A compact single-mode polarization beam splitter based on double hollow-core antiresonant fibers

Abstract

The present invention relates to the technical field of optical devices, and in particular to a compact single-mode polarization beam splitter based on a double hollow-core anti-resonant optical fiber, comprising: a rectangular dielectric layer that meets the thickness requirements is arranged in an outer sleeve and passes through the center line of the outer sleeve, the rectangular dielectric layer separates the fiber core to form two fiber cores; a plurality of dielectric tubes are symmetrically distributed in the outer sleeve with the rectangular dielectric layer as the center, each dielectric tube is tangent to the outer sleeve, and the two fiber cores are composed of the area surrounded by the dielectric tube and the rectangular dielectric layer. When a light wave is incident from any fiber core, the x-polarization fundamental mode and the y-polarization fundamental mode generated by the light wave are periodically transferred between the two fiber cores respectively, and the coupling length of the x-polarization fundamental mode and the coupling length of the y-polarization fundamental mode are obtained. Compared with the prior art, the present invention uses a rectangular dielectric layer to separate the double cores, which not only reduces the difficulty of preparing the device, but also significantly increases the coupling channel area between the double cores, thereby effectively reducing the coupling length.

Description

Technical Field

[0001] The invention relates to the technical field of optical devices, and in particular to a compact single-mode polarization beam splitter based on double hollow-core anti-resonance optical fibers. Background Art

[0002] With the continuous development of social informatization, the demand for network information transmission is increasing, and optical fiber communication technology is also gradually developing. Polarization beam splitters are essential components of optical communication systems. They can separate or merge incident light beams according to their polarization modes, and have become an indispensable component in the fields of optical communication systems, optical sensing technology, optical storage, and polarization imaging.

[0003] As the preferred material source for polarization beam splitters, double solid core fibers play a key role in the preparation of optical devices. However, due to the material properties, conventional polarization beam splitters based on double solid core fibers have large Fresnel reflections at the interface between silicon and air when connected to hollow core fibers, with a reflectivity usually exceeding 3.5%.

[0004] In recent years, double hollow core antiresonant fiber has gradually attracted people's attention as a new polarization beam splitter structure. The double hollow core antiresonant design gives the fiber polarization beam splitter higher flexibility and customizability, allowing designers to finely control the size, geometry and spacing of the hollow core according to specific application requirements. The increase in design freedom enables the polarization beam splitter to be optimized for different operating conditions and performance indicators, thereby achieving more effective polarization separation.

[0005] The polarization beam splitter disclosed in the prior art that can achieve an ultra-wideband polarization extinction ratio of less than -20dB mainly has the following problems:

[0006] (1) The coupling length of the polarization beam splitter is relatively long, reaching 8.15 cm, which is not very practical;

[0007] (ii) It is necessary to connect the dielectric tube tangentially on the outside of the dielectric tube, which increases the difficulty of device preparation. Summary of the invention

[0008] The present invention aims to at least improve one of the technical problems existing in the prior art. To this end, the present invention proposes a compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fibers.

[0009] According to the first aspect of the present invention, a compact single-mode polarization beam splitter based on a double hollow-core anti-resonant optical fiber comprises:

[0010] Outer sleeve;

[0011] A rectangular dielectric layer is disposed in the outer sleeve and passes through the center line of the outer sleeve, wherein the rectangular dielectric layer separates the fiber cores to form two fiber cores;

[0012] A plurality of medium tubes are symmetrically distributed in the outer sleeve with the rectangular medium layer as the center, and each of the medium tubes is tangent to the outer sleeve;

[0013] Wherein, the thickness of the rectangular dielectric layer Satisfy: 0.748μm< <0.807μm.

[0014] In a possible implementation of the first aspect, the dielectric tubes located on the same side of the rectangular dielectric layer in the outer sleeve include:

[0015] Class I medium pipes, the number of which is 2N, where N is a positive integer;

[0016] A type II medium pipe, wherein the type II medium pipe is arranged farther away from the rectangular medium layer than the type I medium pipe;

[0017] The compact single-mode polarization beam splitter further comprises:

[0018] The nested tube is located inside the class II dielectric tube and is tangent to the class II dielectric tube, so as to optimize the coupling length and reduce the loss of the polarization beam splitter at the same time.

[0019] In a possible implementation of the first aspect, the number of the Class II dielectric tubes located on the same side of the rectangular dielectric layer in the outer sleeve is M, where M is a positive integer and M≤2N;

[0020] The sum of the number of the medium tubes and the number of the nested tubes is not less than eight.

[0021] In a possible implementation of the first aspect, the thicknesses of the Class I dielectric tube, the Class II dielectric tube, and the nested tube are equal, so as to effectively adjust the operating wavelength of the compact single-mode polarization beam splitter based on the double hollow-core anti-resonant optical fiber so that it is in the transition zone from the anti-resonant wavelength to the resonant wavelength.

[0022] In a possible implementation manner of the first aspect, the outer sleeve includes two completely symmetrical semicircles or major arcs.

[0023] In a possible implementation manner of the first aspect, the outer sleeve is any one of a rectangular tube, a hexagonal tube, and an octagonal tube.

[0024] In a possible implementation manner of the first aspect, the outer sleeve, the medium tube, the nested tube, and the rectangular medium layer are made of the same material, and the structural material is silicon dioxide or plastic.

[0025] In a possible implementation of the first aspect, the two cores are both composed of a dielectric tube and an area surrounded by a rectangular dielectric layer, i.e., a first core and a second core. When a light wave is incident from the first core or the second core, the x-polarization fundamental mode and the y-polarization fundamental mode generated by the light wave are periodically transferred between the two cores, respectively, to obtain a coupling length of the x-polarization fundamental mode and a coupling length of the y-polarization fundamental mode, wherein the ratio of the coupling length of the x-polarization fundamental mode to the coupling length of the y-polarization fundamental mode is 2 or 0.5, at which time the device length is equal to the coupling length of the polarization fundamental mode with a longer coupling length, and the device length is twice the coupling length of the other polarization fundamental mode. Under this design, when the light beam is transmitted through the polarization beam splitter, the two polarization fundamental modes are output from the two cores respectively. This process effectively realizes the separation of polarization states, which facilitates subsequent optical processing or analysis.

[0026] According to the compact single-mode polarization beam splitter based on dual hollow-core antiresonant optical fibers according to the embodiments of the present invention, compared with the design of the polarization beam splitter disclosed in the prior art which requires a tangential connection to the dielectric tube on the outside of the dielectric tube, the present invention directly uses a rectangular dielectric layer to separate the dual cores, which not only reduces the difficulty of device preparation, but also significantly increases the coupling channel area between the dual cores, thereby effectively reducing the coupling length.

[0027] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 is a schematic cross-sectional structural diagram of a compact single-mode polarization beam splitter based on a double hollow-core anti-resonant optical fiber according to Embodiment 1 of the present invention;

[0030] Figure 2 is a graph showing a change in mode coupling length ratio versus wavelength of a compact single-mode polarization beam splitter based on a double hollow-core antiresonant optical fiber according to Example 1 of the present invention;

[0031] Figure 3 is a curve diagram showing a change in mode normalized power versus propagation length of a compact single-mode polarization beam splitter based on a double hollow-core antiresonant optical fiber according to Example 1 of the present invention;

[0032] Figure 4is a curve diagram showing the variation of polarization extinction ratio of a compact single-mode polarization beam splitter based on a double hollow-core antiresonant optical fiber according to Example 1 of the present invention with respect to wavelength;

[0033] Figure 5 is a graph showing changes in loss and high-order extinction ratio of a compact single-mode polarization beam splitter based on a double hollow-core antiresonant optical fiber as a function of wavelength according to Example 1 of the present invention;

[0034] Figure 6 is a schematic cross-sectional structural diagram of a compact single-mode polarization beam splitter based on a double hollow-core anti-resonant optical fiber according to Embodiment 2 of the present invention;

[0035] Figure 7 is a schematic cross-sectional structural diagram of a compact single-mode polarization beam splitter based on a double hollow-core anti-resonant optical fiber according to Embodiment 3 of the present invention;

[0036] Figure 8 It is a schematic diagram of the cross-sectional structure of a compact single-mode polarization beam splitter based on a double hollow-core antiresonant optical fiber according to Example 4 of the present invention.

[0037] Reference numerals:

[0038] Outer sleeve 1, rectangular dielectric layer 2;

[0039] Class I medium pipe 110, Class II medium pipe 120, nested pipe 130;

[0040] The first fiber core 310 and the second fiber core 320 . DETAILED DESCRIPTION

[0041] The embodiments of the present invention are described in detail below. The embodiments described with reference to the accompanying drawings are exemplary. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0042] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be an intermediate element at the same time.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0044] The terms "first", "second", "third", etc. in the specification and claims of the present application and the drawings are used to distinguish different objects rather than to describe a specific order. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a series of steps or units are included, or optionally, steps or units not listed are included, or optionally, other steps or units inherent to these processes, methods, products or devices are included.

[0045] Only the part relevant to the present application is shown in the accompanying drawings, but not all of the content. Before discussing the exemplary embodiments in more detail, it should be mentioned that some exemplary embodiments are described as processing or methods depicted as flow charts. Although the flow chart describes each operation (or step) as a sequential process, many of the operations therein can be implemented in parallel, concurrently or simultaneously. In addition, the order of each operation can be rearranged. When its operation is completed, the process can be terminated, but it can also have additional steps not included in the accompanying drawings. The process can correspond to a method, function, procedure, subroutine, subprogram, etc.

[0046] The terms "component", "module", "system", "unit", etc. used in this specification are used to represent computer-related entities, hardware, firmware, a combination of hardware and software, software, or software in execution. For example, a unit can be, but is not limited to, a process running on a processor, a processor, an object, an executable file, an execution thread, a program, and / or distributed between two or more computers. In addition, these units can be executed from various computer-readable media having various data structures stored thereon. Units can communicate through local and / or remote processes, for example, based on signals having one or more data packets (e.g., data from a second unit interacting with another unit in a local system, a distributed system, and / or a network. For example, the Internet interacts with other systems via signals).

[0047] Example 1

[0048] See also Figure 1 As shown, this embodiment provides a compact single-mode polarization beam splitter based on a double hollow-core anti-resonant optical fiber, which includes:

[0049] Outer sleeve 1;

[0050] A rectangular dielectric layer 2 is disposed in the outer sleeve 1 and passes through the center line of the outer sleeve 1. The rectangular dielectric layer 2 separates the fiber core to form two fiber cores.

[0051] A plurality of dielectric tubes are symmetrically distributed in the outer sleeve 1 with the rectangular dielectric layer 2 as the center, and each of the dielectric tubes is tangent to the outer sleeve;

[0052] Among them, the thickness of the rectangular dielectric layer 2 is Satisfy: 0.748μm< <0.807μm;

[0053] It should be noted that the dielectric pipes located on the same side of the rectangular dielectric layer in the outer sleeve 1 include:

[0054] Class I medium pipes 110, the number of which is 2N, where N is a positive integer;

[0055] A type II medium pipe 120, wherein the type II medium pipe 120 is arranged farther away from the rectangular medium layer 2 than the type I medium pipe 110;

[0056] The compact single-mode polarization beam splitter further comprises:

[0057] The nested tube 130 is located inside the type II dielectric tube 120 and is tangent to the type II dielectric tube 120 , so as to optimize the coupling length and reduce the loss of the polarization beam splitter.

[0058] It should be noted that the number of the type II dielectric tubes 120 located on the same side of the rectangular dielectric layer in the outer sleeve 1 is M, M is a positive integer, and M≤2N.

[0059] It should be noted that the thicknesses of the type I dielectric tube 110, the type II dielectric tube 120 and the nested tube 130 are equal, which facilitates the effective adjustment of the operating wavelength of the compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber so that it is in the transition zone from the anti-resonant wavelength to the resonant wavelength.

[0060] It should be noted that the two cores are both composed of the area surrounded by the dielectric tube and the rectangular dielectric layer 2, namely the first core 310 and the second core 320, wherein the first core 310 and the second core 320 are mode coupled through the rectangular dielectric layer 2, and since the thickness of the rectangular dielectric layer 2 is between the resonance and anti-resonance thicknesses, it partially transmits the working wavelength. The two cores are separated by the rectangular dielectric layer 2, and the operating mode can be coupled from one core to the other through the rectangular dielectric layer 2. At this time, the formation of the dual cores can be guaranteed, and the dual cores can be effectively coupled.

[0061] Furthermore, the light wave is incident from the first fiber core 310 or the second fiber core 320, and the x polarization fundamental mode and y polarization fundamental mode generated by the light wave are periodically transferred between the two fiber cores, respectively, to obtain the coupling length of the x polarization fundamental mode and the coupling length of the y polarization fundamental mode, and the polarization extinction ratio is obtained according to the ratio of the energy of the x polarization fundamental mode and the y polarization fundamental mode in the first fiber core 310 or the second fiber core 320; when the coupling length ratio of the respective coupling lengths meets the preset conditions and the polarization extinction ratio meets the requirements, the splitting of the X polarization light and the Y polarization light is realized. In this embodiment, the ratio of the coupling length of the x polarization fundamental mode to the coupling length of the y polarization fundamental mode is 2 or 0.5, at which time the device length is equal to the coupling length of the polarization fundamental mode with the longer coupling length, and the device length is twice the coupling length of the other polarization fundamental mode. Under this design, when the light beam is transmitted through the polarization beam splitter, the two polarization fundamental modes are output from the two fiber cores respectively. This process effectively realizes the separation of the polarization state, which provides convenience for subsequent optical processing or analysis.

[0062] It should be noted that according to the anti-resonance formula ,in, is the operating wavelength, t is the thickness of the rectangular dielectric layer 2, n is the material refractive index, m is a positive integer, and the resonant thickness of the polarization beam splitter at an operating wavelength of 1.55 μm is calculated to be approximately 0.748 μm. For light with a wavelength of 1.55 μm, the thickness is =0.748μm is transparent, so the polarization beam splitter cannot form an effective dual-core structure. =0.807μm, the fiber coupling length is as long as 10mm, which does not meet the short coupling length requirement. Therefore, the thickness of the rectangular dielectric layer 2 is The value range is greater than 0.748μm and less than 0.807μm. This is to meet the requirement that the operating wavelength of the compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber is in the transition zone from the anti-resonant wavelength to the resonant wavelength, has a partial transmission function, increases the coupling factor of the two fiber cores, and effectively shortens the coupling length.

[0063] It should be noted that the outer sleeve 1 includes two completely symmetrical semicircles or major arcs.

[0064] It should be noted that the outer sleeve 1 is any one of a rectangular tube, a hexagonal tube, and an octagonal tube.

[0065] It should be noted that the outer sleeve 1 , the dielectric tube, the nested tube 130 , and the rectangular dielectric layer 2 are made of the same material, which is silicon dioxide or plastic.

[0066] It should be noted that the total number of the Class II medium pipes 120 is any one of 2, 4, and 6.

[0067] It should be noted that the total number of the type I dielectric tubes 110 is 4 or 8, which is used to meet and reduce the loss of the polarization beam splitter.

[0068] According to the compact single-mode polarization beam splitter based on dual hollow-core antiresonant optical fibers according to the embodiments of the present invention, compared with the design of the polarization beam splitter disclosed in the prior art which requires a tangential connection to the dielectric tube on the outside of the dielectric tube, the present invention directly uses a rectangular dielectric layer to separate the dual cores, which not only reduces the difficulty of device preparation, but also significantly increases the coupling channel area between the dual cores, thereby effectively reducing the coupling length.

[0069] This embodiment provides the following specific implementation cases, which are as follows:

[0070] The outer sleeve 1, the dielectric tube, the nested tube 130 and the rectangular dielectric layer 2 are made of silicon dioxide.

[0071] The outer sleeve 1 is composed of two semicircles.

[0072] The thickness T of the type I medium tube 110 , the type II medium tube 120 , and the nested tube 130 are all 0.31 μm.

[0073] The diameter d1 of the type I medium tube 110 is 40.4 μm, and the number of the type I medium tubes 110 is four.

[0074] The diameter d2 of the type II medium tube 120 is 39.6 μm, and the number of the type II medium tubes 120 is two.

[0075] The diameter d3 of the nested tube 130 is 19.8 μm, and the number of the nested tubes 130 is two.

[0076] The thickness t of the rectangular dielectric layer 2 is 0.78 μm.

[0077] According to the optical fiber mode coupling theory, the x-polarization fundamental mode and the y-polarization fundamental mode each have two supermodes, namely, the x-polarization even supermode, the x-polarization odd supermode, the y-polarization even supermode, and the y-polarization odd supermode. When a beam of light is input from the first fiber core 310, the shortest distance required for mode coupling with the second fiber core 320 is called the coupling length: ,in is the coupling length between the x-polarization fundamental mode and the y-polarization fundamental mode, is the working wavelength, is the difference in effective refractive index between odd and even modes of the x-polarization fundamental mode and the y-polarization fundamental mode. The compact single-mode polarization beam splitter based on double hollow-core antiresonant optical fiber injects light waves from the first fiber core 310 or the second fiber core 320, and the x-polarization fundamental mode and the y-polarization fundamental mode generated by the light waves are periodically transferred between the two fiber cores, respectively, to obtain the coupling length of the x-polarization fundamental mode and the coupling length of the y-polarization fundamental mode.

[0078] In order to obtain the best compact single-mode polarization beam splitter based on double hollow core antiresonant fiber, the ratio of the coupling length of the x-polarization fundamental mode to the coupling length of the y-polarization fundamental mode should be 2 or 0.5. The coupling length ratio is introduced, which is defined as the ratio of the coupling length of the x-polarization fundamental mode to the coupling length of the y-polarization fundamental mode.

[0079] Assuming that a beam of light is input from the first fiber core 310, when the coupling length ratio is 2, the y-polarized fundamental mode is output from the second fiber core 320 after one coupling, and the x-polarized fundamental mode is output from the first fiber core 310 after two couplings.

[0080] When the coupling length ratio is 0.5, the x-polarized fundamental mode is output from the second fiber core 320 after one coupling, and the y-polarized fundamental mode is output from the first fiber core 310 after two couplings.

[0081] like Figure 2 As shown, Figure 2 A graph showing the mode coupling length ratio of a compact single-mode polarization beam splitter based on a double hollow core antiresonant fiber according to an embodiment of the present invention as a function of wavelength is given. The coupling length of the x-polarization fundamental mode and the coupling length of the y-polarization fundamental mode gradually decrease with increasing wavelength, and the coupling length ratio also increases with increasing wavelength and is maintained within a range of 0.485 to 0.526. The beam splitting of the x-polarization fundamental mode and the y-polarization fundamental mode can be achieved.

[0082] like Figure 3 As shown, Figure 3 : is a graph showing the variation of the normalized power of the mode of the compact single-mode polarization beam splitter based on double hollow core antiresonant optical fiber with the propagation length according to an embodiment of the present invention; when the light wave is incident on the first fiber core 310 at a wavelength of 1.55 μm, the normalized power of the x-polarization fundamental mode and the y-polarization fundamental mode propagating along the optical fiber is as follows: Figure 3 As shown in the figure, when the propagation distance reaches 5.96 mm, the normalized power of the y-polarization fundamental mode in the first fiber core 310 drops to zero, and the normalized power of the x-polarization fundamental mode first drops to 0 and then rises back to 1. At this time, the x-polarization fundamental mode in the light beam incident from the first fiber core 310 is coupled back to the first fiber core 310 twice, and the y-polarization fundamental mode is coupled once and only exists in the second fiber core 320, indicating that the x-polarization fundamental mode and the y-polarization fundamental mode are well separated in the first fiber core 310 and the second fiber core 320.

[0083] The polarization extinction ratio is the ratio of the normalized powers of the two polarization modes. When the polarization extinction ratio is higher than 20dB, the x-polarization fundamental mode and the y-polarization fundamental mode can be effectively separated into two fiber cores.

[0084] like Figure 4 As shown, Figure 4 The graph of the polarization extinction ratio of the compact single-mode polarization beam splitter based on double hollow core anti-resonant optical fiber versus wavelength in the embodiment of the present invention is shown; when the polarization extinction ratio is greater than 20 dB, the wavelength range at this time is the effective bandwidth of the compact single-mode polarization beam splitter based on double hollow core anti-resonant optical fiber. Figure 4 In the wavelength range of 1545.8nm to 1553.8nm, the polarization extinction ratio is greater than 20dB.

[0085] Single-mode performance is also an important factor in measuring polarization beam splitters. Single-mode performance is determined by the high-order extinction ratio. The high-order extinction ratio is defined as the ratio of the lowest loss of the high-order mode to the highest loss of the base film. When the high-order extinction ratio is greater than 100, the difference between the loss of the high-order mode and the base film is large enough to be well separated during transmission, filtering out the high-order mode, thereby effectively achieving single-mode performance.

[0086] like Figure 5 As shown, Figure 5 1 is a graph showing the variation of loss and high-order extinction ratio of a compact single-mode polarization beam splitter based on a double hollow-core antiresonant optical fiber with wavelength according to an embodiment of the present invention; in the graph, LP 01 The basement membrane is shown in two LP 01 The modal loss curves with the highest loss in the category are named LP 01-1 and LP 01-2 , L.P. 11 For the higher order modes, two LP 11 The modal loss curves with the lowest loss in the category are LP 11-1 and LP 11-2 According to the curve, LP 01 The mode loss is almost maintained below 1dB / m, and the LP 01 The maximum mode loss is 0.354dB / m. 11 Mode loss is maintained at a high level, LP at 1550nm 11 The minimum mode loss is 89.495dB / m. In the wavelength range of 1544.25nm to 1554.55nm, the high-order extinction ratio is greater than 100, the high-order extinction ratio is 252.767 at 1550nm, and the high-order extinction ratio reaches a maximum of 266.379 at 1552nm. The above shows that the compact single-mode polarization beam splitter based on double hollow-core anti-resonant fiber has good single-mode characteristics in the wavelength range of 1544.25nm to 1554.55nm.

[0087] The embodiment of the present invention provides a compact single-mode polarization beam splitter based on a dual hollow-core anti-resonant optical fiber. By adjusting the thickness of the rectangular dielectric layer 2 in the dual-core anti-resonant optical fiber, a compact single-mode polarization beam splitter with a short coupling length (coupling length ratio is about 0.5) is obtained. By adjusting the outer diameters of the Class I dielectric tube 110 and the Class II dielectric tube 120 and the thicknesses of the Class I dielectric tube 110, the Class II dielectric tube 120 and the nested tube 130, single-mode performance can be achieved in the wavelength range of 1544.25nm to 1554.55nm, and the polarization extinction ratio is greater than 20dB in the wavelength range of 1545.8nm to 1553.8nm. The compact single-mode polarization beam splitter based on a dual hollow-core anti-resonant optical fiber proposed in this embodiment has a very short coupling length and good single-mode performance, and the structure has good application prospects in optical fiber communication systems. According to actual test calculations, the length of the compact single-mode polarization beam splitter based on dual hollow-core antiresonant optical fiber in this embodiment is 5.96 mm. Compared with the prior art, the coupling length is shorter, the practicality is high, and there is no need to connect the dielectric tube tangentially on the outside of the dielectric tube, which reduces the difficulty of device preparation.

[0088] Example 2

[0089] The present invention provides a compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber on the basis of embodiment 1, such as Figure 6 As shown, Figure 6 A cross-sectional schematic diagram of a compact single-mode polarization beam splitter based on a double hollow-core anti-resonant optical fiber is given, which includes an outer sleeve 1, a dielectric tube and a rectangular dielectric layer 2; the rectangular dielectric layer 2 is arranged in the outer sleeve 1 and passes through the center line of the outer sleeve 1, the rectangular dielectric layer 2 divides the fiber core into two mutually isolated fiber cores, a plurality of dielectric tubes are symmetrically distributed in the outer sleeve 1 with the rectangular dielectric layer 2 as the center, each of the dielectric tubes is tangent to the outer sleeve 1, wherein the two fiber cores are composed of the area surrounded by the dielectric tube and the rectangular dielectric layer 2, i.e., the first fiber core 310 and the second fiber core 320, and the light wave is incident from the first fiber core 310 or the second fiber core 320, and the x-polarization fundamental mode and the y-polarization fundamental mode generated by the light wave are periodically transferred between the two fiber cores, respectively, to obtain the coupling length of the x-polarization fundamental mode and the coupling length of the y-polarization fundamental mode. When the thickness of the rectangular dielectric layer 2 is selected, the operating wavelength is in the transition zone from the anti-resonance wavelength to the resonant wavelength, and has the function of partial transmission, which increases the coupling factor of the two fiber cores and effectively shortens the coupling length.

[0090] It should be noted that the dielectric pipes located on the same side of the rectangular dielectric layer in the outer sleeve 1 include:

[0091] Class I medium pipes 110, the number of which is 2N, where N is a positive integer;

[0092] A type II medium pipe 120, wherein the type II medium pipe 120 is arranged farther away from the rectangular medium layer 2 than the type I medium pipe 110;

[0093] The compact single-mode polarization beam splitter further comprises:

[0094] The nested tube 130 is located inside the type II dielectric tube 120 and is tangent to the type II dielectric tube 120 , so as to optimize the coupling length and reduce the loss of the polarization beam splitter.

[0095] It should be noted that the outer sleeve 1 is composed of two semicircles; in this embodiment, the number of the Class I medium tubes 110 is 4; the number of the Class II medium tubes 120 is 4; and the number of the nested tubes 130 is 4.

[0096] According to actual test calculations, the length of the compact single-mode polarization beam splitter based on dual hollow-core antiresonant optical fiber in this embodiment is close to 5.96 mm. Compared with the prior art, the coupling length is shorter, the practicality is high, and there is no need to connect the dielectric tube tangentially on the outside of the dielectric tube, which reduces the difficulty of device preparation.

[0097] Example 3

[0098] The present invention provides a compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber on the basis of embodiment 1, such as Figure 7 As shown, Figure 7 A cross-sectional schematic diagram of a compact single-mode polarization beam splitter based on a double hollow-core anti-resonant optical fiber is given, which includes an outer sleeve 1, a dielectric tube and a rectangular dielectric layer 2; the rectangular dielectric layer 2 is arranged in the outer sleeve 1 and passes through the center line of the outer sleeve 1, the rectangular dielectric layer 2 divides the fiber core into two mutually isolated fiber cores, a plurality of dielectric tubes are symmetrically distributed in the outer sleeve 1 with the rectangular dielectric layer 2 as the center, each of the dielectric tubes is tangent to the outer sleeve 1, wherein the two fiber cores are composed of the area surrounded by the dielectric tube and the rectangular dielectric layer 2, i.e., the first fiber core 310 and the second fiber core 320, and the light wave is incident from the first fiber core 310 or the second fiber core 320, and the x-polarization fundamental mode and the y-polarization fundamental mode generated by the light wave are periodically transferred between the two fiber cores, respectively, to obtain the coupling length of the x-polarization fundamental mode and the coupling length of the y-polarization fundamental mode. When the thickness of the rectangular dielectric layer 2 is selected, the operating wavelength is in the transition zone from the anti-resonance wavelength to the resonant wavelength, and has the function of partial transmission, which increases the coupling factor of the two fiber cores and effectively shortens the coupling length.

[0099] It should be noted that the dielectric pipes located on the same side of the rectangular dielectric layer in the outer sleeve 1 include:

[0100] Class I medium pipes 110, the number of which is 2N, where N is a positive integer;

[0101] A type II medium pipe 120, wherein the type II medium pipe 120 is arranged farther away from the rectangular medium layer 2 than the type I medium pipe 110;

[0102] The compact single-mode polarization beam splitter further comprises:

[0103] The nested tube 130 is located inside the type II dielectric tube 120 and is tangent to the type II dielectric tube 120 , so as to optimize the coupling length and reduce the loss of the polarization beam splitter.

[0104] It should be noted that the outer sleeve 1 is composed of two semicircles; in this embodiment, the number of Class I medium tubes 110 is 8; the number of Class II medium tubes 120 is 2; and the number of nested tubes 130 is 2.

[0105] According to actual test calculations, the length of the compact single-mode polarization beam splitter based on dual hollow-core antiresonant optical fiber in this embodiment is close to 5.96 mm. Compared with the prior art, the coupling length is shorter, the practicality is high, and there is no need to connect the dielectric tube tangentially on the outside of the dielectric tube, which reduces the difficulty of device preparation.

[0106] Example 4

[0107] The present invention provides a compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber on the basis of embodiment 1, such as Figure 8 As shown, Figure 8 A cross-sectional schematic diagram of a compact single-mode polarization beam splitter based on a double hollow-core anti-resonant optical fiber is given, which includes an outer sleeve 1, a dielectric tube and a rectangular dielectric layer 2; the rectangular dielectric layer 2 is arranged in the outer sleeve 1 and passes through the center line of the outer sleeve 1, the rectangular dielectric layer 2 divides the fiber core into two mutually isolated fiber cores, a plurality of dielectric tubes are symmetrically distributed in the outer sleeve 1 with the rectangular dielectric layer 2 as the center, each of the dielectric tubes is tangent to the outer sleeve 1, wherein the two fiber cores are composed of the area surrounded by the dielectric tube and the rectangular dielectric layer 2, i.e., the first fiber core 310 and the second fiber core 320, and the light wave is incident from the first fiber core 310 or the second fiber core 320, and the x-polarization fundamental mode and the y-polarization fundamental mode generated by the light wave are periodically transferred between the two fiber cores, respectively, to obtain the coupling length of the x-polarization fundamental mode and the coupling length of the y-polarization fundamental mode. When the thickness of the rectangular dielectric layer 2 is selected, the operating wavelength is in the transition zone from the anti-resonance wavelength to the resonant wavelength, and has the function of partial transmission, which increases the coupling factor of the two fiber cores and effectively shortens the coupling length.

[0108] It should be noted that the dielectric pipes located on the same side of the rectangular dielectric layer in the outer sleeve 1 include:

[0109] Class I medium pipes 110, the number of which is 2N, where N is a positive integer;

[0110] A type II medium pipe 120, wherein the type II medium pipe 120 is arranged farther away from the rectangular medium layer 2 than the type I medium pipe 110;

[0111] The compact single-mode polarization beam splitter further comprises:

[0112] The nested tube 130 is located inside the type II dielectric tube 120 and is tangent to the type II dielectric tube 120 , so as to optimize the coupling length and reduce the loss of the polarization beam splitter.

[0113] It should be noted that the outer sleeve 1 is composed of two major arcs; in this embodiment, the number of Class I medium pipes 110 is 4; the number of Class II medium pipes 120 is 2; and the number of nested pipes 130 is 2.

[0114] According to actual test calculations, the length of the compact single-mode polarization beam splitter based on dual hollow-core antiresonant optical fiber in this embodiment is close to 5.96 mm. Compared with the prior art, the coupling length is shorter, the practicality is high, and there is no need to connect the dielectric tube tangentially on the outside of the dielectric tube, which reduces the difficulty of device preparation.

[0115] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation to the invention.

[0116] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0117] Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Mentioning "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present embodiment application. The appearance of this phrase in various positions in the specification is not necessarily the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It can be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0118] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A compact single-mode polarization beam splitter based on double hollow-core antiresonant optical fiber, characterized in that: include: Outer sleeve (1); A rectangular dielectric layer (2) is arranged inside the outer sleeve (1) and passes through the center line of the outer sleeve (1), wherein the rectangular dielectric layer (2) separates the fiber cores to form two fiber cores; A plurality of dielectric tubes are symmetrically distributed in the outer sleeve (1) with the rectangular dielectric layer (2) as the center, each of the dielectric tubes being tangent to the outer sleeve (1), wherein the dielectric tubes in the outer sleeve (1) located on the same side of the rectangular dielectric layer include: Class I medium tubes (110), the number of the Class I medium tubes (110) being 2N, where N is a positive integer; A type II medium tube (120), wherein the type II medium tube (120) is arranged farther away from the rectangular medium layer (2) than the type I medium tube (110); A nested tube (130) located inside the Class II medium tube (120) and tangent to the Class II medium tube (120); The thickness of the rectangular dielectric layer (2) satisfies: 0.748 μm < <0.807μm.

2. The compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber according to claim 1, characterized in that: The number of the type II medium tubes (120) located on the same side of the rectangular medium layer in the outer sleeve (1) is M, where M is a positive integer and M≤2N.

3. The compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber according to claim 1, characterized in that: The sum of the number of the medium tubes and the number of the nested tubes (130) is not less than eight.

4. The compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber according to claim 1, characterized in that: The thicknesses of the Class I medium tube (110), the Class II medium tube (120), and the nested tube (130) are equal.

5. The compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber according to claim 1, characterized in that: The two fiber cores are both composed of an area surrounded by a dielectric tube and a rectangular dielectric layer (2), namely a first fiber core (310) and a second fiber core (320). When a light wave is incident from the first fiber core (310) or the second fiber core (320), an x-polarization fundamental mode and a y-polarization fundamental mode generated by the light wave are periodically transferred between the two fiber cores respectively, thereby obtaining a coupling length of the x-polarization fundamental mode and a coupling length of the y-polarization fundamental mode, wherein the ratio of the coupling length of the x-polarization fundamental mode to the coupling length of the y-polarization fundamental mode is 2 or 0.

5.

6. The compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber according to claim 1, characterized in that: The outer sleeve (1) comprises two completely symmetrical semicircles or major arcs.

7. The compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber according to claim 1, characterized in that: The outer sleeve (1) is any one of a rectangular tube, a hexagonal tube, and an octagonal tube.

8. The compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber according to claim 1, characterized in that: The outer sleeve (1), the medium tube, the nested tube (130) and the rectangular medium layer (2) are made of the same material.

9. The compact single-mode polarization beam splitter based on double hollow-core anti-resonant optical fiber according to claim 8, characterized in that: The material is silicon dioxide or plastic.

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