CN116699761A - Mode multiplexing/demultiplexing device based on D-type optical fiber - Google Patents
Mode multiplexing/demultiplexing device based on D-type optical fiber Download PDFInfo
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- CN116699761A CN116699761A CN202310605504.5A CN202310605504A CN116699761A CN 116699761 A CN116699761 A CN 116699761A CN 202310605504 A CN202310605504 A CN 202310605504A CN 116699761 A CN116699761 A CN 116699761A
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- 239000013307 optical fiber Substances 0.000 title claims abstract description 117
- 238000006243 chemical reaction Methods 0.000 claims abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 7
- 230000008569 process Effects 0.000 claims abstract description 6
- 230000003287 optical effect Effects 0.000 claims abstract description 5
- 230000005540 biological transmission Effects 0.000 claims description 11
- 230000010287 polarization Effects 0.000 claims description 6
- 238000005253 cladding Methods 0.000 claims description 4
- 239000000835 fiber Substances 0.000 abstract description 19
- 238000003780 insertion Methods 0.000 abstract description 7
- 230000037431 insertion Effects 0.000 abstract description 7
- 238000004891 communication Methods 0.000 abstract description 6
- 230000033228 biological regulation Effects 0.000 abstract description 2
- 238000002844 melting Methods 0.000 abstract 2
- 230000008018 melting Effects 0.000 abstract 2
- 230000008878 coupling Effects 0.000 description 13
- 238000010168 coupling process Methods 0.000 description 13
- 238000005859 coupling reaction Methods 0.000 description 13
- 238000010586 diagram Methods 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 230000007704 transition Effects 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
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/14—Mode converters
-
- 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
- G02B2006/12152—Mode converter
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Integrated Circuits (AREA)
- Optical Couplings Of Light Guides (AREA)
- Optical Communication System (AREA)
Abstract
The invention discloses a mode multiplexing/demultiplexing device based on D-type optical fibers, which utilizes two D-type optical fibers to attach to the side planes of the two D-type optical fibers to form a mode selection coupler for realizing mode conversion, and then connects a plurality of mode selection couplers corresponding to different high-order modes in series to realize the function of multiplexing/demultiplexing the optical fiber modes. The D-type optical fiber reduces the fiber core distance between two optical fibers, and avoids the problems of insertion loss and sharp increase of inter-mode crosstalk caused by the steps of melting and tapering of few-mode optical fibers and changing the fiber core structure size of the optical fibers in the process of melting and tapering. The mode multiplexing/de-multiplexing device provided by the invention can effectively expand the multiplexing number of the optical fiber modes on the premise of ensuring low crosstalk and low insertion loss, and is applied to the fields of optical fiber communication, optical mode regulation and control and the like.
Description
Technical Field
The invention belongs to the technical field of optical fiber couplers, and particularly relates to a mode multiplexing/demultiplexing device based on a D-type optical fiber, which can be applied to the fields of optical fiber communication, optical mode regulation and control and the like.
Background
With the increasing demand for communication capacity, space division multiplexing is proposed to break through the transmission capacity bottleneck of single-mode optical fibers, following wavelength division multiplexing and polarization multiplexing. In the prior art, the mode multiplexer based on free space light has the advantages of large mode coupling insertion loss, high device cost, difficult integration, compatibility with an optical fiber system, compact structure and the like, and has great potential in communication application without Multiple Input Multiple Output (MIMO) -digital signal processing. At present, two technical schemes are widely adopted for all-fiber mode multiplexers, one is to melt and draw a plurality of single-mode fibers into a photon lantern to realize the multiplexing of a plurality of modes, and the manufacturing process is difficult. And the second mode is to manufacture a mode multiplexer by cascading a plurality of fusion tapered mode selection couplers on the few-mode optical fibers. Both the two technical schemes need to taper the transmission optical fiber in the coupling area, and due to the deformation of the fiber core and the coupling interference of the transition area, the adiabatic evolution condition of the higher-order mode is more strict, the insertion loss and the intermodal crosstalk are increased sharply along with the increase of the multiplexing order, and the communication quality is seriously reduced. Crosstalk and insertion loss serve as two important indicators of the multiplexer, and the performance of the fused-taper coupler in this respect limits the performance of its higher-order multiplexing, resulting in the limitation of existing all-fiber mode multiplexers to lower orders.
Disclosure of Invention
In order to solve the above problems in the prior art and adapt to the communication requirements, a mode multiplexer/demultiplexer based on D-type optical fiber is provided, which can effectively expand the number of optical fiber mode multiplexing on the premise of ensuring low crosstalk and low insertion loss.
The invention adopts the following technical scheme for realizing the purposes:
a D-type fiber based mode multiplexer/demultiplexer comprising the steps of: the mode conversion is realized by using the mode selection couplers formed by the side planes of the two D-shaped optical fibers in a bonding way, and then a plurality of mode selection couplers corresponding to different high-order modes are connected in series to realize the function of multiplexing/demultiplexing the optical fiber modes.
Preferably, one of the two D-type optical fibers is a few-mode optical fiber, and is a transmission optical fiber for transmitting a plurality of higher-order modes simultaneously; the other is a single-mode optical fiber or a few-mode optical fiber, which is an uploading/downloading optical fiber and is used for inputting/outputting a basic mode or a high-order mode.
Preferably, the D-shaped optical fiber is an optical fiber with a similar cross section to that of the D-shaped optical fiber, and the side part cladding is removed, and the fiber core structure is kept unchanged.
Preferably, the side plane fitting refers to that the side planes of the two D-shaped optical fibers, from which the cladding is removed, are aligned and tightly fitted, and the original fiber core shapes of the two D-shaped optical fibers are not changed.
Preferably, the mode conversion of the mode selection coupler means that after a fundamental mode or a higher-order mode in one uploading/downloading optical fiber and a higher-order mode of the other transmission optical fiber reach a phase matching condition, energy conversion is carried out between the fundamental mode or the higher-order mode and the higher-order mode of the other transmission optical fiber.
Preferably, the higher order modes include a column vector mode, a linear polarization mode, and an orbital angular momentum mode.
Preferably, the mode selection couplers are connected in series, that is, the transmission optical fibers of the couplers are the same few-mode optical fibers, and all the couplers are connected in sequence to upload/download each order of high-order mode at least to the transmission optical fibers.
Preferably, the optical fiber mode multiplexing/demultiplexing function refers to inputting a fundamental mode or a higher order mode from an uploading optical fiber, transmitting a plurality of higher order modes in a transmitting optical fiber at the same time, and outputting an optical fiber mode from a downloading optical fiber.
Preferably, the optical fiber mode multiplexing/demultiplexing means that according to the optical path reversibility principle, the demultiplexing process is the inverse process of multiplexing, and each order mode selection coupler structure in the demultiplexer is identical to the multiplexer.
The invention has the beneficial effects that:
1. the mode selection coupler provided by the invention consists of two D-type optical fibers, so that the mode evolution in the optical fiber tapering process is avoided, and the effective refractive index and the mode field distribution of the transmitted modes are not greatly influenced because the fiber core structure of the few-mode optical fibers in the coupling area is not changed, so that the stability and the orthogonality of the modes are well maintained, and the inter-mode crosstalk and the coupling loss of the coupling area are effectively reduced.
2. The invention adopts a series structure, and the modes are mutually orthogonal due to different phase matching conditions of the mode selection couplers, so that the mode selection couplers in series do not have any influence.
3. The mode selection coupler structure provided by the invention has the advantages of higher mode order, shorter coupling length, lower manufacturing difficulty and unlimited mode coupling and multiplexing order.
Drawings
FIG. 1 is a schematic side view of a D-type optical fiber in which gray portions are cores.
Fig. 2 is a schematic side view of a mode selection coupler, with coupling regions within the dashed line portions.
Fig. 3 is a schematic cross-sectional view of a mode selection coupler.
Fig. 4 is a schematic diagram of a mode multiplexer/demultiplexer, which is composed of a plurality of mode selection couplers connected in series.
Fig. 5 is a schematic diagram of an optical fiber 1-3 order linear polarization mode multiplexer/demultiplexer according to an embodiment.
Reference numerals illustrate: 1-few-mode optical fiber; 2-a first single mode optical fiber; 3-a second single mode optical fiber; 4-a third single mode optical fiber.
Detailed Description
In order to more clearly reflect the technical problems to be solved by the present invention and the gist of a technical solution to solve the problems, the present invention will be described in further detail with reference to the following examples and the accompanying drawings.
As shown in figures 1-5, the mode multiplexing/demultiplexing device based on D-type optical fiber provided by the invention is characterized in that two D-type optical fibers meeting the requirement of equal refractive index of optical fiber modes are aligned and fused on the side planes of the two D-type optical fibers, the length of a coupling area is controlled so as to achieve a phase matching condition, a mode selection coupler for realizing mode conversion is formed, and a plurality of mode selection couplers corresponding to different high-order optical fiber modes are connected in series to realize the function of multiplexing/demultiplexing the optical fiber modes.
Embodiment 1 fig. 5 is a schematic diagram of a high order Linear Polarization (LP) mode multiplexer/demultiplexer of the present invention, which includes a few-mode optical fiber 1 and several optical fibersSingle mode optical fibers (a first single mode optical fiber 2, a second single mode optical fiber 3, and a third single mode optical fiber 4). And designing the base mode refractive index of the first single mode fiber to be equal to the LP11 mode refractive index of the few mode fiber, and preparing the few mode fiber and the single mode fiber into the D type fiber as shown in figure 1. As shown in fig. 2, the side planes of the two optical fibers are melted at high temperature to meet the core spacing condition required by coupling, and meanwhile, the length of the coupling, namely the length of the joint region of the two optical fibers, is controlled to realize the condition of phase matching. The cross-section of the bonded region of two fibers is shown in fig. 3. LP of single-mode optical fiber and few-mode optical fiber 11 Mode coupling, conversion of energy from fundamental mode to LP 11 Mode, i.e. the function of a mode selection coupler is achieved. LP for designing the fundamental refractive index and few-mode fiber of a second single-mode fiber 21 The mode refractive indexes are equal, and the few-mode optical fiber and the single-mode optical fiber are prepared into the D-type optical fiber. Similarly, the LP of the fundamental mode and the few-mode of the single-mode optical fiber is realized by the two optical fibers 21 The energy exchange between modes, i.e. the function of the mode selection coupler. While the LP due to the first mode-selective coupler 11 Fundamental mode, LP of mode and second mode selection coupler 21 The refractive indexes of the modes are unequal, and the modes are in an orthogonal relation, so that the mode selection couplers which are in series connection do not influence each other in theory, the fiber core structure of the few-mode optical fiber in the bonding area is unchanged, and therefore, the deformation of the modes or the crosstalk between the modes are not caused. According to the technical scheme, the inter-mode crosstalk and the insertion loss can be kept low, and meanwhile, the mode multiplexing order of the few-mode optical fiber can be continuously increased.
The technical scheme of the invention is not limited to the asymmetric mode selection coupler based on the single mode optical fiber and the few mode optical fiber in the embodiment 1, and the symmetric coupler can be manufactured by two identical few mode optical fibers. Other methods for exciting the high-order modes of the optical fiber, such as an optical fiber grating and the like, are adopted to realize the function of the mode selection coupler in a combined way.
Also, the optical fiber mode of the present invention is not limited to the linear polarization mode in example 1, and includes a range of other modes supported by the few-mode optical fiber such as the column vector mode and the orbital angular momentum mode.
The foregoing is illustrative of the present invention and its features and advantages. It will be understood by those skilled in the art that the present invention is not limited to the foregoing embodiments, and that the foregoing embodiments and description are merely illustrative of one implementation covered by the technical solution of the present invention, and that various changes and modifications may be made in the details without departing from the technical solution of the present invention, which changes and modifications fall within the scope of the claimed invention. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (9)
1. A D-type optical fiber based mode multiplexer/demultiplexer comprising the steps of: the mode conversion is realized by using the mode selection couplers formed by the side planes of the two D-shaped optical fibers in a bonding way, and then a plurality of mode selection couplers corresponding to different high-order modes are connected in series to realize the function of multiplexing/demultiplexing the optical fiber modes.
2. The D-type optical fiber based mode multiplexer/demultiplexer according to claim 1, wherein one of the two D-type optical fibers is a few-mode optical fiber, and is a transmission optical fiber for simultaneously transmitting a plurality of higher-order modes; the other is a single-mode optical fiber or a few-mode optical fiber, which is an uploading/downloading optical fiber and is used for inputting/outputting a basic mode or a high-order mode.
3. A D-type optical fiber-based mode multiplexer/demultiplexer according to claim 1, wherein the D-type optical fiber is a D-type optical fiber having a cross section similar to that of the D-type optical fiber by removing a side portion of the cladding layer and leaving a core structure unchanged.
4. A D-type optical fiber based mode multiplexer/demultiplexer according to claim 1, wherein the side plane fitting means that the side planes of the two D-type optical fibers from which the cladding is removed are first aligned and tightly fitted without changing the original core shapes of the two D-type optical fibers.
5. The D-type optical fiber-based mode multiplexer/demultiplexer according to claim 1, wherein the mode conversion performed by the mode selection coupler means that energy conversion is performed between a fundamental mode or a higher-order mode in one of the uploading/downloading optical fibers and a higher-order mode of the other transmission optical fiber after the two modes reach a phase matching condition.
6. A D-type optical fiber based mode multiplexer/demultiplexer according to claim 1, wherein the higher order modes comprise a column vector mode, a linear polarization mode and an orbital angular momentum mode.
7. The D-type optical fiber based mode multiplexer/demultiplexer according to claim 1, wherein the mode selection coupler is connected in series, that is, the transmission optical fiber of each coupler is the same few-mode optical fiber, and all the couplers are connected in sequence to upload/download each higher-order mode at least to the transmission optical fiber.
8. A D-type optical fiber-based mode multiplexer/demultiplexer according to claim 1, wherein the optical fiber mode multiplexing/demultiplexing function refers to inputting a fundamental mode or a higher order mode from an uploading optical fiber, transmitting a plurality of higher order modes in a transmitting optical fiber at the same time, and outputting an optical fiber mode from a downloading optical fiber.
9. The D-type optical fiber-based mode multiplexing/demultiplexing device according to claim 1, wherein the optical fiber mode multiplexing/demultiplexing means that the demultiplexing process is the inverse process of multiplexing according to the optical path reversibility principle, and each order mode selection coupler structure in the demultiplexer is identical to the multiplexer.
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202310605504.5A CN116699761A (en) | 2023-05-25 | 2023-05-25 | Mode multiplexing/demultiplexing device based on D-type optical fiber |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202310605504.5A CN116699761A (en) | 2023-05-25 | 2023-05-25 | Mode multiplexing/demultiplexing device based on D-type optical fiber |
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| CN202310605504.5A Pending CN116699761A (en) | 2023-05-25 | 2023-05-25 | Mode multiplexing/demultiplexing device based on D-type optical fiber |
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- 2023-05-25 CN CN202310605504.5A patent/CN116699761A/en active Pending
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