CN117348160A - Vertical optical coupling device based on thin film lithium niobate waveguide and preparation method thereof - Google Patents
Vertical optical coupling device based on thin film lithium niobate waveguide and preparation method thereof Download PDFInfo
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- CN117348160A CN117348160A CN202311296629.0A CN202311296629A CN117348160A CN 117348160 A CN117348160 A CN 117348160A CN 202311296629 A CN202311296629 A CN 202311296629A CN 117348160 A CN117348160 A CN 117348160A
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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 110
- 230000003287 optical effect Effects 0.000 title claims abstract description 36
- 230000008878 coupling Effects 0.000 title claims abstract description 35
- 238000010168 coupling process Methods 0.000 title claims abstract description 35
- 238000005859 coupling reaction Methods 0.000 title claims abstract description 35
- 239000010409 thin film Substances 0.000 title claims abstract description 28
- 238000002360 preparation method Methods 0.000 title abstract description 5
- 238000005253 cladding Methods 0.000 claims abstract description 61
- 239000000758 substrate Substances 0.000 claims abstract description 39
- 238000012544 monitoring process Methods 0.000 claims abstract description 35
- 229910052751 metal Inorganic materials 0.000 claims abstract description 29
- 239000002184 metal Substances 0.000 claims abstract description 29
- 239000000463 material Substances 0.000 claims description 20
- 238000005530 etching Methods 0.000 claims description 19
- 238000000034 method Methods 0.000 claims description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 9
- 238000004519 manufacturing process Methods 0.000 claims description 9
- 229910052814 silicon oxide Inorganic materials 0.000 claims description 9
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 8
- 229910052760 oxygen Inorganic materials 0.000 claims description 8
- 239000001301 oxygen Substances 0.000 claims description 8
- 239000003292 glue Substances 0.000 claims description 6
- 230000007704 transition Effects 0.000 claims description 5
- 238000000151 deposition Methods 0.000 claims description 4
- 230000008020 evaporation Effects 0.000 claims description 4
- 238000001704 evaporation Methods 0.000 claims description 4
- UMIVXZPTRXBADB-UHFFFAOYSA-N benzocyclobutene Chemical compound C1=CC=C2CCC2=C1 UMIVXZPTRXBADB-UHFFFAOYSA-N 0.000 claims description 3
- 230000000149 penetrating effect Effects 0.000 claims description 3
- 230000000694 effects Effects 0.000 abstract description 5
- 230000002411 adverse Effects 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 6
- 238000000206 photolithography Methods 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 3
- 238000001514 detection method Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 239000012530 fluid Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000005229 chemical vapour deposition Methods 0.000 description 1
- 238000005566 electron beam evaporation Methods 0.000 description 1
- 238000010894 electron beam technology Methods 0.000 description 1
- 238000009713 electroplating Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000010884 ion-beam technique Methods 0.000 description 1
- 230000001678 irradiating effect Effects 0.000 description 1
- 238000001755 magnetron sputter deposition Methods 0.000 description 1
- 238000001259 photo etching Methods 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 238000001020 plasma etching Methods 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/08—Mirrors
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/08—Mirrors
- G02B5/0816—Multilayer mirrors, i.e. having two or more reflecting layers
- G02B5/085—Multilayer mirrors, i.e. having two or more reflecting layers at least one of the reflecting layers comprising metal
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/13—Integrated optical circuits characterised by the manufacturing method
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/13—Integrated optical circuits characterised by the manufacturing method
- G02B6/132—Integrated optical circuits characterised by the manufacturing method by deposition of thin films
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12035—Materials
- G02B2006/1204—Lithium niobate (LiNbO3)
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12083—Constructional arrangements
- G02B2006/12104—Mirror; Reflectors or the like
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12133—Functions
- G02B2006/12147—Coupler
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B2006/12166—Manufacturing methods
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Optical Integrated Circuits (AREA)
Abstract
The invention discloses a vertical optical coupling device based on a thin film lithium niobate waveguide and a preparation method thereof, wherein the device comprises a substrate, a lithium niobate waveguide structure, a cladding, a metal reflector structure, a bonding layer and a photoelectric monitoring detector, wherein the lithium niobate waveguide structure comprises a lithium niobate waveguide and an oxygen-buried layer; the lithium niobate waveguide structure and the cladding are provided with an inclined plane opening structure with an opening facing the photoelectric monitoring detector, the inclined plane opening structure penetrates through the cladding and is embedded into an oxygen-buried layer with a preset depth, and the side surface of the inclined plane opening structure forms an included angle with the light receiving surface of the photoelectric monitoring detector; the metal reflector structure is arranged on the side surface of the inclined plane opening structure relative to the incident light direction of the lithium niobate waveguide; the metal mirror structure is used for reflecting incident light and absorbing stray light in the oxygen-buried layer. The embodiment of the invention reduces the adverse effect of stray light on the detector, widens the bandwidth of the coupler, and can be widely applied to the field of optical devices.
Description
Technical Field
The invention relates to the field of optical devices, in particular to a vertical optical coupling device based on a thin film lithium niobate waveguide and a preparation method thereof.
Background
Lithium niobate has excellent physical properties, has a large thermoelectric coefficient, piezoelectric coefficient, electro-optic coefficient and photoelastic coefficient, and is widely used in various integrated photonic devices. The optical coupling technology currently used on lithium niobate mainly includes a grating coupling technology of vertical coupling and an end-face coupling technology of parallel coupling. When the vertical coupling is implemented by using grating coupling, the problems of small wavelength bandwidth (40 nm-50 nm) and influence of stray light on signal detection are encountered. These problems are determined by the structure of the grating coupler, since the principle of the grating coupler is to couple an optical signal from one waveguide into another waveguide by using the diffraction effect of light; therefore, at different wavelengths, the corresponding diffraction angles and diffraction efficiencies are greatly different, resulting in a smaller bandwidth of the grating coupler. The stray light affects signal detection, and is because in practical application, a large amount of stray light caused by the laser coupler exists in the buried layer of the chip, and the stray light is radiated into the detector by the grating coupler when the stray light is in disordered transmission in the buried layer, so that detection and analysis of a real signal are affected.
Disclosure of Invention
In view of the above, an object of the embodiments of the present invention is to provide a vertical optical coupling device of a thin film lithium niobate waveguide and a method for manufacturing the same, which reduces adverse effects of stray light on a detector and widens the bandwidth of the coupler.
In a first aspect, an embodiment of the present invention provides a vertical optical coupling device based on a thin film lithium niobate waveguide, where the device includes a substrate, a lithium niobate waveguide structure, a cladding layer, a metal mirror structure, a bonding layer, and a photoelectric monitoring detector; the lithium niobate waveguide structure comprises a lithium niobate waveguide and an oxygen-buried layer, wherein the lithium niobate waveguide structure is arranged on the substrate, and the lithium niobate waveguide is arranged on the oxygen-buried layer; the cladding is arranged on the lithium niobate waveguide structure; the lithium niobate waveguide structure and the cladding are provided with an inclined plane opening structure with an opening facing the photoelectric monitoring detector, the inclined plane opening structure penetrates through the cladding and is embedded into an oxygen-buried layer with a preset depth, and the side surface of the inclined plane opening structure forms an included angle with the light receiving surface of the photoelectric monitoring detector; the metal reflector structure is arranged on the side surface of the inclined plane opening structure relative to the incident light direction of the lithium niobate waveguide; the bonding layer is filled in the inclined plane opening structure and covers the cladding; the photoelectric monitoring detector is arranged on the cladding; wherein,
a substrate for providing support for the device;
a lithium niobate waveguide for transmitting incident light;
a cladding layer for use as a transition layer to render the lithium niobate waveguide compatible with the bonding layer;
the metal reflector structure is used for reflecting incident light and absorbing stray light in the oxygen-buried layer;
the bonding layer is used for connecting and fixing the photoelectric monitoring detector with the cladding, a part below the cladding and an inclined plane opening structure;
and the photoelectric monitoring detector is used for receiving and transmitting the optical signal.
Optionally, the length of the lithium niobate waveguide is shorter than the buried oxide layer, one end of the lithium niobate waveguide is aligned with one end of the buried oxide layer, and an output end of the lithium niobate waveguide is spaced from a side surface of the inclined plane opening structure by a predetermined distance.
Optionally, the preset angle ranges from 30 ° to 60 °.
Optionally, the material of the bonding layer includes an ultraviolet light curing glue, and the ultraviolet light curing glue includes benzocyclobutene.
Optionally, the material of the buried oxide layer includes silicon oxide.
Optionally, the material of the cladding comprises silicon oxide.
In a second aspect, an embodiment of the present invention provides a method for manufacturing a vertical optical coupling device based on a thin film lithium niobate waveguide, including:
pretreating a substrate;
preparing a lithium niobate waveguide structure on the pretreated substrate, wherein the lithium niobate waveguide structure comprises a lithium niobate waveguide and an oxygen-buried layer;
preparing a cladding layer on the lithium niobate waveguide structure;
etching the cladding layer and the oxygen-buried layer in sequence to form an inclined plane opening structure;
preparing a metal reflector structure at a preset position of the side surface of the inclined plane opening structure;
filling a bonding layer in the inclined plane opening structure and covering the bonding layer on the cladding;
the photoelectric monitoring detector is arranged on the bonding layer and fixed on the bonding layer.
Optionally, preparing a lithium niobate waveguide structure on a substrate, specifically including:
depositing a buried oxide layer on a substrate;
and a lithium niobate waveguide is arranged on the oxygen-buried layer.
Optionally, preparing a metal reflector structure at a preset position on a side surface of the bevel opening structure, specifically including:
and preparing the metal reflector structure at a preset position of the side surface of the inclined plane opening structure in an evaporation mode.
Optionally, etching the cladding layer and the oxygen-buried layer sequentially to form an inclined plane opening structure specifically includes:
etching the cladding and penetrating the cladding;
etching a preset part of the buried oxide layer to form an inclined plane opening structure; the thickness of the preset part is smaller than that of the buried oxide layer.
The embodiment of the invention has the following beneficial effects: the vertical optical coupling device based on the thin film lithium niobate waveguide is provided with the inclined plane opening structure, and the inclined plane on one side of the inclined plane opening structure is provided with the metal reflecting mirror structure for reflecting incident light into the photoelectric monitoring detector; and the metal reflector structure is made of metal, and can absorb stray light which is randomly transmitted in the oxygen burying layer, so that adverse effects of the stray light on the photoelectric monitoring detector are reduced.
Drawings
FIG. 1 is a schematic diagram of a vertical optical coupling device based on a thin film lithium niobate waveguide according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of an optical path of a vertical optical coupling device based on a thin film lithium niobate waveguide according to an embodiment of the present invention;
FIG. 3 is a schematic flow chart of steps of a method for fabricating a vertical optical coupling device based on a thin film lithium niobate waveguide according to an embodiment of the present invention;
fig. 4 is a schematic structural diagram of a structure of a lithium niobate waveguide prepared on a substrate of a vertical optical coupling device based on a thin film lithium niobate waveguide according to an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a vertical optical coupling device based on a thin film lithium niobate waveguide according to an embodiment of the present invention, in which a cladding layer is prepared on a lithium niobate waveguide structure;
FIG. 6 is a schematic structural diagram of a slant opening structure obtained by preparing a vertical optical coupling device based on a thin film lithium niobate waveguide according to an embodiment of the present invention;
fig. 7 is a schematic structural diagram of a metal mirror structure prepared at a preset position on a side surface of an inclined plane opening structure of a vertical optical coupling device based on a thin film lithium niobate waveguide according to an embodiment of the present invention.
Detailed Description
The invention will now be described in further detail with reference to the drawings and to specific examples. The step numbers in the following embodiments are set for convenience of illustration only, and the order between the steps is not limited in any way, and the execution order of the steps in the embodiments may be adaptively adjusted according to the understanding of those skilled in the art.
In the following description, reference is made to "some embodiments" which describe a subset of all possible embodiments, but it is to be understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with one another without conflict.
In the following description, the terms "first", "second", "third" and the like are merely used to distinguish similar objects and do not represent a specific ordering of the objects, it being understood that the "first", "second", "third" may be interchanged with a specific order or sequence, as permitted, to enable embodiments of the invention described herein to be practiced otherwise than as illustrated or described herein.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the embodiments of the invention is for the purpose of describing embodiments of the invention only and is not intended to be limiting of the invention.
Before describing embodiments of the present invention in further detail, the terms and terminology involved in the embodiments of the present invention will be described, and the terms and terminology involved in the embodiments of the present invention will be used in the following explanation.
As shown in fig. 1, an embodiment of the present invention provides a vertical optical coupling device based on a thin film lithium niobate waveguide, the device including a substrate 1, a lithium niobate waveguide structure 2, a cladding layer 5, a metal mirror structure 6, a bonding layer 7, and a photoelectric monitoring detector 8; the lithium niobate waveguide structure 2 is arranged on the substrate 1, the lithium niobate waveguide structure 2 comprises a lithium niobate waveguide 3 and an oxygen-buried layer 4, and the lithium niobate waveguide 3 is arranged on the oxygen-buried layer 4; the cladding 5 is arranged on the lithium niobate waveguide structure 2; the lithium niobate waveguide structure 2 and the cladding 5 are provided with inclined plane opening structures with openings facing the photoelectric monitoring detector 8, the inclined plane opening structures penetrate through the cladding and are embedded into the oxygen burying layer 4 with preset depth, and the side surfaces of the inclined plane opening structures form included angles with the light receiving surface of the photoelectric monitoring detector 8; the metal mirror structure 6 is arranged on the side surface of the inclined plane opening structure relative to the incident light direction of the lithium niobate waveguide 3; the bonding layer 7 is filled in the inclined plane opening structure and covers the cladding 5; the photoelectric monitoring detector 8 is arranged on the cladding 5; wherein,
a substrate 1 for providing support for the device;
a lithium niobate waveguide 2 for transmitting incident light;
a cladding layer 5 for use as a transition layer to render the lithium niobate waveguide 3 compatible with the bonding layer 7;
a metal mirror structure 6 for reflecting incident light and absorbing stray light in the buried oxide layer 4;
the bonding layer 7 is used for connecting and fixing the photoelectric monitoring detector 8 with the cladding 5, the part below the cladding 5 and the inclined plane opening structure;
and the photoelectric monitoring detector 8 is used for receiving and transmitting the optical signals.
Specifically, as shown in fig. 2, light enters from the input end of the lithium niobate waveguide 3, passes through the lithium niobate waveguide 3 and the oxygen buried layer 4, exits from the inclined surface of the near lithium niobate waveguide 3 of the inclined surface opening structure, reaches the side surface of the inclined surface opening structure opposite to the incident light, and is reflected into the light receiving surface of the photoelectric monitoring detector 8, and the direction of the reflected light is perpendicular to the direction of the incident light and the light receiving surface of the photoelectric monitoring detector 8.
Specifically, the material of the substrate 1 includes, but is not limited to, silicon, and the specific material is determined according to practical situations, and is not limited in the embodiments of the present invention, and only examples are provided for reference, for example, the substrate 1 may be a silicon substrate.
Specifically, the bottom end of the inclined plane opening structure may be separated by a first preset distance, where the first preset distance is determined according to the actual situation, which is not limited in the embodiment of the present invention.
Optionally, the length of the lithium niobate waveguide 3 is shorter than the buried oxide layer 4, one end of the lithium niobate waveguide 3 is aligned with one end of the buried oxide layer 4, and the output end of the lithium niobate waveguide 3 is spaced from the side surface of the inclined plane opening structure by a predetermined distance.
Specifically, since etching is required in the cladding layer 5 and the oxygen-buried layer 4 to form the inclined plane opening structure, the lithium niobate waveguide 3 need not cover the entire oxygen-buried layer 4, and need only be provided on one side of the inclined plane opening structure.
Specifically, the output end of the lithium niobate waveguide 3 is separated from the side surface of the inclined plane opening structure by a second preset distance, and the second preset distance is determined according to the actual situation, which is not limited in the embodiment of the present invention.
Optionally, the preset angle ranges from 30 ° to 60 °.
Specifically, the preset angle is determined according to the actual situation, and the embodiment of the present invention is not limited, but only provides an embodiment for reference, for example, the preset angle is determined according to the lithium niobate waveguide structure, the inclined plane opening structure, the vertical distance between the incident light and the light receiving surface of the photoelectric monitoring detector 8, and the like, so that the incident light can be vertically reflected into the light receiving surface of the photoelectric monitoring detector 8.
Optionally, the material of the bonding layer 7 includes an ultraviolet light curing glue, and the ultraviolet light curing glue includes benzocyclobutene.
Specifically, the material of the bonding layer 7 may be converted from a fluid to a solid to function, for example, the ultraviolet curing adhesive needs to be converted from a fluid to a solid by an ultraviolet irradiation; and the material of the bonding layer 7, such as ultraviolet light curing glue, has the advantages of room temperature curing, high curing speed, safe and environment-friendly components and the like.
Alternatively, the material of the buried oxide layer 4 includes silicon oxide.
Specifically, since the refractive index of the material of the substrate is larger, light in the waveguide is easy to refract into the substrate, more loss and unnecessary stray light are generated, and therefore the oxygen burying layer 4 is arranged between the lithium niobate waveguide 3 and the substrate 1, the refractive index of the oxygen burying layer 4 is smaller than that of the substrate 1, and the probability that light in the lithium niobate waveguide 3 refracts into the substrate can be effectively reduced.
Specifically, the material of the oxygen-buried layer 4 includes, but is not limited to, silicon oxide, and the specific material is determined according to practical situations, and the embodiment of the present invention is not limited and is provided for reference only; in addition, the refractive index of the material of the buried oxide layer 4 needs to be smaller than that of the material of the substrate 1, for example, the refractive index of silicon oxide is much smaller than that of silicon.
Optionally, the material of the cladding 5 comprises silicon oxide.
Specifically, the cladding layer 5 plays a role in transition, and is used for enabling the lithium niobate waveguide structure 2 to be connected with the bonding layer 7 through the cladding layer 5, and taking the cladding layer 5 as a transition layer, so that the lithium niobate waveguide 3 is not in direct contact with the bonding layer 7, thereby affecting the transmission of light in the waveguide, and the lithium niobate waveguide 3 is compatible with the bonding layer 7; the material of the cladding 5 is determined according to practical situations, but the embodiment of the present invention is not limited thereto, and only examples are provided for reference, for example, the material of the cladding 5 may be silicon oxide.
The embodiment of the invention has the following beneficial effects: the vertical optical coupling device based on the thin film lithium niobate waveguide is provided with the inclined plane opening structure, and the inclined plane on one side of the inclined plane opening structure is provided with the metal reflecting mirror structure for reflecting incident light into the photoelectric monitoring detector; and the metal reflector structure is made of metal, and can absorb stray light which is randomly transmitted in the oxygen burying layer, so that adverse effects of the stray light on the photoelectric monitoring detector are reduced.
As shown in fig. 3, an embodiment of the present invention provides a method for manufacturing a vertical optical coupling device based on a thin film lithium niobate waveguide, including:
s100: pretreating a substrate;
s200: preparing a lithium niobate waveguide structure on the pretreated substrate, wherein the lithium niobate waveguide structure comprises a lithium niobate waveguide and an oxygen-buried layer;
s300: preparing a cladding layer on the lithium niobate waveguide structure;
s400: etching the cladding layer and the oxygen-buried layer in sequence to form an inclined plane opening structure;
s500: preparing a metal reflector structure at a preset position of the side surface of the inclined plane opening structure;
s600: filling a bonding layer in the inclined plane opening structure and covering the bonding layer on the cladding;
s700: the photoelectric monitoring detector is arranged on the bonding layer and fixed on the bonding layer.
Specifically, the connection between the substrate, the lithium niobate waveguide structure and the cladding layer may be implemented by a photolithography method, and the photolithography method includes, but is not limited to, any one of photolithography using a stepper, photolithography using a contact-type photoetching machine, electron beam direct writing or laser direct writing, and the like.
Specifically, the pretreatment of the substrate includes:
s101: preparing a substrate of a desired size;
s102: the surface of the substrate is cleaned to remove impurities.
Specifically, disposing and fixing a photo monitor probe on and to a bonding layer includes: and placing the photoelectric monitoring detector on the bonding layer, irradiating the bonding layer for a preset time by using an ultraviolet lamp to solidify the bonding layer, and fixing the photoelectric monitoring detector on the bonding layer after the bonding layer is solidified.
Alternatively, as shown in fig. 4, the lithium niobate waveguide structure 2 is prepared on a substrate, specifically including:
s201: depositing a buried oxide layer 4 on a substrate;
s202: a lithium niobate waveguide 3 is provided on the oxygen-buried layer 4.
In particular, methods of depositing buried oxide layer 4 on a substrate include, but are not limited to, coupled-ion chemical vapor deposition.
Specifically, the preparation of the lithium niobate waveguide structure 2 on the substrate may further include: the prepared lithium niobate waveguide structure 2 is purchased, the waveguide structure comprises an oxygen-buried layer 4 and a lithium niobate waveguide 3, and the prepared lithium niobate waveguide structure 2 is arranged on a substrate 1 and fixed.
Specifically, as shown in fig. 5, a cladding layer 5 is prepared on a lithium niobate waveguide structure.
Optionally, as shown in fig. 6, etching is sequentially performed on the cladding layer 5 and the oxygen-buried layer 4 to form a bevel opening structure, which specifically includes:
s401: etching the cladding 5 and penetrating the cladding 5;
s402: etching a preset part of the buried oxide layer 4 to form an inclined plane opening structure; the thickness of the preset portion is smaller than the thickness of the buried oxide layer 4.
Specifically, the etching manner includes, but is not limited to, any one of focused ion beam etching or reactive ion etching, and the specific manner is determined according to practical situations, and the embodiment of the invention is not limited.
Specifically, etching is performed on a preset part of the buried oxide layer 4, wherein the etching depth does not exceed the thickness of the buried oxide layer, namely, the etching of the buried oxide layer 4 does not penetrate through the buried oxide layer 4; the depth of etching the buried oxide layer 4 is determined according to practical situations, and is not limited in the embodiment of the invention.
Optionally, as shown in fig. 7, the metal mirror structure 6 is prepared at a preset position on the side surface of the bevel opening structure, and specifically includes:
s501: the metal mirror structure 6 is prepared by means of evaporation at a predetermined position of the side face of the bevel opening structure.
Specifically, the preset position is a side surface of the inclined plane opening structure relative to the incident light direction; in addition, the preset position can also comprise part or all of the bottom of the inclined plane opening structure or part of the cladding according to the specific situation of preparing the metal reflector structure.
Specifically, the evaporation mode includes, but is not limited to, any one of magnetron sputtering, electron beam evaporation, electroplating, etc., and the specific mode is determined according to the actual situation, which is not limited in the embodiment of the present invention.
It can be seen that the foregoing method embodiments are applicable to the method embodiments, and the functions specifically implemented by the method embodiments are the same as those of the device embodiments, and the beneficial effects achieved by the method embodiments are the same as those achieved by the device embodiments.
While the preferred embodiment of the present invention has been described in detail, the invention is not limited to the embodiment, and various equivalent modifications and substitutions can be made by those skilled in the art without departing from the spirit of the invention, and these modifications and substitutions are intended to be included in the scope of the present invention as defined in the appended claims.
Claims (10)
1. A vertical optical coupling device based on a thin film lithium niobate waveguide, which is characterized by comprising a substrate, a lithium niobate waveguide structure, a cladding layer, a metal reflector structure, a bonding layer and a photoelectric monitoring detector; the lithium niobate waveguide structure is arranged on the substrate and comprises a lithium niobate waveguide and an oxygen-buried layer, and the lithium niobate waveguide is arranged on the oxygen-buried layer; the cladding layer is arranged on the lithium niobate waveguide structure; the lithium niobate waveguide structure and the cladding are provided with an inclined plane opening structure with an opening facing the photoelectric monitoring detector, the inclined plane opening structure penetrates through the cladding and is embedded into the oxygen buried layer with a preset depth, and the side surface of the inclined plane opening structure forms an included angle with the light receiving surface of the photoelectric monitoring detector; the metal reflector structure is arranged on the side surface of the inclined plane opening structure relative to the incident light direction of the lithium niobate waveguide; the bonding layer is filled in the inclined plane opening structure and covers the cladding; the photoelectric monitoring detector is arranged on the cladding; wherein,
the substrate is used for providing support for the device;
the lithium niobate waveguide is used for transmitting incident light;
the cladding layer is used as a transition layer, so that the lithium niobate waveguide is compatible with the bonding layer;
the metal reflector structure is used for reflecting incident light and absorbing stray light in the oxygen-buried layer;
the bonding layer is used for connecting and fixing the photoelectric monitoring detector with the cladding, a part below the cladding and the inclined plane opening structure;
the photoelectric monitoring detector is used for receiving and transmitting optical signals.
2. The thin film lithium niobate waveguide-based vertical optical coupling device of claim 1, wherein the length of the lithium niobate waveguide is shorter than the buried oxide layer, one end of the lithium niobate waveguide is aligned with one end of the buried oxide layer, and an output end of the lithium niobate waveguide is spaced from a side of the bevel opening structure by a predetermined distance.
3. The thin film lithium niobate waveguide-based vertical optical coupling device of claim 1, wherein the predetermined angle ranges from 30 ° to 60 °.
4. The thin film lithium niobate waveguide-based vertical optical coupling device of claim 1, wherein the material of the bonding layer comprises an ultraviolet light curable glue comprising benzocyclobutene.
5. The thin film lithium niobate waveguide-based vertical optical coupling device of claim 1, wherein the material of the buried oxide layer comprises silicon oxide.
6. The thin film lithium niobate waveguide-based vertical optical coupling device of claim 1, wherein the material of the cladding layer comprises silicon oxide.
7. A method of fabricating a thin film lithium niobate waveguide-based vertical optical coupling device, comprising:
pretreating a substrate;
preparing a lithium niobate waveguide structure on the pretreated substrate, wherein the lithium niobate waveguide structure comprises a lithium niobate waveguide and an oxygen-buried layer;
preparing a cladding layer on the lithium niobate waveguide structure;
etching the cladding layer and the oxygen-buried layer in sequence to form an inclined plane opening structure;
preparing a metal reflector structure at a preset position of the side surface of the inclined plane opening structure;
filling a bonding layer in the inclined plane opening structure and covering the bonding layer on the cladding;
and arranging a photoelectric monitoring detector on the bonding layer and fixing the photoelectric monitoring detector on the bonding layer.
8. The method for manufacturing a vertical optical coupling device based on a thin film lithium niobate waveguide according to claim 7, wherein the manufacturing a lithium niobate waveguide structure on the substrate specifically comprises:
depositing a buried oxide layer on the substrate;
and setting a lithium niobate waveguide on the oxygen-buried layer.
9. The method for manufacturing a vertical optical coupling device based on a thin film lithium niobate waveguide according to claim 7, wherein the manufacturing a metal mirror structure at a predetermined position of a side surface of the inclined plane opening structure specifically comprises:
and preparing the metal reflector structure at a preset position of the side surface of the inclined plane opening structure in an evaporation mode.
10. The method for manufacturing a vertical optical coupling device based on a thin film lithium niobate waveguide according to claim 7, wherein the etching the cladding layer and the buried oxide layer sequentially to form a bevel opening structure specifically comprises:
etching the cladding and penetrating the cladding;
etching a preset part of the oxygen burying layer to form the inclined plane opening structure; the thickness of the preset part is smaller than that of the oxygen-buried layer.
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| CN202311296629.0A CN117348160A (en) | 2023-10-08 | 2023-10-08 | Vertical optical coupling device based on thin film lithium niobate waveguide and preparation method thereof |
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