CN117518340A - Hollow optical fiber and laser beam coupler - Google Patents
Hollow optical fiber and laser beam coupler Download PDFInfo
- Publication number
- CN117518340A CN117518340A CN202311542454.7A CN202311542454A CN117518340A CN 117518340 A CN117518340 A CN 117518340A CN 202311542454 A CN202311542454 A CN 202311542454A CN 117518340 A CN117518340 A CN 117518340A
- Authority
- CN
- China
- Prior art keywords
- hollow
- core
- hollow fiber
- fiber
- cores
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000013307 optical fiber Substances 0.000 title claims description 59
- 239000012510 hollow fiber Substances 0.000 claims abstract description 101
- 238000005253 cladding Methods 0.000 claims abstract description 48
- 239000007787 solid Substances 0.000 claims abstract description 40
- 230000010287 polarization Effects 0.000 claims abstract description 32
- 239000004038 photonic crystal Substances 0.000 claims abstract description 17
- 239000000463 material Substances 0.000 claims description 8
- 239000000835 fiber Substances 0.000 abstract description 31
- 238000010168 coupling process Methods 0.000 abstract description 30
- 230000008878 coupling Effects 0.000 abstract description 28
- 238000005859 coupling reaction Methods 0.000 abstract description 28
- 239000006185 dispersion Substances 0.000 abstract description 6
- 230000008901 benefit Effects 0.000 abstract description 4
- 230000005540 biological transmission Effects 0.000 description 25
- 238000009826 distribution Methods 0.000 description 16
- 230000003287 optical effect Effects 0.000 description 10
- 230000002093 peripheral effect Effects 0.000 description 9
- 238000000034 method Methods 0.000 description 8
- 238000004891 communication Methods 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 230000008569 process Effects 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 239000011343 solid material Substances 0.000 description 3
- 230000000694 effects Effects 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000008054 signal transmission Effects 0.000 description 2
- 230000003595 spectral effect Effects 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000012546 transfer Methods 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 230000005672 electromagnetic field Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 230000010354 integration Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 230000031700 light absorption Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000000149 penetrating effect Effects 0.000 description 1
- 230000035699 permeability Effects 0.000 description 1
- 230000002787 reinforcement Effects 0.000 description 1
- 238000012827 research and development Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 230000001131 transforming effect Effects 0.000 description 1
- 238000000411 transmission spectrum Methods 0.000 description 1
Classifications
-
- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/032—Optical fibres with cladding with or without a coating with non solid core or cladding
-
- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02295—Microstructured optical fibre
-
- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02295—Microstructured optical fibre
- G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
- G02B6/02342—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by cladding features, i.e. light confining region
-
- 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
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/02295—Microstructured optical fibre
- G02B6/02314—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes
- G02B6/02342—Plurality of longitudinal structures extending along optical fibre axis, e.g. holes characterised by cladding features, i.e. light confining region
- G02B6/02361—Longitudinal structures forming multiple layers around the core, e.g. arranged in multiple rings with each ring having longitudinal elements at substantially the same radial distance from the core, having rotational symmetry about the fibre axis
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
Abstract
The application relates to a hollow fiber and a laser beam coupler, and belongs to the field of hollow photonic crystal fiber devices. Wherein, hollow optic fibre includes: a first hollow core; the second hollow fiber cores are arranged in a plurality, and the second hollow fiber cores are circumferentially distributed by taking the first hollow fiber core as a circle center; the second hollow fiber core is communicated with the first hollow fiber core through an air channel; the photonic crystal cladding is arranged on the outer side of each second hollow fiber core in a surrounding mode and comprises an inner cladding arranged on the outer side of each second hollow fiber core in a surrounding mode, and the inner cladding comprises a plurality of solid tubes; and an outer cladding layer wrapping the outer sides of the plurality of second hollow fiber cores; the first hollow fiber cores and the second hollow fiber cores are the same in size, and the polarization directions of the second hollow fiber cores are the same or different. By the mode, the laser beam coupler has the advantages of low loss, low dispersion and beam polarization maintaining, and can realize low-loss coupling with different hollow fibers, so that the hollow fibers are fused into an all-fiber system.
Description
[ field of technology ]
The application relates to a hollow fiber and a laser beam coupler, and belongs to the field of hollow photonic crystal fiber devices.
[ background Art ]
Since the advent of hollow-core photonic crystal fibers, the advantages of low transmission loss, low dispersion, low nonlinearity, etc. have attracted tremendous research and development investment and have made corresponding progress-the transmission loss of light in practical hollow-core fibers has been reduced to lower and lower, and by 2021 researchers have successfully achieved laser transmission with losses as low as 0.28dB/km around 1550nm wavelength. The hollow fiber can also be used as a carrier for realizing efficient interaction between light and substances, and is applied to various fields such as sensing, biomedical treatment, optical fiber communication and the like. In order to adapt hollow-core optical fibers with wider and more complete functions, the hollow-core optical fibers can be integrated into an all-optical fiber system, and the requirements for hollow-core optical fiber devices are also higher and higher. Various hollow fiber devices have been designed in the past, such as fiber filters, fiber couplers, and the like.
The optical fiber coupler plays an important role in the application fields of optical fiber sensing, optical fiber communication and the like. Especially in the field of optical fiber communication, the method can be used for increasing the number of channels, thereby greatly increasing the information capacity of a communication system. Conventional solid fiber couplers are difficult to achieve low loss fusion with hollow core photonic crystal fibers. In addition, many hollow fiber couplers have no hollow channels between the fiber cores, so that high coupling efficiency is difficult to realize, and the hollow fiber couplers have no more than three channels. In addition, if the polarization maintaining characteristic can be introduced into the optical fiber coupler, the communication noise and the error rate can be further reduced, and the method has important significance for improving the optical fiber communication quality.
Accordingly, there is a need for an improvement over the prior art to overcome the deficiencies described in the prior art.
[ invention ]
The purpose of this application is to provide a hollow optic fibre and can adapt this hollow optic fibre's laser beam coupler, and laser beam coupler both has low loss, low dispersion, the advantage of beam polarization maintaining, can realize the low loss coupling with between the hollow optic fibre of difference again to fuse hollow optic fibre into full optical fiber system.
The purpose of the application is realized through the following technical scheme: a hollow fiber for a laser beam coupler, the hollow fiber comprising:
a first hollow core;
the second hollow fiber cores are arranged in a plurality, and the second hollow fiber cores are circumferentially distributed by taking the first hollow fiber core as a circle center; the second hollow fiber core is communicated with the first hollow fiber core through an air channel;
the photonic crystal cladding is arranged on the outer side of each second hollow fiber core in a surrounding mode, the photonic crystal cladding comprises an inner cladding arranged on the outer side of each second hollow fiber core in a surrounding mode, and the inner cladding comprises a plurality of solid tubes; and
the outer cladding layers are wrapped on the outer sides of the photonic crystal cladding layers;
the first hollow fiber cores and the second hollow fiber cores are the same in size, and the polarization directions of the second hollow fiber cores are the same or different.
In one embodiment, the thickness of the solid tubes is the same, so that the polarization directions of the second hollow fiber cores are the same; or (b)
The thickness of a portion of the solid tube differs from the thickness of the remaining portion of the solid tube such that the polarization direction of the plurality of second hollow cores differs.
In one embodiment, the distance from the center of the first hollow core to the center of any one of the second hollow cores is 2-3 times the diameter of the first hollow core or the second hollow core.
In one embodiment, the inner cladding and the outer cladding are the same material.
In one embodiment, the plurality of solid tubes are circumferentially distributed with the second hollow fiber core as a center;
the structures of the solid pipes are the same; the thickness of each of the solid tubes ranges from 0.2 to 2 μm.
In one embodiment, the inner cladding surrounding the air channel is in a concave arc shape.
In one embodiment, the refractive index of the gas within the air channel is less than the refractive index of the material of the inner cladding or the outer cladding.
In one embodiment, the first hollow core has a first gas and the second hollow core has a second gas, the first gas having the same refractive index as the second gas.
In one embodiment, the refractive index of the gas in the air channel is equal to the refractive indices of the first gas and the second gas.
The application also provides a laser beam coupler comprising a hollow fiber as described above.
Compared with the prior art, the application has the following beneficial effects: the hollow optical fiber comprises a first hollow optical fiber and a plurality of second hollow optical fibers which are circumferentially distributed by taking the first hollow optical fiber as a center, and the second hollow optical fibers are communicated with the first hollow optical fibers through air channels, wherein the first hollow optical fibers are used as central channels, and the second hollow optical fibers are used as peripheral channels, so that a plurality of channels are integrated into one optical fiber structure, light beams among all channels can be coupled through gas in the hollow, uniform coupling of light energy among the central channels and the peripheral channels is ensured, light is prevented from being absorbed or scattered by solid materials, coupling efficiency is improved, and coupling loss is reduced; in addition, the structure can reduce the chromatic dispersion in the optical signal transmission process to the maximum extent and keep low transmission loss; meanwhile, the first hollow fiber core and the second hollow fiber core in the hollow fiber have the same size and structure, so that the uniform coupling of optical energy between a central channel and a peripheral channel is further ensured; in addition, by adjusting the thickness of the cladding structure solid tube, flexible polarization reinforcement of the polarization direction can be realized.
Notably, the air transport channels between the cores are of breakthrough significance for laser coupling. The invention ensures the production and processing friendliness of the optical fiber structure, and simultaneously makes the natural continuity of the fiber core and the air channel structure in space, so that the coupling of the light beam is fully free from the influence of solids, thereby realizing the air transmission in the optical fiber to the bottom, and enabling the real integration of the hollow optical fiber into the all-fiber system to be possible.
[ description of the drawings ]
FIG. 1a is a cross-sectional view of a hollow-core optical fiber of the present invention;
FIG. 1b is a partial cross-sectional view of a hollow-core optical fiber of the present invention;
FIG. 2 is a spectral diagram of transmissible within a hollow core fiber of the present invention;
FIG. 3 is a mode field distribution diagram of all lowest order supermodes in a hollow core fiber of the present invention, wherein each supermode corresponds to an optical field concentrated in a single core;
FIG. 4a is a cross-sectional view of three lines extending through the centers of a first hollow core and a second hollow core, respectively, with the line-end arrows indicating the direction of the cross-sectional view;
fig. 4b and 4c are graphs of the optical energy distribution of the lowest order supermodes within the hollow core fiber for laser beam coupling of the present invention, taking 2 of all the lowest order supermodes as an example: the lowest order supermodes where the optical field is concentrated in the central core and the lowest order supermodes where the optical field is concentrated in one of the peripheral cores, respectively;
FIG. 5 is another cross-sectional structural view of a hollow-core optical fiber of the present invention;
FIG. 6 is a schematic illustration of a structure in which the polarization direction of the second hollow core is uniform;
fig. 7 is a schematic diagram showing a structure in which the polarization directions of the second hollow cores are different.
[ detailed description ] of the invention
In order to make the above objects, features and advantages of the present application more comprehensible, embodiments accompanied with figures are described in detail below. It is to be understood that the specific embodiments described herein are for purposes of illustration only and are not limiting. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present application are shown in the drawings. All other embodiments, which can be made by one of ordinary skill in the art without undue burden from the present disclosure, are within the scope of the present disclosure.
The terms "comprising" and "having" and any variations thereof herein are intended to cover a non-exclusive inclusion. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus.
Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the present application. The appearances of such phrases in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. Those of skill in the art will explicitly and implicitly appreciate that the embodiments described herein may be combined with other embodiments.
Referring to fig. 1a to 4c, a hollow fiber according to a preferred embodiment of the present application is used in a laser beam coupler. The hollow fiber comprises a first hollow fiber core 1, a second hollow fiber core 2, a photonic crystal cladding layer and an outer cladding layer 5, wherein the second hollow fiber core 2 is provided with a plurality of second hollow fiber cores 2 which are circumferentially distributed by taking the first hollow fiber core 1 as the center of a circle and are communicated with the first hollow fiber core 1 through an air channel 3. And the photonic crystal cladding is enclosed outside each second hollow fiber core 2, and the outer cladding 5 is enclosed outside the photonic crystal cladding.
The cross-sectional shapes of the first hollow core 1 and the second hollow core 2 may be approximately circular, approximately elliptical, approximately square or approximately triangular, which are not particularly limited herein, and are according to practical situations. In the present embodiment, the cross-sectional shapes of the first hollow core 1 and the second hollow core 2 are described specifically as being nearly circular.
The total number of the fiber cores of the hollow optical fiber is 4-9. Wherein the first hollow fiber cores 1 are provided with one, and the number of the second hollow fiber cores 2 is 3-8. The greater the number of cores, the greater the number of channels representing hollow fiber, and the greater the system capacity. However, designing an excessive number of channels tends to increase the distance between the first hollow core 1 and the second hollow core 2 in the optical fiber geometry, thereby increasing the coupling difficulty. Therefore, in this embodiment, the number of the second hollow fiber cores 2 is 6, the 6 second hollow fiber cores 2 are circumferentially distributed with the first hollow fiber core 1 as a center, and the 6 second hollow fiber cores 2 are equidistantly arranged, so as to ensure uniform light coupling. And, in the embodiment, the first hollow core 1 and the second hollow core 2 have the same size, the uniform coupling degree of light in the hollow optical fiber is further improved.
In this embodiment, the cross-sectional structural characteristics of the hollow fiber are infinitely extended along the length of the hollow fiber, i.e., the structure of the hollow fiber maintains uniformity along the length of the fiber. Also, the diameter of the hollow fiber is sized depending on the laser wavelength to be transmitted, and if light of a long wavelength is transmitted, a larger-sized core is correspondingly designed, and vice versa. In this embodiment, the hollow fiber has a core diameter ranging from 15 μm to 50 μm, and transmits laser light with a wavelength ranging from 0.3 μm to 3.2 μm, so that the transmission of the laser light in each core can be ensured to be single-mode or low-order mode transmission, thereby ensuring relatively high output beam quality.
The first hollow fiber core 1 is used as a central channel, and the second hollow fiber core 2 is used as a peripheral channel, so that a plurality of channels can be integrated in one optical fiber structure, light beams among all channels can be coupled through gas in the hollow, uniform coupling of light energy between the central channel and the peripheral channel is ensured, light is prevented from being absorbed or scattered by solid materials, coupling efficiency is further improved, and coupling loss is reduced.
And, the distance from the center of the first hollow fiber core 1 to the center of any one of the second hollow fiber cores 2 is 2-3 times the diameter of the first hollow fiber core 1 or the second hollow fiber core 2. Within this range, low loss coupling up to 100% coupling efficiency can be achieved.
The first hollow core 1 has a first gas and the second hollow core 2 has a second gas, and the refractive index of the first gas is the same as that of the second gas. Meanwhile, the refractive index of the gas in the air passage 3 is equal to that of the first gas and the second gas, thereby reducing loss in light transmission.
And the photonic crystal cladding includes an inner cladding layer surrounding the outer side of the second hollow core 2, wherein the inner cladding layer and the outer cladding layer 5 are the same material. In this embodiment, the material of the inner cladding and the outer cladding 5 is quartz glass, and its refractive index is 1.45.
And, the refractive index of the gas in the air passage 3 is smaller than that of the material of the inner cladding or the outer cladding 5, thereby ensuring that light can be transmitted with low loss under the hollow antiresonant light transmission mechanism of the hollow fiber. From the foregoing, the refractive index of the outer cladding 5 or the inner cladding is 1.45, and the refractive index of the gas in the air passage 3 is less than 1.45.
The inner cladding comprises a plurality of solid tubes 4, and the solid tubes 4 are circumferentially distributed by taking the second hollow fiber core 2 as a center. The structure of the plurality of solid tubes 4 is the same, and the thickness of each solid tube 4 is in the range of 0.2-2 mu m. Within this range, the operating wavelength of the hollow fiber can be made to cover a plurality of wide bandwidths from 0.3 μm to 3 μm or more.
And the number of the solid pipes 4 is 5-8, so that the optical fiber processing difficulty is reduced as much as possible while low-loss transmission is ensured. Meanwhile, the inner cladding surrounding the outer side of the air channel 3 is in a concave arc shape. That is, the inner cladding layer surrounding the outside of the air channel 3 is arc-shaped with a negative curvature to reduce dispersion during transmission of the optical signal and maintain low transmission loss.
Meanwhile, the laser coupling and the light beam polarization maintaining are combined, so that the light beam polarization degree is enhanced, the error rate of the whole communication system caused by factors such as non-uniformity in the optical fiber, environmental influence, optical fiber fusion and the like is reduced, and flexible polarization enhancement of the polarization direction is realized. In order to achieve the above object, several second hollow cores 2 in the present application have the same or different polarization directions. The thickness of the solid tubes 4 is the same, so that the polarization directions of the second hollow fiber cores 2 are the same; or a part of the thickness of the solid tube 4 is different from the thickness of the remaining part of the solid tube 4 so that the polarization directions of the plurality of second hollow cores 2 are different. In a word, the distribution direction of the circular rings of each fiber core of the solid can be flexibly adjusted according to the actual light path, so that the effect of controlling the polarization state of the light beam is achieved.
It should be noted that the adjustment of the thickness of the solid tube 4 only changes the polarization state of the laser, and does not affect the light energy distribution in each fiber core.
From the foregoing, it can be seen that the cross-sectional structural characteristics of the hollow fiber are infinitely extended along the length of the hollow fiber, i.e., the structure of the hollow fiber maintains uniformity along the length of the fiber. While the wavelength λ at which light is resonated with the photonic crystal cladding and thus has high loss when transmitted in the respective cores (the first hollow core 1 and the second hollow core 2) of the hollow optical fiber in the direction of the optical fiber length is expressed as:
wherein t is the thickness of the solid tube 4, n is the refractive index of the solid tube 4, n 0 The refractive index of the first gas or the second gas, and m can be any positive integer. Thus, at lambda m Light can be transmitted with low loss in hollow fiber in other broad spectral regions than around the wavelength.
When the hollow optical fiber works, laser beams with certain wavelength are incident from one or a plurality of channels at the input end of the hollow optical fiber, and can be emitted from one or a plurality of channels at the output end of the hollow optical fiber after being transmitted by the hollow optical fiber with certain length, thereby achieving the aim of multi-beam coupling. The underlying principle is that the electromagnetic fields phase interfere with each other between the light beams transmitted in the different channels, so that the light exchanges energy between the channels during transmission along the hollow fiber, thereby transforming the channels. Referring to fig. 3, in this embodiment, the electric field distribution of the light in the hollow fiber during the transmission and coupling process can be expressed as:
wherein E is the electric field intensity distribution of the light wave, mu 0 For vacuum permeability, epsilon 0 For vacuum conductivity, r is the path of light transmission, t is the propagation time experienced by the light, and the polarization of the gas in the P first or second core varies with the disturbance caused by the coupled light waves.
When laser transmits in a certain fiber core, the vibration direction of the electric field of the laser is positively intersected with two fundamental mode polarization states LP 01_x And LP 01_y Is subjected to a thickness t in the x-direction around the core 1 And a thickness t in the y-direction 2 The solid ring of the solid layer is affected to make the superposition range of the fundamental mode field and the solid layer of two polarization states different, resulting in the coupling condition of the two fundamental modes and the cladding modeThe difference is generated, so that the effective refractive indexes of the two orthogonal polarization modes are different, and a polarization maintaining effect is generated.
The application also provides a laser beam coupler comprising the hollow fiber.
Specific examples will be described below.
In this embodiment, the diameter D of the first hollow core 1 and the second hollow core 2 is 30 μm, and the thickness t of each solid tube 4 is 0.6 μm; the solid tube 4 is made of quartz glass, and the refractive index n of the quartz glass is 1.45; the first hollow fiber core 1 and the second hollow fiber core 2 are filled with air, and the refractive index of the air is 1; the distance L between the first hollow fiber core 1 and any second hollow fiber core 2 is 70 mu m; the outer cladding 5 has a diameter of 250 μm.
Referring to fig. 2, fig. 2 is a spectrum of the transmission of the hollow fiber of the present invention. It can be seen that the hollow core optical fiber of the present invention allows for low loss transmission of light over a wide range of spectra. The first two high loss wavelengths in the transmission spectrum are 1260nm and 630nm, respectively, so the first transmission window, the widest transmission window, theoretically covers from 1260nm to infinitely long wavelengths. However, for a photonic crystal fiber in which the material of the solid tube 4 is quartz glass, the transmission window width is about 1500nm; the second transmission window, the next-to-wide transmission window, is 630-1260nm, and the width of the covered transmission window is about 600nm. The extremely wide transmission bandwidth greatly widens the application range and the application field of the coupler.
In the widely used theory of the coupling modes, the supermodes can be equivalent to the overall distribution of independent modes in each channel in the coupling process, and the number of the supermodes is consistent with the number of the channels, so that more convenient supermodes are generally used for carrying out mode analysis. Referring to fig. 3, fig. 3 shows the mode field distribution of all 7 lowest order supermodes. As can be seen from fig. 3, when light is incident on one of the 7 cores (first hollow core 1 and second hollow core 2), outputs of different cores (first hollow core 1 and second hollow core 2) are available at the output end of the hollow fiber, and it is possible to determine from which core (second hollow core 2) the light is output by selecting the length of the hollow fiber, i.e., the coupling distance the light undergoes in the hollow fiber.
Referring to fig. 4a, 4b and 4c, fig. 4a is a view showing three cross-sectional lines penetrating the centers of the first hollow core 1 and the second hollow core 2, respectively, and the line-end arrows indicate the cross-sectional line directions. Fig. 4b shows the light energy distribution along the three stubs in fig. 4a for the lowest order supermode in which the light field is concentrated in the first hollow core 1, and fig. 4c shows the light energy distribution along the three stubs in fig. 4a for the lowest order supermode in which the light field is concentrated in one of the second hollow cores 2. The light energy distribution of fig. 4c is taken as an example, and may represent any of the supermodes in fig. 4, where the position with the highest energy in the light energy distribution map is only required to correspond to the fiber core with concentrated light field distribution in the observed supermode.
Taking the two supermode optical energy distributions represented in fig. 4b and 4c, respectively, as an example, it is evident that light can be coupled to achieve a complete transfer of energy between the first hollow core 1 and either the second hollow core 2 with a transfer efficiency of approximately 100%. If other splitting ratios are required at the output end of the hollow fiber coupler, for example 50% and 50% or 20% and 80%, it is only necessary to select the appropriate fiber length within one coupling period length.
To sum up: the hollow optical fiber comprises a first hollow optical fiber and a plurality of second hollow optical fibers which are circumferentially distributed by taking the first hollow optical fiber as a center, and the second hollow optical fibers are communicated with the first hollow optical fibers through the air channel 3, wherein the first hollow optical fibers are used as central channels, and the second hollow optical fibers are used as peripheral channels, so that a plurality of channels are integrated into one optical fiber structure, light beams among all channels can be coupled through gas in the hollow, uniform coupling of light energy among the central channels and the peripheral channels is ensured, light absorption or scattering by solid materials is avoided, coupling efficiency is further improved, and coupling loss is reduced; in addition, the structure can reduce the chromatic dispersion in the optical signal transmission process to the maximum extent and keep low transmission loss; meanwhile, the first hollow fiber core 1 and the second hollow fiber core 2 in the hollow fiber have the same size and structure, so that the uniform coupling of the optical energy between the central channel and the peripheral channel is further ensured.
With respect to polarization maintaining functionTaking fig. 5 as an example, the thickness t of the 4 solid tubes 4 in the first direction 1 2.19um, the remaining 2 solid tubes 4 in the second direction have a thickness t 2 Is 1.56um. At a wavelength of 1550nm, the effective refractive index of the first polarization mode is 0.999384 in the direction and the effective refractive index of the second polarization mode perpendicular thereto is 0.999298, so that the birefringence is about 10 (-4) . Similarly, the solid ring size and distribution direction in the other surrounding cores are the same as those of the core, so that the birefringence direction is the same in the other surrounding cores, as shown in fig. 6; if the polarization directions of the surrounding fiber cores are required to be different, the distribution direction of the solid ring of each surrounding fiber core is adjusted according to the figure, as shown in fig. 7.
The foregoing is merely one specific embodiment of the present application and any other modifications made based on the concepts of the present application are contemplated as falling within the scope of the present application.
Claims (10)
1. A hollow fiber for a laser beam coupler, the hollow fiber comprising:
a first hollow core;
the second hollow fiber cores are arranged in a plurality, and the second hollow fiber cores are circumferentially distributed by taking the first hollow fiber core as a circle center; the second hollow fiber core is communicated with the first hollow fiber core through an air channel;
the photonic crystal cladding is arranged on the outer side of each second hollow fiber core in a surrounding mode, the photonic crystal cladding comprises an inner cladding arranged on the outer side of each second hollow fiber core in a surrounding mode, and the inner cladding comprises a plurality of solid tubes; and
the outer cladding layers are wrapped on the outer sides of the photonic crystal cladding layers;
the first hollow fiber cores and the second hollow fiber cores are the same in size, and the polarization directions of the second hollow fiber cores are the same or different.
2. The hollow-core optical fiber of claim 1, wherein the thickness of a plurality of said solid tubes is the same such that the polarization direction of a plurality of said second hollow cores is the same; or (b)
The thickness of a portion of the solid tube differs from the thickness of the remaining portion of the solid tube such that the polarization direction of the plurality of second hollow cores differs.
3. The hollow-core optical fiber of claim 2 wherein the distance from the center of the first hollow core to the center of either of the second hollow cores is 2-3 times the diameter of the first hollow core or the second hollow core.
4. The hollow-core optical fiber of claim 1 wherein the inner cladding and the outer cladding are the same material.
5. The hollow fiber of claim 4, wherein a plurality of said solid tubes are circumferentially distributed about said second hollow core;
the structures of the solid pipes are the same; the thickness of each of the solid tubes ranges from 0.2 to 2 μm.
6. The hollow-core optical fiber according to claim 4, wherein the inner cladding surrounding the air passage has a concave arc shape.
7. The hollow-core optical fiber of claim 4 wherein the refractive index of the gas within the air channel is less than the refractive index of the material of the inner cladding or the outer cladding.
8. The hollow-core optical fiber of claim 7 wherein the first hollow core has a first gas and the second hollow core has a second gas, the first gas having the same refractive index as the second gas.
9. The hollow-core optical fiber of claim 8, wherein the refractive index of the gas within the air channel is equal to the refractive indices of the first gas and the second gas.
10. A laser beam coupler comprising a hollow fiber as claimed in any one of claims 1 to 9.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311542454.7A CN117518340A (en) | 2023-11-20 | 2023-11-20 | Hollow optical fiber and laser beam coupler |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202311542454.7A CN117518340A (en) | 2023-11-20 | 2023-11-20 | Hollow optical fiber and laser beam coupler |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN117518340A true CN117518340A (en) | 2024-02-06 |
Family
ID=89762228
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202311542454.7A Pending CN117518340A (en) | 2023-11-20 | 2023-11-20 | Hollow optical fiber and laser beam coupler |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN117518340A (en) |
-
2023
- 2023-11-20 CN CN202311542454.7A patent/CN117518340A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100585438C (en) | A kind of high non-linear single polarization single-mould photonic crystal fiber | |
| US6301420B1 (en) | Multicore optical fibre | |
| Lou et al. | Ultra-short polarization beam splitter with square lattice and gold film based on dual-core photonic crystal fiber | |
| US8509581B2 (en) | Optical fibers with tubular optical cores | |
| JP5307558B2 (en) | Multi-core photonic bandgap fiber with inter-core coupling | |
| US9348086B2 (en) | Few-mode optical fibers | |
| CN111090148B (en) | Multi-core optical fiber multiplexing and demultiplexing device and method based on super-surface lens | |
| JP5876612B2 (en) | Fiber optic coupler for combining a signal beam with a non-circular light beam | |
| US20070201805A1 (en) | Optical transmission device and light-receiving module | |
| JP5311417B2 (en) | Optical fiber manufacturing method, optical fiber preform and manufacturing method thereof | |
| CN112230329A (en) | Single-polarization low-loss hollow negative-curvature optical fiber | |
| CN116840966A (en) | High-birefringence quasi-elliptical core hollow anti-resonance optical fiber applied to near infrared band (1.3-1.8 mu m) | |
| Yang et al. | A hollow-core circular photonic crystal fiber mode selective coupler for generating orbital angular momentum modes | |
| CN107643561A (en) | A kind of low-loss terahertz polarization beam splitter | |
| CN208207272U (en) | A kind of high birefringence double-core photonic crystal fiber polarization beam apparatus | |
| CN117518340A (en) | Hollow optical fiber and laser beam coupler | |
| CN113568089B (en) | Mode division multiplexer based on multicore annular photon lantern | |
| CN113900183B (en) | Terahertz polarization beam splitter based on double-core negative curvature optical fiber | |
| CN112099130B (en) | Slope-type refractive index distribution multi-core optical fiber with low crosstalk between cores | |
| CN213482499U (en) | Novel multi-mode orbital angular momentum long-distance transmission optical fiber | |
| CN115185034A (en) | Single-polarization hollow anti-resonance optical fiber | |
| WO2022029871A1 (en) | Optical fiber | |
| Goel et al. | Exploiting resonant band of antiresonant hollow core fiber for highly birefringent inline fiber polarizer | |
| Carvalho et al. | Plasmonic modal and polarization filter based on a fractal-like photonic crystal fiber | |
| CN112859245B (en) | Double-core terahertz optical fiber coupler |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |