CN211786458U - Thin-film electro-optic modulator chip and modulator - Google Patents
Thin-film electro-optic modulator chip and modulator Download PDFInfo
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- CN211786458U CN211786458U CN202020649775.2U CN202020649775U CN211786458U CN 211786458 U CN211786458 U CN 211786458U CN 202020649775 U CN202020649775 U CN 202020649775U CN 211786458 U CN211786458 U CN 211786458U
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Abstract
The utility model discloses a film electro-optic modulator chip, include: the optical waveguide comprises a base wafer, an adhesive layer, a film substrate, an optical waveguide and a metal electrode, wherein the film substrate is arranged above the base wafer, the adhesive layer is arranged between the base wafer and the film substrate, the metal electrode is arranged on the upper surface of the film substrate, and the optical waveguide is formed in the film substrate and arranged at the bottom of the film substrate. Correspondingly, the application also provides a thin film electro-optic modulator. The utility model provides a film electro-optic modulator chip and film electro-optic modulator structure can realize the preparation of titanium diffusion, zinc oxide diffusion plasma high temperature diffusion optical waveguide in the electro-optic crystal film of bonding on the basement wafer, and can not destroy bonding structure's validity between crystal film and the basement wafer, realizes the preparation of high modulation bandwidth, low half-wave voltage's film electro-optic modulator.
Description
Technical Field
The utility model discloses can be applied to technical field such as fiber communication, optical fiber sensing, quantum communication, concretely relates to film electro-optic modulator chip and modulator.
Background
An electro-optical modulator obtained by manufacturing an optical waveguide structure in an electro-optical crystal, for example, a lithium niobate electro-optical modulator based on a titanium diffusion optical waveguide, has significant advantages of high on-off extinction ratio, high linearity, low chirp and the like, and is widely applied to a high-speed optical fiber communication system. However, the existing lithium niobate electro-optic modulator needs to design and manufacture a very complicated coplanar waveguide traveling wave electrode structure to realize a high modulation bandwidth (such as 10 GHz-50 GHz) due to a high dielectric constant, but the performance sacrificed by the lithium niobate electro-optic modulator is a high half-wave voltage and a high radio frequency driving power consumption under a high frequency.
In recent years, with the maturity of lithium niobate crystal bonding technology and thinning technology, the lithium niobate thin film bonded on the low dielectric constant substrate crystal has shown great advantages in the aspect of preparing the electro-optical modulator with high modulation bandwidth and low half-wave voltage. However, the preparation of the titanium-diffused optical waveguide on the bonded lithium niobate thin film cannot be realized because the process temperature (1000 ℃) is far beyond the tolerable upper temperature limit of the bonded structure, because the debonding and bonding of the lithium niobate thin film and the substrate crystal can occur at the titanium diffusion process temperature, and the low-loss titanium-diffused optical waveguide cannot be successfully prepared under the temperature condition of being lower than 900 ℃.
SUMMERY OF THE UTILITY MODEL
In view of the above, an object of the present invention is to provide a thin film electro-optic modulator chip and a modulator, which can place an optical waveguide at the bottom of a thin film substrate, and can effectively implement the preparation of a titanium diffusion plasma high temperature diffusion optical waveguide in the electro-optic thin film substrate and the preparation of the thin film electro-optic modulator based on the optical waveguide by preparing the optical waveguide first and then performing crystal bonding and thin film processing.
In order to realize the utility model discloses a purpose, the utility model provides a pair of film electro-optic modulator chip, include: a base wafer, an adhesive layer, a film substrate, an optical waveguide, and a metal electrode,
the thin film substrate is placed above the base wafer, the bonding layer is placed between the base wafer and the thin film substrate, the metal electrode is placed on the upper surface of the thin film substrate, and the optical waveguide is formed in the thin film substrate and placed at the bottom of the thin film substrate.
Further, the optical waveguide is an ion high temperature diffusion waveguide.
Further, the optical waveguide is a titanium diffusion waveguide, a zinc diffusion waveguide or a zinc oxide diffusion waveguide.
Further, the optical waveguide and the metal electrode adopt one of the following four structures:
the first method comprises the following steps: the optical waveguide is a straight strip waveguide structure, the metal electrode comprises a metal electrode branch I and a metal electrode branch II, a lumped electrode structure is formed, and an electric field is distributed among the metal electrode branches to modulate light waves in the optical waveguide;
and the second method comprises the following steps: the optical waveguide is a Mach-Zehnder interferometer-shaped waveguide structure, the metal electrode comprises a first metal electrode branch and a second metal electrode branch to form a push-pull type lumped electrode structure, and an electric field is distributed between the metal electrode branches to modulate light waves in the optical waveguide;
and the third is that: the optical waveguide is a straight strip waveguide structure, the metal electrode comprises a signal electrode and a grounding electrode, and a traveling wave electrode structure is formed, and the signal electrode and the grounding electrode are formed in an asymmetric microstrip line structure or a coplanar waveguide structure;
and fourthly: the optical waveguide is a Mach-Zehnder interferometer-shaped waveguide structure, the metal electrode comprises a signal electrode and a grounding electrode, a traveling wave electrode structure is formed, and the signal electrode and the grounding electrode are formed in a push-pull coplanar waveguide structure.
Further, in the first and second metal electrode structures, the distance between the first metal electrode branch and the second metal electrode branch is 3-20 μm.
Further, in the third and fourth metal electrode structures, the width of the signal electrode is 3 to 100 μm, and the interval between the signal electrode and the ground electrode is 3 to 50 μm.
Further, the substrate wafer is made of lithium niobate, lithium tantalate or silicon, quartz or sapphire, and the thickness of the substrate wafer is 0.2mm to 2 mm.
Further, the crystal tangential direction of the film substrate is X-cut, and the thickness of the film substrate is not more than 20 microns.
Furthermore, the bonding layer is made of silicon oxide, magnesium oxide or tantalum oxide, titanium oxide, silicon nitride or benzocyclobutene, and the thickness of the bonding layer is 0.1-5 microns.
Correspondingly, the application also provides a thin-film electro-optic modulator which comprises the thin-film electro-optic modulator chip.
Compared with the prior art, the beneficial effects of the utility model are that, the utility model provides a film electro-optic modulator chip and film electro-optic modulator structure can realize the preparation of titanium diffusion, zinc oxide diffusion plasma high temperature diffusion optical waveguide in the electro-optic crystal film of bonding on the basement wafer, and can not destroy the validity of bonding structure between crystal film and the basement wafer, realizes the preparation of the film electro-optic modulator of high modulation bandwidth, low half-wave voltage.
Drawings
FIG. 1A: the utility model discloses the thin film electro-optic modulator that the first embodiment shows overlooks the schematic diagram of the structure;
FIG. 1B: FIG. 1A is a schematic cross-sectional view taken along the line A-A';
FIG. 2A: the thin film electro-optic modulator shown in the second embodiment of the present invention has a schematic top view structure;
FIG. 2B: FIG. 2A is a schematic cross-sectional view taken along line B-B';
FIG. 3A: the utility model discloses a thin film electro-optic modulator based on asymmetric microstrip line electrode structure that third embodiment shows overlooks the schematic diagram of structure;
FIG. 3B: the utility model discloses the thin film electro-optic modulator of the base coplanar waveguide electrode structure that third embodiment shows overlooks the schematic diagram of the structure;
FIG. 3C: FIG. 3A is a schematic cross-sectional view taken along the dashed line C-C';
FIG. 3D: FIG. 3B is a schematic cross-sectional view taken along the dashed line D-D
FIG. 4A: the thin film electro-optic modulator shown in the fourth embodiment of the present invention has a schematic top view structure;
FIG. 4B: FIG. 4A is a schematic cross-sectional view taken along the dashed line E-E';
FIG. 5: the utility model relates to a flow chart of a preparation method of a thin film electro-optic modulator;
the names corresponding to each mark in the figure are respectively: 1. a base wafer; 2. an adhesive layer; 3. a thin film substrate; 4. an optical waveguide; 51. the metal electrode is branched I; 52. a second metal electrode branch; 53. a signal electrode; 54. a ground electrode; 6. the film is to be diffused.
Detailed Description
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 invention will be described in further detail with reference to the following drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The utility model provides a film electro-optic modulator chip, include: the substrate wafer 1, the adhesive layer 2, the film substrate 3, the optical waveguide 4, and the metal electrode.
The base wafer 1 can provide mechanical support for the thin film substrate 3, and the material thereof can be any one of crystal materials such as lithium niobate, lithium tantalate, silicon, quartz, sapphire and the like, and is preferably quartz. The thickness of the base wafer 1 can be between 0.2mm and 2mm, preferably 1 mm.
The film substrate 3 is disposed above the base wafer 1, and the material of the film substrate is optical grade crystal with Pockels linear electro-optical effect, such as lithium niobate, lithium tantalate, potassium titanyl phosphate, gallium arsenide, etc., or magnesium-doped or magnesium oxide-doped lithium niobate or lithium tantalate, or near stoichiometric lithium niobate or lithium tantalate, etc. The crystal of the thin-film substrate 3 is preferably cut in the tangential direction by X and has a thickness of not more than 20 μm.
The adhesive layer 2 is disposed between the base wafer 1 and the film substrate 3, and may be made of any one of non-metal materials such as silicon oxide, magnesium oxide, tantalum oxide, titanium oxide, and silicon nitride, or may be made of benzocyclobutene (BCB) polymer material. The thickness of the adhesive layer 2 is 0.1 to 5 μm. The adhesive layer 2 serves as a bonding transition layer between the base wafer 1 and the film substrate 3, and also serves as a spatial constraint for light waves in the vertical direction.
The optical waveguide 4 is formed in the thin film substrate 3 and placed at the bottom of the thin film substrate 3. The optical waveguide 4 may be formed by high-temperature diffusion of titanium, zinc, or zinc oxide. Since the optical waveguide formed by ion high temperature diffusion is generally prepared at a higher temperature (generally not less than 900 ℃), which is far beyond the effectiveness of the crystal bonding structure between the thin film substrate 3 and the base wafer 1. Therefore, the optical waveguide 4 is formed in the thin film substrate 3 by firstly manufacturing the optical waveguide 4 on the surface of the bulk electro-optic crystal, then bonding the crystal face of the bulk electro-optic crystal on which the optical waveguide 4 is formed with the base wafer 1, and finally thinning the bulk electro-optic crystal to manufacture the thin film substrate 3 on which the optical waveguide 4 is formed. Therefore, in the thin film substrate 3, the optical waveguide 4 is placed at the bottom thereof.
The metal electrode is arranged on the upper surface of the thin film substrate 3, and the phase of the light wave transmitted in the optical waveguide 4 can be modulated through the electro-optic effect of the thin film substrate 3. The metal electrode can adopt a lumped electrode structure or a traveling wave electrode structure. The metal electrode is composed of a double-layer metal film of titanium-gold or chromium-gold, or the like, or a multilayer metal film of titanium-platinum-gold, chromium-platinum-gold, or the like, preferably a chromium-gold double-layer metal film, wherein the titanium metal or chromium metal layer is used for improving the adhesion between the gold film and the film substrate 3. In order to ensure enough adhesion between the metal electrode and the thin film substrate 3 and enough modulation speed of the electro-optical modulator, the thickness of the chromium film is 10 nm-200 nm, and the thickness of the gold film is 0.1 mu m-40 mu m.
The structure of the thin film electro-optic modulator chip according to the present invention will be described below with reference to examples.
Example one
Fig. 1A is a schematic top view of the thin-film electro-optic modulator shown in this embodiment, and fig. 1B is a schematic cross-sectional view taken along the dashed line a-a' in fig. 1A.
In the present embodiment, the optical waveguide 4 is a straight waveguide structure, and the electro-optical modulator formed by the optical waveguide is a phase modulator. The metal electrode comprises a first metal electrode branch 51 and a second metal electrode branch 52, which form a lumped electrode structure, and the electric field is distributed between the first metal electrode branch 51 and the second metal electrode branch 52 to modulate the light wave in the optical waveguide 4. The distance G1 between the first metal electrode branch 51 and the second metal electrode branch 52 is 3-20 μm.
Example two
Fig. 2A is a schematic top view of the thin-film electro-optic modulator shown in this embodiment, and fig. 2B is a schematic cross-sectional view taken along the dashed line B-B' in fig. 3A.
In the present embodiment, the optical waveguide 4 has a Mach-Zehnder (Mach-Zehnder) interferometer waveguide structure, and the electro-optical modulator formed by the waveguide is an intensity modulator. The metal electrode comprises a first metal electrode branch 51 and a second metal electrode branch 52, which form a push-pull type lumped electrode structure, and the electric field is distributed between the first metal electrode branch 51 and the second metal electrode branch 52 to modulate the light wave in the optical waveguide 4. The distance G1 between the first metal electrode branch 51 and the second metal electrode branch 52 is 3-20 μm.
EXAMPLE III
Fig. 3A and 3B are schematic top-view structural diagrams of the thin-film electro-optic modulator shown in the present embodiment, fig. 3C is a schematic cross-sectional structural diagram taken along a dashed line C-C 'in fig. 3A, and fig. 3D is a schematic cross-sectional structural diagram taken along a dashed line D-D' in fig. 3B.
In the present embodiment, the optical waveguide 4 is a straight waveguide structure, and the electro-optical modulator formed by the optical waveguide is a phase modulator. The metal electrode includes a signal electrode 53 and a ground electrode 54, and is formed in a traveling wave electrode structure, where the signal electrode 53 and the ground electrode 54 may be formed in an asymmetric microstrip line structure as shown in fig. 3A and 3B, or in a coplanar waveguide structure as shown in fig. 3C and 3D. The width W of the signal electrode 53 is 3 μm to 100 μm, and the gap G2 between the signal electrode and the ground electrode 54 is 3 μm to 50 μm.
Example four
Fig. 4A is a schematic top view of the thin-film electro-optic modulator shown in this embodiment, and fig. 4B is a schematic cross-sectional view taken along the dashed line E-E' in fig. 4A.
In the present embodiment, the optical waveguide 4 has a Mach-Zehnder (Mach-Zehnder) interferometer waveguide structure, and the electro-optical modulator formed by the waveguide is an intensity modulator. The metal electrode includes a signal electrode 53 and a ground electrode 54, and is configured in a traveling wave electrode structure, and the signal electrode 53 and the ground electrode 54 are configured in a push-pull coplanar waveguide structure. The width W of the signal electrode 53 is 3 μm to 100 μm, and the gap G2 between the signal electrode and the ground electrode 54 is 3 μm to 50 μm.
Correspondingly, the utility model also provides a thin film electro-optical modulator who uses above-mentioned thin film electro-optical modulator chip, thin film electro-optical modulator still includes publicly known parts such as optic fibre crystal carrier block, optic fibre, encapsulation tube certainly, no longer details in this patent.
In addition, the utility model provides a preparation method of above-mentioned thin film electro-optic modulator chip, refer to the schematic flow chart that fig. 5 shows. The preparation method comprises the following main steps:
step 1: preparing a film 6 to be diffused with an optical waveguide pattern, such as a titanium film, a zinc film or a zinc oxide film, on the surface of a bulk material wafer (such as lithium niobate or lithium tantalate) by adopting a conventional semiconductor process technology, wherein the thickness of the film is not more than 200 nm;
step 2: placing the bulk material wafer into the center of a high-temperature diffusion furnace for diffusion to form an optical waveguide 4 on the surface of the wafer;
and step 3: plating a non-metal film (such as silicon oxide, silicon nitride and the like) on a crystal face of a bulk material wafer on which the optical waveguide 4 is formed by a film plating method such as PECVD (plasma enhanced chemical vapor deposition) and the like to be used as an adhesive layer 2, and flattening and polishing the adhesive layer film by a polishing method such as Chemical Mechanical Polishing (CMP) and the like;
and 4, step 4: bonding the polished film surface of the bonding layer with the substrate chip 1 by adopting a wafer-level bonding process;
and 5: grinding, polishing and other thinning treatment are carried out on one surface, far away from the optical waveguide, of the bonded bulk material wafer until the bulk material wafer is thinned to the thickness not more than 20 microns, and a thin film substrate 3 is obtained, and the optical waveguide 4 is placed at the bottom of the thin film substrate 3;
step 6: and a metal electrode structure is manufactured on the upper surface of the film substrate 3 by adopting conventional semiconductor process technologies such as photoetching, film coating, electroplating and the like.
The technical means not described in detail in the present application are known techniques.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, a plurality of improvements and decorations can be made without departing from the principle of the present invention, and these improvements and decorations should also be regarded as the protection scope of the present invention.
Claims (10)
1. A thin film electro-optic modulator chip, comprising: a base wafer, an adhesive layer, a film substrate, an optical waveguide, and a metal electrode,
the thin film substrate is placed above the base wafer, the bonding layer is placed between the base wafer and the thin film substrate, the metal electrode is placed on the upper surface of the thin film substrate, and the optical waveguide is formed in the thin film substrate and placed at the bottom of the thin film substrate.
2. The thin film electro-optic modulator chip of claim 1, wherein the optical waveguide is an ion high temperature diffusion waveguide.
3. The thin film electro-optic modulator chip of claim 1, wherein the optical waveguide is a titanium diffused waveguide, a zinc diffused waveguide, or a zinc oxide diffused waveguide.
4. A thin film electro-optic modulator chip as claimed in any one of claims 1 to 3 wherein said optical waveguide and said metal electrode are in one of four configurations:
the first method comprises the following steps: the optical waveguide is a straight strip waveguide structure, the metal electrode comprises a metal electrode branch I and a metal electrode branch II, a lumped electrode structure is formed, and an electric field is distributed among the metal electrode branches to modulate light waves in the optical waveguide;
and the second method comprises the following steps: the optical waveguide is a Mach-Zehnder interferometer-shaped waveguide structure, the metal electrode comprises a first metal electrode branch and a second metal electrode branch to form a push-pull type lumped electrode structure, and an electric field is distributed between the metal electrode branches to modulate light waves in the optical waveguide;
and the third is that: the optical waveguide is a straight strip waveguide structure, the metal electrode comprises a signal electrode and a grounding electrode, and a traveling wave electrode structure is formed, and the signal electrode and the grounding electrode are formed in an asymmetric microstrip line structure or a coplanar waveguide structure;
and fourthly: the optical waveguide is a Mach-Zehnder interferometer-shaped waveguide structure, the metal electrode comprises a signal electrode and a grounding electrode, a traveling wave electrode structure is formed, and the signal electrode and the grounding electrode are formed in a push-pull coplanar waveguide structure.
5. A thin film electro-optic modulator chip as claimed in claim 4 wherein the first and second metal electrode structures have a spacing of 3 μm to 20 μm between the first metal electrode branches and the second metal electrode branches.
6. A thin-film electro-optic modulator chip as claimed in claim 4 wherein in the third and fourth metal electrode configurations, the signal electrode has a width of 3 μm to 100 μm and is spaced from the ground electrode by a distance of 3 μm to 50 μm.
7. A thin film electro-optic modulator chip as claimed in claim 4 wherein said substrate wafer is made of lithium niobate, lithium tantalate or silicon, quartz, sapphire with a thickness of 0.2mm to 2 mm.
8. The thin-film electro-optic modulator chip of claim 4, wherein the thin-film substrate has a crystal tangent of X-cut and a thickness of not more than 20 μm.
9. The thin-film electro-optic modulator chip of claim 4, wherein the adhesive layer is made of silicon oxide, magnesium oxide or tantalum oxide, titanium oxide, silicon nitride or benzocyclobutene, and has a thickness of 0.1 μm to 5 μm.
10. A thin-film electro-optic modulator comprising a thin-film electro-optic modulator chip as claimed in claim 4.
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| CN112764246A (en) * | 2021-01-27 | 2021-05-07 | 浙江大学 | Thin-film lithium niobate electro-optical modulator and preparation method thereof |
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| CN112764246A (en) * | 2021-01-27 | 2021-05-07 | 浙江大学 | Thin-film lithium niobate electro-optical modulator and preparation method thereof |
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