 421 is 10 μm to 200 μm.
Example 1:
the input coupler 410 has a first input optical waveguide 411, a first multimode interference region 412 and two first output optical waveguides 413 connected in this order; the output coupler 430 has two second input optical waveguides 431, a second multimode interference region 432 and one second output optical waveguide 433 which are connected in sequence; and a single-input single-output thin-film lithium niobate electro-optical switch is formed.
The thickness of the thin film lithium niobate flat optical waveguide 300 is 300nm, the thickness of the thin film lithium niobate straight waveguide 423 is 300nm, the thickness of the ground electrode 422 and the lower layer metal electrodes I4212 and II 4222 of the signal electrode 421 are both 300nm, the thickness of the ground electrode 422 and the upper layer metal electrodes I4211 and II 4221 of the signal electrode 421 are both 1.5 μm, the distance between the lower layer metal electrode I4212 of the signal electrode 421 and the lower layer metal electrodes II 4222 of the ground electrodes 422 on both sides is both 3 μm, the width of the lower layer metal electrode I4212 of the signal electrode 421 is 10 μm, the width of the lower layer metal electrode II 4222 of the ground electrode 422 is both 15 μm, the distance between the upper layer metal electrode I4211 of the signal electrode 421 and the upper layer metal electrodes II 4221 of the ground electrodes 422 on both sides is 5 μm, the width of the upper layer metal electrode I4211 of the signal electrode 421 is 7 μm, the width of the upper layer metal electrode 4221 of the ground electrode 422 is both 13.5 μm, the thickness of the lower cladding layer 200 was 2 μm, and the thickness of the upper cladding layer 500 was 2 μm.
Example 2:
the input coupler 410 has two first input optical waveguides 411, a first multimode interference region 412, and two first output optical waveguides 413 connected in this order; the output coupler 430 has two second input optical waveguides 431, a second multimode interference region 432 and one second output optical waveguide 433 which are connected in sequence; the double-input single-output thin-film lithium niobate electro-optical switch is formed.
The thickness of the thin film lithium niobate flat optical waveguide 300 is 200nm, the thickness of the thin film lithium niobate straight waveguide 423 is 400nm, the thickness of the ground electrode 422 and the lower layer metal electrodes I4212 and II 4222 of the signal electrode 421 are both 400nm, the thickness of the ground electrode 422 and the upper layer metal electrodes I4211 and II 4221 of the signal electrode 421 are both 1.6 μm, the distance between the lower layer metal electrode I4212 of the signal electrode 421 and the lower layer metal electrodes II 4222 of the ground electrodes 422 on both sides is both 5 μm, the width of the lower layer metal electrode I4212 of the signal electrode 421 is 15 μm, the width of the lower layer metal electrode II 4222 of the ground electrode 422 is both 25 μm, the distance between the upper layer metal electrode I4211 of the signal electrode 421 and the upper layer metal electrodes II 4221 of the ground electrodes 422 on both sides is 10 μm, the width of the upper layer metal electrode I4211 of the signal electrode 421 is 10 μm, and the width of the upper layer metal electrode 4221 of the ground electrode 422 is both 20 μm, the thickness of the lower cladding layer 200 was 2 μm, and the thickness of the upper cladding layer 500 was 2 μm.
Example 3:
the input coupler 410 has two first input optical waveguides 411, a first multimode interference region 412, and two first output optical waveguides 413 connected in this order; the output coupler 430 has two second input optical waveguides 431, a second multimode interference region 432 and two second output optical waveguides 433 which are connected in sequence; and forming the double-input double-output thin-film lithium niobate electro-optical switch.
The thickness of the thin film lithium niobate flat optical waveguide 300 is 100nm, the thickness of the thin film lithium niobate straight waveguide 423 is 400nm, the thicknesses of the ground electrode 422 and the lower layer metal electrodes I4212 and II 4222 of the signal electrode 421 are both 500nm, the thicknesses of the ground electrode 422 and the upper layer metal electrodes I4211 and II 4221 of the signal electrode 421 are both 1.5 μm, the distance between the lower layer metal electrode I4212 of the signal electrode 421 and the lower layer metal electrodes II 4222 of the ground electrodes 422 on both sides is both 3 μm, the width of the lower layer metal electrode I4212 of the signal electrode 421 is 10 μm, the width of the lower layer metal electrode II 4222 of the ground electrode 422 is both 15 μm, the distance between the upper layer metal electrode I4211 of the signal electrode 421 and the upper layer metal electrodes II 4221 of the ground electrodes 422 on both sides is 5 μm, the width of the upper layer metal electrode I4211 of the signal electrode 421 is 7 μm, and the width of the upper layer metal electrode 4221 of the ground electrode 422 is both 13.5 μm, the thickness of the lower cladding layer 200 was 2 μm, and the thickness of the upper cladding layer 500 was 2 μm.
Example 4:
the input coupler 410 has a first input optical waveguide 411, a first multimode interference region 412 and two first output optical waveguides 413 connected in this order; the output coupler 430 has two second input optical waveguides 431, a second multimode interference region 432 and two second output optical waveguides 433 which are connected in sequence; the single-input double-output thin-film lithium niobate electro-optical switch is formed.
The thickness of the thin-film lithium niobate flat-plate optical waveguide 300 is 300nm, the thickness of the thin-film lithium niobate straight waveguide 423 is 300nm, the thicknesses of the ground electrode 422 and the lower-layer metal electrodes I4212 and II 4222 of the signal electrode 421 are both 300nm, the thicknesses of the ground electrode 422 and the upper-layer metal electrodes I4211 and II 4221 of the signal electrode 421 are both 1.5 μm, the distance between the lower-layer metal electrode I4212 of the signal electrode 421 and the lower-layer metal electrodes II 4222 of the ground electrodes 422 on both sides is both 5 μm, the width of the lower-layer metal electrode I4212 of the signal electrode 421 is 15 μm, the width of the lower-layer metal electrode II 4222 of the ground electrode 422 is both 25 μm, the distance between the upper-layer metal electrode I4211 of the signal electrode 421 and the upper-layer metal electrodes II 4221 of the ground electrodes 422 on both sides is 10 μm, the width of the upper-layer metal electrode I4211 of the signal electrode 421 is 10 μm, and the width of the upper-layer metal electrode 42, the thickness of the lower cladding layer 200 was 2 μm, and the thickness of the upper cladding layer 500 was 2 μm.
According to the invention, the distance between the electrodes is reduced by adopting the double-layer electrodes with different upper and lower thicknesses, so that the driving voltage is reduced, and the wave velocity is matched. The size of the driving voltage is related to the distance between the electrodes, the smaller the distance is, the lower the driving voltage is, and because the thick metal electrode has strong absorption to light (generally 1um to 10um, in order to ensure that an electro-optical device has a fast response speed, the electro-optical needs wave velocity matching, and the metal electrode cannot be too thin), the distance between the electrode and the waveguide cannot be too small, so that the reduction of the driving voltage is limited, and the gap between the electrode and the waveguide is generally larger than 1.5 um; the lower layer electrode of the double-layer electrode structure is very thin, and the absorption of light is weak, so that the distance between the electrodes can be reduced, the driving voltage is reduced, meanwhile, the larger distance is kept between the thick metal electrodes of the upper layer, and the wave velocity matching can still be ensured.
In addition, the invention can effectively reduce the optical crosstalk brought by the thin film lithium niobate slab optical waveguide by performing deep etching on the input optical waveguide and the output optical waveguide, thereby reducing the optical crosstalk of the output port of the optical switch, wherein the thin film lithium niobate slab optical waveguide and the thin film lithium niobate straight waveguide form the thin film lithium niobate ridge waveguide, the optical field is generally limited in the middle of the whole thin film lithium niobate ridge waveguide, at the moment, the thin film lithium niobate slab optical waveguide area has evanescent field distribution, when the two thin film lithium niobate ridge waveguides are close to each other (less than 50um, theoretically, the coupling condition is that the distance between the two waveguides is infinite, in practical situation, the coupling cannot be generated when the distance is greater than 50 um), the optical field energy can be coupled from one waveguide to the adjacent waveguide through the evanescent field in the thin film lithium niobate slab optical waveguide area, which can cause the crosstalk between the two output channels of the electro-optical switch, the isolation is reduced, a deep etching area is added between the input/output optical waveguides, and the thin film lithium niobate flat optical waveguide is etched through, so that coupling of an evanescent field can be prevented, further crosstalk is reduced, and the isolation is improved.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention.
Claims (10)
1. A thin-film lithium niobate electro-optical switch comprises a substrate, a lower cladding, a thin-film lithium niobate flat optical waveguide, an electro-optical switch component and an upper cladding which are stacked from bottom to top, and is characterized in that the electro-optical switch component comprises:
an input coupler, an electro-optic active region and an output coupler arranged on the thin film lithium niobate slab optical waveguide along the optical path in sequence, wherein,
the input coupler is provided with at least one first input optical waveguide, a first multimode interference region and two first output optical waveguides, and the first input optical waveguide, the first multimode interference region and the first output optical waveguides are sequentially connected;
the output coupler is provided with two second input optical waveguides, a second multimode interference region and at least one second output optical waveguide, and the second input optical waveguides, the second multimode interference region and the second output optical waveguides are sequentially connected;
the electro-optical action region is provided with a ground electrode and a signal electrode, the ground electrode is positioned at two sides of the signal electrode, and a thin-film lithium niobate straight waveguide is arranged between the ground electrode and the signal electrode;
the ground electrode and the signal electrode are both provided with an upper layer metal electrode and a lower layer metal electrode which are arranged from top to bottom, and the thickness of the upper layer metal electrode is larger than that of the lower layer metal electrode.
2. The thin-film lithium niobate electro-optical switch of claim 1, wherein: the thin film lithium niobate flat optical waveguide is provided with a first deep etching area in the area between the two first output optical waveguides; the area of the thin film lithium niobate flat optical waveguide between the two second input optical waveguides is provided with a second deep etching area.
3. The thin-film lithium niobate electro-optical switch of claim 1, wherein: the cross section of the thin film lithium niobate straight waveguide is trapezoidal.
4. The thin-film lithium niobate electro-optical switch of claim 1, wherein: the input ends of the thin-film lithium niobate straight waveguides are respectively connected with the two first output optical waveguides, and the output ends of the thin-film lithium niobate straight waveguides are respectively connected with the second input optical waveguides.
5. The thin-film lithium niobate electro-optical switch of claim 1, wherein: the top parts of the upper-layer metal electrodes of the ground electrode and the signal electrode extend out of the upper cladding, and the upper cladding and the lower cladding are made of silicon dioxide.
6. The thin-film lithium niobate electro-optical switch of claim 5, wherein: the thickness of the lower cladding is 1-5 μm; the thickness of the upper cladding layer is 1-3 μm.
7. The thin-film lithium niobate electro-optical switch of claim 1, wherein: the widths of the first input optical waveguide, the second input optical waveguide, the first output optical waveguide, the second output optical waveguide and the thin-film lithium niobate straight waveguide are all 500nm-2 mu m, and the widths of the first multimode interference area and the second multimode interference area are 6 mu m-100 mu m.
8. The thin-film lithium niobate electro-optical switch of claim 1, wherein: the thickness of the thin film lithium niobate flat optical waveguide is 10nm-500nm, and the thickness of the thin film lithium niobate straight waveguide is 100nm-500 nm.
9. The thin-film lithium niobate electro-optical switch of claim 1, wherein: the thickness of the upper layer metal electrode of the ground electrode and the signal electrode is 100nm-2 μm, and the thickness of the lower layer metal electrode of the ground electrode and the signal electrode is 10nm-500 nm; the distances between the upper layer metal electrodes of the signal electrodes and the upper layer metal electrodes of the ground electrodes on the two sides are the same and are both 5-50 mu m; the distances between the lower metal electrodes of the signal electrodes and the lower metal electrodes of the ground electrodes on the two sides are the same and are 3-5 mu m.
10. The thin-film lithium niobate electro-optical switch of claim 1, wherein: the widths of the upper metal electrodes of the two ground electrodes are the same and are both 10-400 mu m; the widths of the lower metal electrodes of the two ground electrodes are the same and are both 15-500 mu m; the width of an upper layer metal electrode of the signal electrode is 5-100 mu m; the width of the lower metal electrode of the signal electrode is 10-200 μm.
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