WO2023138370A1 - 抗弯曲低串扰光子轨道角动量光纤波导 - Google Patents

抗弯曲低串扰光子轨道角动量光纤波导 Download PDF

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WO2023138370A1
WO2023138370A1 PCT/CN2023/070373 CN2023070373W WO2023138370A1 WO 2023138370 A1 WO2023138370 A1 WO 2023138370A1 CN 2023070373 W CN2023070373 W CN 2023070373W WO 2023138370 A1 WO2023138370 A1 WO 2023138370A1
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refractive index
oam
cladding
crosstalk
angular momentum
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PCT/CN2023/070373
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English (en)
French (fr)
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陈伟
庞拂飞
王廷云
黄素娟
张小贝
文建湘
董艳华
黄怿
张颖
王洋
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上海大学
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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
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02042—Multicore optical fibres
    • 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
    • G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
    • G02B6/0281—Graded index region forming part of the central core segment, e.g. alpha profile, triangular, trapezoidal core
    • 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
    • G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
    • G02B6/0283—Graded index region external to the central core segment, e.g. sloping layer or triangular or trapezoidal layer
    • G02B6/0285—Graded index layer adjacent to the central core segment and ending at the outer cladding index
    • 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
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03605—Highest refractive index not on central axis
    • G02B6/03611—Highest index adjacent to central axis region, e.g. annular core, coaxial ring, centreline depression affecting waveguiding
    • 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
    • G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
    • G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
    • G02B6/03661—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 4 layers only
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A30/00—Adapting or protecting infrastructure or their operation

Definitions

  • the invention relates to a novel optical waveguide for space division multiplexing in the field of optical fiber communication, in particular to a bending-resistant low-crosstalk photon orbital angular momentum (OAM) optical fiber.
  • OAM photon orbital angular momentum
  • orbital angular momentum represents the rotation of electrons around the propagation axis, which is generated by the rotation of the energy flow (described by the Poynting vector) around the optical axis, which makes the phase front of the electromagnetic wave vortex.
  • SAM Spin Angular Momentum (Spin Angular Momentum), the spin angular momentum is only related to the spin of the photon, which is expressed as a circular polarization state.
  • Refractive Index Profile The relationship between the refractive index of an optical fiber or optical fiber preform (including the core rod) and its radius.
  • QAM Quadrature Amplitude Modulation (Quadrature Amplitude Modulation)
  • MIMO Multiple-Input Multiple-Output
  • Shannon limit The Shannon limit or Shannon capacity of a communication channel is the theoretical maximum information transfer rate of the channel for a specified noise level.
  • Quantum tunneling effect is a quantum property in which microscopic particles such as electrons can penetrate or pass through the quantum behavior of the potential barrier, although the height of the potential barrier is greater than the total energy of the particle. According to quantum mechanics, microscopic particles have the properties of waves, and have a non-zero probability of passing through the potential barrier.
  • OAM photon orbital angular momentum fiber can carry photon orbital angular momentum information. From the perspective of scientific theory, it can be inferred that the number of topological charges of orbital angular momentum can be infinitely expanded, which can effectively expand the scale of optical communication multiplexing. Photons not only have linear momentum along the longitudinal direction of propagation, but also have angular momentum related to the polarization characteristics of light, that is, spin angular momentum (SAM).
  • SAM spin angular momentum
  • OAM is different from SAM.
  • the OAM beam has a phase structure related to the angular phase distribution, so it carries orbital angular momentum.
  • Photon orbital angular momentum OAM corresponds to infinitely many eigenvalues.
  • Hilbert infinite-dimensional space can be constructed. It has infinitely many eigenmodes, and each mode is orthogonal to each other. Realize high-capacity, high-speed, large-scale optical communication network networking.
  • OAM beams are mainly divided into generation in space and generation in optical fibers. There are two ways to generate OAM mode beams in space: the first method uses lasers to directly output OAM beams, which is generated in the cavity.
  • the laser beam is modulated in the laser cavity to generate OAM beams, but the generation cost of such OAM beams is high, the stability of OAM modes is easily affected, and the purity of OAM modes is low;
  • the second method is to use spatial structure devices, but there are many devices and complex structures, which also face the problems of OAM mode stability and mode purity;
  • the third method is to generate and transmit in optical fibers. structure, and the phase purity is higher, and the OAM beam is obtained by the superposition of the corresponding order vector mode in the corresponding fiber, and the phase purity is higher.
  • US patent US20190170933A1 proposes a vortex optical fiber for optical imaging for multi-mode illumination.
  • This optical fiber can generate two-order OAM modes and is mainly used to generate circular beams for illumination.
  • the transmission distance is short and it is not suitable for applications in the communication field.
  • the world patent WO2017210679A1 proposes a system and method for manufacturing a vortex fiber, but this method does not explicitly mention the structural parameters and OAM mode characteristics of the vortex fiber.
  • U.S. Patent US8948559B2 proposes a space-division multiplexing multi-linear polarization mode fiber.
  • the fiber core has a graded parabolic refractive index distribution. By reducing the relative refractive index difference of the fiber core to 0.8%, 2 to 4 few modes are obtained, and Rayleigh scattering loss can be reduced.
  • the patent does not specify the characteristics and performance parameters of its OAM mode.
  • U.S. Patent US8705922B2 proposes a four-mode optical fiber.
  • the fiber core has a high refractive index.
  • the core refractive index profile is a parabolic distribution.
  • the parameter g of the parabolic profile ranges from 1.9 to 2.1.
  • the DGD time delay at a wavelength of 1550 nm is 150 ps/km.
  • the patent does not specify the characteristics and performance parameters of the OAM mode.
  • Chinese patent CN110297288A proposes a low-attenuation step-type orbital angular momentum fiber.
  • the waveguide structure is complex, and the distribution of the refractive index needs to be well controlled.
  • the manufacturing method is harsh, the realization is difficult, and the mode crosstalk needs to be further improved.
  • Chinese patent CN110333572A proposes a low-attenuation graded orbital angular momentum fiber.
  • the fiber waveguide structure is basically similar to CN110297288A, and the refractive index is graded in the depression of the annular part. This structure is difficult to implement, and the mode crosstalk needs to be further improved.
  • Chinese patent CN108680990A proposes a ring-core orbital angular momentum fiber, but its attenuation is greater than 1dB/km, which is suitable for short-distance transmission;
  • Chinese patent CN106338793A proposes a ring-core fiber that can suppress some high-order modes that are easy to couple, but its attenuation reaches 0.31dB/km, which still has a certain distance from the low-loss attenuation index.
  • Chinese patent CN105242347A proposes a high-purity, low intrinsic crosstalk orbital angular momentum transmission fiber.
  • the fiber core refractive index profile adopts a parabolic distribution, the refractive index distribution parameter g value is greater than 2.1, and the refractive difference between the core and the cladding reaches 0.10. It is difficult to realize in the communication optical fiber quartz system, the mode crosstalk is difficult to control, and the attenuation is difficult to reduce to meet the requirements of long-distance transmission.
  • the technical problem to be solved by the present invention is:
  • the traditional optical fiber and the reported invention patents cannot well solve the demand for the development of photon orbital angular momentum (OAM) channel transmission in the field of large-capacity space-division multiplexing optical fiber communication systems.
  • the present invention proposes a bending-resistant low-crosstalk photon orbital angular momentum optical waveguide to solve the major practical needs of space-division multiplexing technology for next-generation optical fiber communication systems.
  • the optical fiber waveguide can regulate four different orders of photon orbital angular momentum OAM modes in the wavelength range of 1530nm to 1565nm. It has strong bending resistance, easy separation of modes and low crosstalk between modes.
  • the waveguide structure is suitable for large-scale production and can be applied to stable transmission of long-distance optical fiber communication systems.
  • a bending-resistant low-crosstalk photon orbital angular momentum fiber waveguide The fiber is sequentially composed of the first core layer, the second core layer, the first cladding layer, the second cladding layer, and the third cladding layer from the center to the outside.
  • the third cladding layer is the thickest, the first core layer, and the first cladding layer is the thinnest; the first cladding layer has the smallest refractive index, and the second cladding layer has the largest refractive index.
  • the difference between the refractive index n 1 of the first core layer and the refractive index n 5 of the third cladding layer is -0.00029 to -0.01603.
  • the refractive index difference between the second core refractive index n 2 and the third cladding refractive index n 5 is 0.017485 to 0.037885.
  • the refractive index difference between the refractive index n3 and the third cladding layer refractive index n5 is -0.005 to -0.0153.
  • the refractive index difference between the second cladding refraction n4 and the third cladding refraction n5 is -0.005 to -0.0153.
  • the refractive index curve of the second core layer refractive index n2 gradually changes and satisfies the refractive index profile distribution function:
  • g is -2, -3, 2, 3 or 5.
  • the optical fiber can control the output of four different orders of OAM modes to achieve stable transmission, OAM-0 order, OAM- ⁇ 1 order, OAM- ⁇ 2 order and OAM- ⁇ 3 order, and the effective refractive index difference between each OAM mode is greater than 1.52 ⁇ 10 -4 .
  • the bending loss of each OAM mode of the fiber at the wavelength of 1550nm is small, and the macrobending loss of R5mm bending for 1 turn is less than or equal to 0.50dB; the crosstalk between the optical fiber OAM-0 order and OAM- ⁇ 1 order mode is less than -9dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -16dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -15dB/80km, The crosstalk between OAM- ⁇ 1st order and OAM- ⁇ 3rd order modes is less than -25dB/80km.
  • the waveguide structure of the present invention can effectively control the output of different modes of OAM orbital angular momentum, the effective refractive index difference between the modes is greater than 2 ⁇ 10 -4 , the modes are easy to separate, and it is convenient for multiplexing and demultiplexing.
  • the waveguide of the present invention has good bending resistance, the bending loss of each OAM mode at a wavelength of 1550nm is small, the macrobending loss of one R5mm bending is less than or equal to 0.50dB, and the bending additional loss is small, which can adapt to complex application environments such as bending, and improve the reliability of applications.
  • the waveguide OAM orbital angular momentum of the present invention has high purity and low crosstalk between modes, is suitable for long-distance transmission of optical fiber communication SDM space division multiplexing system, can meet the requirements of 400G high-speed transmission system, and has good application prospects and economic and social benefits.
  • the waveguide structure of the present invention is stable, easy to implement, can improve production efficiency, and is suitable for large-scale production.
  • Fig. 1 is the schematic diagram of the refractive index profile structure of the fiber waveguide of the present invention
  • Fig. 2 is a schematic diagram of the end face structure of the optical fiber waveguide of the present invention.
  • 1-first core layer 2-second core layer, 3-first cladding layer, 4-second cladding layer, 5-third cladding layer, 6-inner coating layer, 7-outer coating layer
  • the present invention provides a photon orbital angular momentum (OAM) optical fiber waveguide, which is composed of two core layers, three cladding layers and coating layers, characterized in that: from the center to the outside, it is composed of the first core layer (r 1 ), the second core layer (r 2 ), the first cladding layer (r 3 ), the second cladding layer (r 4 ), the third cladding layer (r 5 ), and the coating layer outside the third cladding layer. It consists of an inner coating (6 in Figure 2) and an outer coating (7 in Figure 2).
  • OAM photon orbital angular momentum
  • the third cladding layer is the thickest, the first cladding layer is the thinnest, and the first cladding layer is the thinnest; the first cladding layer has the smallest refractive index, and the second cladding layer has the largest refractive index.
  • the difference between the refractive index n 1 of the first core layer and the refractive index n 5 of the third cladding layer is -0.00029 to -0.01603.
  • the refractive index difference between the second core refractive index n 2 and the third cladding refractive index n 5 is 0.017485.
  • the refractive index difference between the first cladding refractive index n 3 and the third cladding refractive index n 5 is -0.005 to -0.0153, the cladding waveguide structure has a quantum tunneling effect, which can control the loss characteristics of the mode;
  • the refractive index difference between the second cladding refractive index n 4 and the third cladding refractive index n 5 is -0.005 to -0.0153.
  • the photonic orbital angular momentum fiber waveguide can control the output of four different order OAM modes in the wavelength range of 1530nm to 1565nm to achieve stable transmission, OAM-0 order, OAM- ⁇ 1 order, OAM- ⁇ 2 order and OAM- ⁇ 3 order, and the effective refractive index difference between each OAM mode is greater than 1.52 ⁇ 10 -4 .
  • the bending loss of each OAM mode of the photon orbital angular momentum fiber waveguide at a wavelength of 1550nm is small, and the macrobending loss of one R5mm bending is less than or equal to 0.50dB.
  • the crosstalk between the OAM-0 order and OAM- ⁇ 1 order modes of the photonic orbital angular momentum fiber waveguide is less than -9dB/80km;
  • the present invention provides a photon orbital angular momentum (OAM) optical fiber waveguide.
  • the optical fiber waveguide is composed of two core layers, three cladding layers and a coating layer. It is characterized in that: the first core layer (r 1 ), the second core layer (r 2 ), the first cladding layer (r 3 ), the second cladding layer (r 4 ), and the third cladding layer (r 5 ) are formed from the center to the outside, and an inner coating layer and an outer coating layer outside the third cladding layer. Light curing.
  • the refractive index difference between the first core refractive index n 1 and the third cladding refractive index n 5 is -0.00029.
  • the refractive index difference between the second core refractive index n 2 and the third cladding refractive index n 5 is 0.017485.
  • the refractive index difference between the first cladding refractive index n3 and the third cladding refractive index n5 is -0.005, and the cladding waveguide structure has a quantum tunneling effect, which can control the loss characteristics of the mode;
  • the refractive index difference between the second cladding refractive index n4 and the third cladding refractive index n5 is -0.00.
  • the photonic orbital angular momentum fiber waveguide can control the output of four different order OAM modes in the wavelength range of 1530nm to 1565nm to achieve stable transmission, OAM-0 order, OAM- ⁇ 1 order, OAM- ⁇ 2 order and OAM- ⁇ 3 order, and the effective refractive index difference between each OAM mode is greater than 1.53 ⁇ 10 -4 (see Table 1).
  • the bending loss of each OAM mode of the photon orbital angular momentum fiber waveguide at a wavelength of 1550nm is small, and the macrobending loss of R5mm bending for one turn is less than or equal to 0.50dB (see Table 1).
  • the crosstalk between the photonic orbital angular momentum fiber waveguide OAM-0 order and OAM- ⁇ 1 order mode is less than -9dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -16dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -15dB/80km, and the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 3 order mode is less than -25dB/80km (see table 1).
  • the invention provides a photon orbital angular momentum (OAM) optical fiber waveguide, which is composed of two core layers, three cladding layers and a coating layer, and is characterized in that: from the center to the outside, it consists of a first core layer (r 1 ), a second core layer (r 2 ), a first cladding layer (r 3 ), a second cladding layer (r 4 ), a third cladding layer (r 5 ), and a coating layer outside the third cladding layer.
  • OAM photon orbital angular momentum
  • the refractive index difference between the first core refractive index n 1 and the third cladding refractive index n 5 is -0.01603.
  • the refractive index difference between the second core refractive index n 2 and the third cladding refractive index n 5 is 0.037885.
  • the refractive index difference between the first cladding refractive index n 3 and the third cladding refractive index n 5 is -0.0153.
  • the cladding waveguide structure has a quantum tunneling effect, which can control the loss characteristics of the mode; the refractive index difference between the second cladding refractive index n 4 and the third cladding refractive index n 5 is -0.0153.
  • the photonic orbital angular momentum fiber waveguide can control the output of four different orders of OAM modes in the wavelength range of 1530nm to 1565nm to achieve stable transmission, OAM-0 order, OAM- ⁇ 1 order, OAM- ⁇ 2 order and OAM- ⁇ 3 order, and the effective refractive index difference between each OAM mode is greater than 1.52 ⁇ 10 -4 (see Table 1).
  • the bending loss of each OAM mode of the photon orbital angular momentum fiber waveguide at a wavelength of 1550nm is small, and the macrobending loss of one R5mm bending is less than or equal to 0.37dB (see Table 1).
  • the crosstalk between the photonic orbital angular momentum fiber waveguide OAM-0 order and OAM- ⁇ 1 order mode is less than -9dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -16dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -15dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 3 order mode is less than -25dB/80km (see table 1).
  • the invention provides a photon orbital angular momentum (OAM) optical fiber waveguide, which is composed of two core layers, three cladding layers and a coating layer, and is characterized in that: from the center to the outside, it consists of a first core layer (r 1 ), a second core layer (r 2 ), a first cladding layer (r 3 ), a second cladding layer (r 4 ), a third cladding layer (r 5 ), and a coating layer outside the third cladding layer.
  • OAM photon orbital angular momentum
  • the refractive index difference between the first core refractive index n 1 and the third cladding refractive index n 5 is -0.00949.
  • the difference between the refractive index n 2 of the second core layer and the refractive index n 5 of the third cladding layer is 0.029146.
  • the refractive index difference between the first cladding refractive index n 3 and the third cladding refractive index n 5 is -0.01093.
  • the cladding waveguide structure has a quantum tunneling effect, which can control the loss characteristics of the mode; the refractive index difference between the second cladding refractive index n 4 and the third cladding refractive index n 5 is -0.00729.
  • the photonic orbital angular momentum fiber waveguide can control the output of four different order OAM modes in the wavelength range of 1530nm to 1565nm to achieve stable transmission, OAM-0 order, OAM- ⁇ 1 order, OAM- ⁇ 2 order and OAM- ⁇ 3 order, and the effective refractive index difference between each OAM mode is greater than 1.52 ⁇ 10 -4 (see Table 1).
  • the bending loss of each OAM mode of the photonic orbital angular momentum fiber waveguide at a wavelength of 1550nm is small, and the macrobending loss of one R5mm bending is less than or equal to 0.43dB (see Table 1).
  • the crosstalk between the photonic orbital angular momentum fiber waveguide OAM-0 order and OAM- ⁇ 1 order mode is less than -9dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -16dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -15dB/80km, and the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 3 order mode is less than -25dB/80km (see table 1).
  • the invention provides a photon orbital angular momentum (OAM) optical fiber waveguide, which is composed of two core layers, three cladding layers and a coating layer, and is characterized in that: from the center to the outside, it consists of a first core layer (r 1 ), a second core layer (r 2 ), a first cladding layer (r 3 ), a second cladding layer (r 4 ), a third cladding layer (r 5 ), and a coating layer outside the third cladding layer.
  • OAM photon orbital angular momentum
  • the refractive index difference between the first core refractive index n 1 and the third cladding refractive index n 5 is -0.01392.
  • the refractive index difference between the second core refractive index n 2 and the third cladding refractive index n 5 is 0.032056.
  • the refractive index difference between the first cladding refractive index n 3 and the third cladding refractive index n 5 is -0.011953.
  • the cladding waveguide structure has a quantum tunneling effect, which can control the loss characteristics of the mode; the refractive index difference between the second cladding refractive index n 4 and the third cladding refractive index n 5 is -0.009651.
  • the photonic orbital angular momentum fiber waveguide can control the output of four different order OAM modes in the wavelength range of 1530nm to 1565nm to achieve stable transmission, OAM-0 order, OAM- ⁇ 1 order, OAM- ⁇ 2 order and OAM- ⁇ 3 order, and the effective refractive index difference between each OAM mode is greater than 1.52 ⁇ 10 -4 (see Table 1).
  • the bending loss of each OAM mode of the photonic orbital angular momentum fiber waveguide at a wavelength of 1550nm is small, and the macrobending loss of one R5mm bending is less than or equal to 0.45dB (see Table 1).
  • the crosstalk between the photonic orbital angular momentum fiber waveguide OAM-0 order and OAM- ⁇ 1 order mode is less than -9dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -16dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -15dB/80km, and the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 3 order mode is less than -25dB/80km (see table 1).
  • the invention provides a photon orbital angular momentum (OAM) optical fiber waveguide, which is composed of two core layers, three cladding layers and a coating layer, and is characterized in that: from the center to the outside, it consists of a first core layer (r 1 ), a second core layer (r 2 ), a first cladding layer (r 3 ), a second cladding layer (r 4 ), a third cladding layer (r 5 ), and a coating layer outside the third cladding layer.
  • OAM photon orbital angular momentum
  • the refractive index difference between the first core refractive index n 1 and the third cladding refractive index n 5 is -0.01506.
  • the refractive index difference between the second core refractive index n 2 and the third cladding refractive index n 5 is 0.027399.
  • the refractive index difference between the first cladding refractive index n 3 and the third cladding refractive index n 5 is 0; the refractive index difference between the second cladding refractive index n 4 and the third cladding refractive index n 5 is -0.00939.
  • the photonic orbital angular momentum fiber waveguide can control the output of four different order OAM modes in the wavelength range of 1530nm to 1565nm to achieve stable transmission, OAM-0 order, OAM- ⁇ 1 order, OAM- ⁇ 2 order and OAM- ⁇ 3 order, and the effective refractive index difference between each OAM mode is greater than 1.52 ⁇ 10 -4 (see Table 1).
  • the bending loss of each OAM mode of the photonic orbital angular momentum fiber waveguide at a wavelength of 1550nm is small, and the macrobending loss of one R5mm bending is less than or equal to 0.45dB (see Table 1).
  • the crosstalk between the photonic orbital angular momentum fiber waveguide OAM-0 order and OAM- ⁇ 1 order mode is less than -9dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -16dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -15dB/80km, and the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 3 order mode is less than -25dB/80km (see table 1).
  • the invention provides a photon orbital angular momentum (OAM) optical fiber waveguide, which is composed of two core layers, three cladding layers and a coating layer, and is characterized in that: from the center to the outside, it consists of a first core layer (r 1 ), a second core layer (r 2 ), a first cladding layer (r 3 ), a second cladding layer (r 4 ), a third cladding layer (r 5 ), and a coating layer outside the third cladding layer.
  • OAM photon orbital angular momentum
  • the refractive index difference between the first core refractive index n 1 and the third cladding refractive index n 5 is -0.01039.
  • the refractive index difference between the second core refractive index n 2 and the third cladding refractive index n 5 is 0.035065.
  • the refractive index difference between the first cladding refractive index n 3 and the third cladding refractive index n 5 is -0.00796.
  • the cladding waveguide structure has a quantum tunneling effect, which can control the loss characteristics of the mode; the refractive index difference between the second cladding refractive index n 4 and the third cladding refractive index n 5 is -0.00856.
  • the photonic orbital angular momentum fiber waveguide can control the output of four different order OAM modes in the wavelength range of 1530nm to 1565nm to achieve stable transmission, OAM-0 order, OAM- ⁇ 1 order, OAM- ⁇ 2 order and OAM- ⁇ 3 order, and the effective refractive index difference between each OAM mode is greater than 1.52 ⁇ 10 -4 (see Table 1).
  • the bending loss of each OAM mode of the photon orbital angular momentum fiber waveguide at a wavelength of 1550nm is small, and the macrobending loss of one R5mm bending is less than or equal to 0.46dB (see Table 1).
  • the crosstalk between the photonic orbital angular momentum fiber waveguide OAM-0 order and OAM- ⁇ 1 order mode is less than -9dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -16dB/80km, the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 2 order mode is less than -15dB/80km, and the crosstalk between OAM- ⁇ 1 order and OAM- ⁇ 3 order mode is less than -25dB/80km (see table 1).
  • the main performance indicators of the fiber waveguide in the above implementation examples are shown in Table 1.

Abstract

一种抗弯曲低串扰光子轨道角动量光纤波导，光纤从中心向外依次为第一芯层（1）、第二芯层（2）、第一包层（3）、第二包层（4）、和第三包层（5），其中第三包层（5）最厚，第一芯层（1）次之，第一包层（3）最薄；第一包层（3）的折射率最小，第二包层（4）次之，第二芯层（2）的折射率最大。该波导结构能够有效调控OAM轨道角动量不同模式输出，模式间有效折射率差大于2×10 ‑4，模式容易分离，便于复用与解复用。波导OAM轨道角动量纯度高，模式间串扰小，适合光纤通信SDM空分复用系统的长距离传输，能够满足400G高速传输系统需求。

Description

抗弯曲低串扰光子轨道角动量光纤波导 技术领域
本发明涉及光纤通信领域的一种空分复用新型光波导，尤其涉及一种抗弯曲低串扰光子轨道角动量(OAM)光纤。
背景技术
为了便于理解，本发明涉及的专业术语如下：
OAM:轨道角动量(Orbital Angular Momentum)，轨道角动量表示电子绕传播轴旋转，是由能量流(由坡印廷矢量描述)围绕光轴旋转而产生的，它使电磁波的相位波前呈涡旋状。
SAM：自旋角动量(Spin Angular Momentum)，自旋角动量仅与光子的自旋有关，表现为圆偏振状态。
折射率剖面(RIP)：光纤或光纤预制棒(包括芯棒)的折射率与其半径之间的关系曲线。
环形芯渐变折射率剖面分布函数：
Figure PCTCN2023070373-appb-000001
其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
Figure PCTCN2023070373-appb-000002
n为折射率，n 1一般情况为芯中间的折射率，n 2一般情况为包层或者边缘折射率，r 1和r 2分别为不同折射率层n 1层和n 2层的半径，g为折射率剖面分布参数。
WDM:波分复用(Wavelength Division Multiplexing)
QAM:正交振幅调制(Quadrature Amplitude Modulation)
QPSK:正交相移键控(Quadrature Phase Shift Keying)
MIMO:多输入多输出(Multiple-Input Multiple-Out-put)
SDM:空分复用(Space Division Multiplexing)
香农极限(Shannon limit)：通信信道的香农极限或香农容量(Shannon capacity)是针对特定噪声水平的信道的理论最大信息传输速率。著名的香农定理用公式给出:C＝B×log2(1+S/N)，其中C是可得到的链路速度(信道容量)，B是链路的带宽，S是平均信号功率，N是平均噪声功率，信噪比(S/N)通常用分贝(dB)表示，分贝数＝10×lg(S/N)。
量子隧穿效应(QTE)：量子隧穿效应(Quantum tunnelling effect)为一种量子特性，像电子等微观粒子能够穿入或穿越位势垒的量子行为，尽管位势垒的高度大于粒子的总能量。根据量子力学，微观粒子具有波的性质，而有不为零的机率穿过势障壁。
从光纤通信容量发展趋势来看，基于目前广泛采用的波分复用(WDM)及各种高级调 制技术(QAM、QPSK等)，现有光纤通信系统已经逼近并很快将达到标准单模光纤(SMF)传输容量的ShannonLimit(香农极限)。5G(第5代移动通信)使用的低频频段，与我们现在用的4G(第4代移动通信)没有本质差异，主要是通过多输入与多输出技术(MIMO)，非正交复用技术(NOMA)来提升信道的容量。到了6G阶段，由于5G技术已经逼近“香农极限”，所以会采取提升信道带宽的方式，而信道的带宽核心在于“信息承载的媒质—光纤材料”。5G传输的数据爆炸式增长，6G面临许多新的传输难题，如何突破传输容量瓶颈已迫在眉睫。
从近年来针对提升光纤通信容量的研究进展来看，利用光纤的高阶矢量模式--光子轨道角动量(OAM)作为新的维度进行空分复用(SDM)，已经成为光纤通信领域的研究和应用热点方向。OAM光子轨道角动量光纤可以携带光子轨道角动量信息，从科学理论角度可以推论，轨道角动量的拓扑电荷数可以无限拓展，可有效地扩充光通信复用规模。光子不但具有沿传播方向纵向的线动量，同时还拥有与光偏振特性相关的角动量，即自旋角动量(SAM)。而OAM不同于SAM，OAM光束拥有与角向位相分布相关的位相结构，因而携带了轨道角动量。光子轨道角动量OAM对应无穷多个本征值，理论上可以构建Hilbert无限维空间，具有无穷多个本征模态，各模式之间相互正交，光子的轨道角动量为光子带来了一个全新的自由度，在利用光子进行经典或量子信息处理时，可以制备出光子自旋、轨道角动量纠缠实现高维量子信息系统在光通信中，可以用于承载信息可提高通信系统的数据容量，在高数据容量通信系统具有优良的优势，可实现高容量、高速率、大规模的光通信网络组网。
在目前的光纤通信领域，由于现网中广泛使用的是单模光纤传输，而传统单模光纤支持的传输模式必须是基模，具有螺旋相位波前的OAM波在单模光纤中传输是会由于模式简单简并退化成平面波，因此需要特殊设计结构的光纤传输OAM信道。2013年，美国Boston University大学Alan E.Willner团队利用特殊设计的光纤来传输OAM光束[Nenad Bozinovic,Siddharth Ramachandran.Terabit-scale orbital angular momentum mode division multiplexing in fibers[J].Science,2013,340(6140):1545-1548]，实现了1.6Tbit/s的光信息传输，传输光纤长为1.1km，这项研究为未来基于OAM的光通信技术的光纤传输提供了可能性。近年来，利用光子轨道角动量维度进行空分复用通信的研究成为大容量通信领域的研究热点。
然而，实际上OAM光束除了在传输过程中会引发光束尺寸变大、模式串扰等新问题，其固有的一些属性也会给接收端孔径适配，以及接收端检测到OAM值的准确分类带来挑 战。另一方面，OAM光束的产生方法也面临挑战，OAM光束主要分为在空间中生成和在光纤中生成。在空间中生成OAM模式光束有两种方法：第一种方法利用激光器直接输出OAM光束，这是腔内产生的方式，在激光器腔内对激光束进行调制产生OAM光束，但产生这种OAM光束的生成成本较高，OAM模式稳定性容易受到影响，而且OAM模式纯度低；第二种为利用空间结构器件，但是器件较多，结构复杂，同样面临OAM模式稳定性与模式纯度的问题；第三种方法则是在光纤中生成与传输，在光纤中产生的方法既简化了光学结构，且相位纯度更高，OAM光束通过对应光纤中相应阶数矢量模式的叠加得到，其相位纯度更高。为此，各国科学家纷纷开展能够产生优良OAM模式的波导结构研究。
美国专利US20190170933A1提出了一种用于多模照明的光学成像用涡旋光纤，该光纤能够产生两阶OAM模式，主要用于产生圆形光束用于照明，传输距离短，不适合通信领域应用。
世界专利WO2017210679A1提出了一种制造涡旋光纤的系统和方法，该方法没有明确提出涡旋光纤的结构参数以及OAM模式特性。
美国专利US8948559B2提出了一种空分复用的多线性偏振模光纤，该光纤纤芯为渐变抛物线型的折射率分布，通过降低纤芯相对折射率差到0.8％，获得了2到4个少模，并可以降低瑞利散射损耗，该专利没有明确其OAM模式的特征与性能参数。
美国专利US8705922B2提出了一种四模光纤，该光纤纤芯为高折射率，纤芯折射率剖面为抛物线分布，抛物线剖面参数g值在1.9到2.1，在1550nm波长的DGD时延为150ps/km，该专利没有明确其OAM模式的特征与性能参数。
中国专利CN110297288A提出了一种低衰减阶跃型轨道角动量光纤，其波导结构复杂，并且需要控制好折射率的分布，制造方法苛刻，实现难度大，而且模式串扰需要进一步提升。
中国专利CN110333572A提出了一种低衰减渐变型轨道角动量光纤，该光纤波导结构与CN110297288A基本相似，在环形部分的凹陷进行了折射率渐变，这种结构实施较为困难，而且模式串扰需要进一步提升。
中国专利CN108680990A提出了一种环形芯轨道角动量光纤，但是其衰耗大于1dB/km，适合短距离传输；中国专利CN106338793A提出了一种环形芯光纤可以抑制一些容易耦合的高阶模式，但是其衰减达到0.31dB/km，与低损耗衰减指标仍然有一定的距离。
中国专利CN105242347A提出了一种高纯度、低本征串扰的轨道角动量传输光纤，该光纤纤芯折射率剖面采用抛物线分布，折射率分布参数g值大于2.1，而且纤芯相对包层中的 折射差达到0.10，在通信光纤石英体系实现难度大，模式串扰难于控制，衰减难以降低达到远距离传输的要求。
发明内容
本发明要解决的技术问题是：综上所述，传统光纤以及报道的发明专利不能够很好地解决大容量空分复用光纤通信系统领域对光子轨道角动量OAM信道传输发展的需求，本发明为解决下一代光纤通信系统空分复用技术的实用化重大需求，提出了一种抗弯曲低串扰光子轨道角动量光纤波导。该光纤波导在1530nm到1565nm波长范围内可以调控4个不同阶的光子轨道角动量OAM模式，抗弯曲能力强，模式易于分离并且模式间串扰低，该波导结构适合规模化生产，并能够应用于长距离光纤通信系统的稳定传输。
本发明的技术方案是：
一种抗弯曲低串扰光子轨道角动量光纤波导,光纤从中心向外依次为第一芯层、第二芯层、第一包层、第二包层、和第三包层，第三包层最厚，第一芯层次之，第一包层最薄；第一包层的折射率最小，第二包层次之，第二芯层的折射率最大。
第一芯层半径r 1和第二芯层半径r 2的满足关系函数关系A＝k 1×10×log(r 2/r 1)/(L-2),k 1取值范围为0.36-1.52，L取值范围为3到9的正整数，A的范围为0.06446到1.61151。
第一包层半径r 3与第二芯层半径r 2满足函数关系B＝k 2×10×log(r 3/r 2)×(L-2),k 2的取值范围为0.66-1.37，L取值范围为2到9的正整数，B的范围为0到3.4649。
第一芯层折射率n 1与第三包层折射率n 5的折射率差在-0.00029到-0.01603。
第二芯层折射率n 2与第三包层折射率n 5的折射率差在0.017485到0.037885。第一包层
折射率n 3与第三包层折射率n 5的折射率差在-0.005到-0.0153。
第二包层折射n 4与第三包层折射率n 5的折射率差在-0.005到-0.0153。
第二芯层折射率n 2的折射率曲线渐变并且满足折射率剖面分布函数：
Figure PCTCN2023070373-appb-000003
其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
Figure PCTCN2023070373-appb-000004
g为折射率剖面分布参数，g值在-2到9之间。
g的取值为-2、-3、2、3或5。
该光纤在1530nm到1565nm波长范围内可以调控4个不同阶的OAM模式输出实现稳定传输，OAM-0阶、OAM-±1阶、OAM-±2阶和OAM-±3阶，各个OAM模式之间的有效折射率差大于1.52×10 -4。
光纤各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗 小于或等于0.50dB；光纤OAM-0阶与OAM-±1阶模式之间的串扰小于-9dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-16dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-15dB/80km，OAM-±1阶与OAM-±3阶模式之间的串扰小于-25dB/80km。
本发明的有益效果：
(1)本发明波导结构能够有效调控OAM轨道角动量不同模式输出，模式间有效折射率差大于2×10 -4，模式容易分离，便于复用与解复用。
(2)本发明波导具备良好的抗弯曲能力，各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗小于或等于0.50dB，弯曲附加损耗小，能够适应弯曲等复杂应用环境，提升应用的可靠性。
(3)本发明波导OAM轨道角动量纯度高，模式间串扰小，适合光纤通信SDM空分复用系统的长距离传输，能够满足400G高速传输系统需求，具有较好的应用前景和经济社会效益。
(4)本发明波导结构稳定，易于实现，能够提高生产效率，适合大规模化生产。
附图说明
为了更清楚地说明本发明实施例的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，应当理解，以下附图仅示出了本发明的某些实施例，因此不应被看作是对范围的限定，对于本领域普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图获得其他相关的附图。
在结合以下附图阅读本公开的实施例的详细描述之后，能够更好地理解本发明的上述特征和优点。在附图中，各组件不一定是按比例绘制，并且具有类似的相关特性或特征的组件可能具有相同或相近的附图标记。
图1是本发明光纤波导的折射率剖面结构示意图；
图2是本发明光纤波导端面结构的示意图。
其中：1-第一芯层，2-第二芯层，3-第一包层，4-第二包层，5-第三包层，6-内涂层，7-外涂层
具体实施方式
以下结合附图和具体实施例对本发明作详细描述，以下结合附图和具体实施例描述的诸方面仅是示例性的，而不应被理解为对本发明的保护范围进行任何限制。
参加附图1和图2所示，本发明提供一种光子轨道角动量(OAM)光纤波导，该光纤 波导由两个芯层和三个包层及涂覆层组成，其特征在于：从中心向外依次为第一芯层(r 1)、第二芯层(r 2)、第一包层(r 3)、第二包层(r 4)、第三包层(r 5)组成，以及在第三包层外的涂覆层组成，其涂覆层由内涂层(图2中的6)和外涂层(图2中的7)组成。第三包层最厚，第一芯层次之，第一包层最薄；第一包层的折射率最小，第二包层次之，第二芯层的折射率最大。
所述第一芯层半径r 1和第二芯层半径r 2的满足关系函数关系A＝k 1×10×log(r 2/r 1)/(L-2),k 1取值范围为0.36-1.52，L取值范围为3到9的正整数，A的范围为0.06446到1.61151；第一包层半径r 3与第二芯层半径r 2满足函数关系B＝k 2×10×log(r 3/r 2)×(L-2),k 2的取值范围为0.66-1.37，L取值范围为2到9的正整数，B的范围为0到3.4649。第一芯层折射率n 1与第三包层折射率n 5的折射率差在-0.00029到-0.01603。第二芯层折射率n 2与第三包层折射率n 5的折射率差为0.017485。第一包层折射率n 3与第三包层折射率n 5的折射率差在-0.005到-0.0153，该包层波导结构具有量子隧穿效应，可以调控模式的损耗特性；第二包层折射n 4与第三包层折射率n 5的折射率差在-0.005到-0.0153。第二芯层的环形芯渐变折射率剖面分布函数公式
Figure PCTCN2023070373-appb-000005
其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
Figure PCTCN2023070373-appb-000006
g为折射率剖面分布参数，第二芯层折射率n 2的折射率曲线渐变并且满足该折射率剖面分布函数，其折射率剖面分布参数g值在-2到9之间，优选g＝-2,-3,2,3,5。该光子轨道角动量光纤波导在1530nm到1565nm波长范围内可以调控4个不同阶的OAM模式输出实现稳定传输，OAM-0阶、OAM-±1阶、OAM-±2阶和OAM-±3阶，各个OAM模式之间的有效折射率差大于1.52×10 -4。该光子轨道角动量光纤波导各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗小于或等于0.50dB。该光子轨道角动量光纤波导OAM-0阶与OAM-±1阶模式之间的串扰小于-9dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-16dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-15dB/80km，OAM-±1阶与OAM-±3阶模式之间的串扰小于-25dB/80km。
实施实例一：
本发明提供一种光子轨道角动量(OAM)光纤波导，该光纤波导由两个芯层和三个包层及涂覆层组成，其特征在于：从中心向外依次为第一芯层(r 1)、第二芯层(r 2)、第一包层(r 3)、第二包层(r 4)、第三包层(r 5)组成，以及在第三包层外的内涂层和外涂层组成，该涂覆层采用有机树脂固化经过紫外光固化而成。所述第一芯层半径r 1和第二芯层半径r 2 的满足关系函数关系A＝k 1×10×log(r 2/r 1)/(L-2),k 1为0.36，A为0.06446，L取值范围为3到9的正整数；第一包层半径r 3与第二芯层半径r 2满足函数关系B＝k 2×10×log(r 3/r 2)×(L-2),k 2为0.66，B为0.3131，L取值范围为2到9的正整数。第一芯层折射率n 1与第三包层折射率n 5的折射率差为-0.00029。第二芯层折射率n 2与第三包层折射率n 5的折射率差为0.017485。第一包层折射率n 3与第三包层折射率n 5的折射率差为-0.005，该包层波导结构具有量子隧穿效应，可以调控模式的损耗特性；第二包层折射n 4与第三包层折射率n 5的折射率差为-0.00。第二芯层的环形芯渐变折射率剖面分布函数公式
Figure PCTCN2023070373-appb-000007
其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
Figure PCTCN2023070373-appb-000008
g为折射率剖面分布参数，第二芯层折射率n 2的折射率曲线渐变并且满足该折射率剖面分布函数，其折射率剖面分布参数g值为-2。该光子轨道角动量光纤波导在1530nm到1565nm波长范围内可以调控4个不同阶的OAM模式输出实现稳定传输，OAM-0阶、OAM-±1阶、OAM-±2阶和OAM-±3阶，各个OAM模式之间的有效折射率差大于1.53×10 -4(见表1)。该光子轨道角动量光纤波导各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗小于或等于0.50dB(见表1)。该光子轨道角动量光纤波导OAM-0阶与OAM-±1阶模式之间的串扰小于-9dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-16dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-15dB/80km，OAM-±1阶与OAM-±3阶模式之间的串扰小于-25dB/80km(见表1)。
实施实例二：
本发明提供一种光子轨道角动量(OAM)光纤波导，该光纤波导由两个芯层和三个包层及涂覆层组成，其特征在于：从中心向外依次为第一芯层(r 1)、第二芯层(r 2)、第一包层(r 3)、第二包层(r 4)、第三包层(r 5)组成，以及在第三包层外的涂覆层组成。所述第一芯层半径r 1和第二芯层半径r 2的满足关系函数关系A＝k 1×10×log(r 2/r 1)/(L-2),k 1为1.52，A为1.61151，L取值范围为3到9的正整数；第一包层半径r 3与第二芯层半径r 2满足函数关系B＝k 2×10×log(r 3/r 2)×(L-2),k 2为1.37，B为3.4649，L取值范围为2到9的正整数。第一芯层折射率n 1与第三包层折射率n 5的折射率差为-0.01603。第二芯层折射率n 2与第三包层折射率n 5的折射率差为0.037885。第一包层折射率n 3与第三包层折射率n 5的折射率差为-0.0153，该包层波导结构具有量子隧穿效应，可以调控模式的损耗特性；第二包层折射n 4与第三包层折射率n 5的折射率差为-0.0153。第二芯层的环形芯渐变折射率剖面分布函数公式
Figure PCTCN2023070373-appb-000009
其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
Figure PCTCN2023070373-appb-000010
g为折射率剖面分布参数，第二芯层折射率n 2的折射率曲线渐变并且满足该折射率剖面分布函数，其折射率剖面分布参数g值为-3。该光子轨道角动量光纤波导在1530nm到1565nm波长范围内可以调控4个不同阶的OAM模式输出实现稳定传输，OAM-0阶、OAM-±1阶、OAM-±2阶和OAM-±3阶，各个OAM模式之间的有效折射率差大于1.52×10 -4(见表1)。该光子轨道角动量光纤波导各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗小于或等于0.37dB(见表1)。该光子轨道角动量光纤波导OAM-0阶与OAM-±1阶模式之间的串扰小于-9dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-16dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-15dB/80km，OAM-±1阶与OAM-±3阶模式之间的串扰小于-25dB/80km(见表1)。
实施实例三：
本发明提供一种光子轨道角动量(OAM)光纤波导，该光纤波导由两个芯层和三个包层及涂覆层组成，其特征在于：从中心向外依次为第一芯层(r 1)、第二芯层(r 2)、第一包层(r 3)、第二包层(r 4)、第三包层(r 5)组成，以及在第三包层外的涂覆层组成。所述第一芯层半径r 1和第二芯层半径r 2的满足关系函数关系A＝k 1×10×log(r 2/r 1)/(L-2),k 1为1.01，A为0.8057,L取值范围为3到9的正整数；第一包层半径r 3与第二芯层半径r 2满足函数关系B＝k 2×10×log(r 3/r 2)×(L-2),k 2为1.12，B为0.6281，L取值范围为3到9的正整数。第一芯层折射率n 1与第三包层折射率n 5的折射率差为-0.00949。第二芯层折射率n 2与第三包层折射率n 5的折射率差位0.029146。第一包层折射率n 3与第三包层折射率n 5的折射率差为-0.01093，该包层波导结构具有量子隧穿效应，可以调控模式的损耗特性；第二包层折射n 4与第三包层折射率n 5的折射率差为-0.00729。第二芯层的环形芯渐变折射率剖面分布函数公式
Figure PCTCN2023070373-appb-000011
其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
Figure PCTCN2023070373-appb-000012
g为折射率剖面分布参数，第二芯层折射率n 2的折射率曲线渐变并且满足该折射率剖面分布函数，其折射率剖面分布参数g值为9。该光子轨道角动量光纤波导在1530nm到1565nm波长范围内可以调控4个不同阶的OAM模式输出实现稳定传输，OAM-0阶、OAM-±1阶、OAM-±2阶和OAM-±3阶，各个OAM模式之间的有效折射率差大于1.52×10 -4(见表1)。该光子轨道角动量光纤波导各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗小于或等于0.43dB(见表1)。该光子轨道角动量光纤波导 OAM-0阶与OAM-±1阶模式之间的串扰小于-9dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-16dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-15dB/80km，OAM-±1阶与OAM-±3阶模式之间的串扰小于-25dB/80km(见表1)。
实施实例四：
本发明提供一种光子轨道角动量(OAM)光纤波导，该光纤波导由两个芯层和三个包层及涂覆层组成，其特征在于：从中心向外依次为第一芯层(r 1)、第二芯层(r 2)、第一包层(r 3)、第二包层(r 4)、第三包层(r 5)组成，以及在第三包层外的涂覆层组成。所述第一芯层半径r 1和第二芯层半径r 2的满足关系函数关系A＝k 1×10×log(r 2/r 1)/(L-2),k 1为0.96，A为0.5371，L取值范围为3到9的正整数；第一包层半径r 3与第二芯层半径r 2满足函数关系B＝k 2×10×log(r 3/r 2)×(L-2),k 2为0.987，B为0.9422，L取值范围为2到9的正整数。第一芯层折射率n 1与第三包层折射率n 5的折射率差为-0.01392。第二芯层折射率n 2与第三包层折射率n 5的折射率差为0.032056。第一包层折射率n 3与第三包层折射率n 5的折射率差为-0.011953，该包层波导结构具有量子隧穿效应，可以调控模式的损耗特性；第二包层折射n 4与第三包层折射率n 5的折射率差位-0.009651。第二芯层的环形芯渐变折射率剖面分布函数公式
Figure PCTCN2023070373-appb-000013
其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
Figure PCTCN2023070373-appb-000014
g为折射率剖面分布参数，第二芯层折射率n 2的折射率曲线渐变并且满足该折射率剖面分布函数，其折射率剖面分布参数g值为2。该光子轨道角动量光纤波导在1530nm到1565nm波长范围内可以调控4个不同阶的OAM模式输出实现稳定传输，OAM-0阶、OAM-±1阶、OAM-±2阶和OAM-±3阶，各个OAM模式之间的有效折射率差大于1.52×10 -4(见表1)。该光子轨道角动量光纤波导各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗小于或等于0.45dB(见表1)。该光子轨道角动量光纤波导OAM-0阶与OAM-±1阶模式之间的串扰小于-9dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-16dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-15dB/80km，OAM-±1阶与OAM-±3阶模式之间的串扰小于-25dB/80km(见表1)。
实施实例五：
本发明提供一种光子轨道角动量(OAM)光纤波导，该光纤波导由两个芯层和三个包层及涂覆层组成，其特征在于：从中心向外依次为第一芯层(r 1)、第二芯层(r 2)、第一包层(r 3)、第二包层(r 4)、第三包层(r 5)组成，以及在第三包层外的涂覆层组成。所述第一芯层半径r 1和第二芯层半径r 2的满足关系函数关系A＝k 1×10×log(r 2/r 1)/(L-2),k 1为1.12，A为 0.3223，L取值范围为3到9的正整数；第一包层半径r 3与第二芯层半径r 2满足函数关系B＝k 2×10×log(r 3/r 2)×(L-2),k 2为1.32，L为2，B为0。第一芯层折射率n 1与第三包层折射率n 5的折射率差为-0.01506。第二芯层折射率n 2与第三包层折射率n 5的折射率差为0.027399。第一包层折射率n 3与第三包层折射率n 5的折射率差为0；第二包层折射n 4与第三包层折射率n 5的折射率差为-0.00939。第二芯层的环形芯渐变折射率剖面分布函数公式
Figure PCTCN2023070373-appb-000015
其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
Figure PCTCN2023070373-appb-000016
g为折射率剖面分布参数，第二芯层折射率n 2的折射率曲线渐变并且满足该折射率剖面分布函数，其折射率剖面分布参数g值为5。该光子轨道角动量光纤波导在1530nm到1565nm波长范围内可以调控4个不同阶的OAM模式输出实现稳定传输，OAM-0阶、OAM-±1阶、OAM-±2阶和OAM-±3阶，各个OAM模式之间的有效折射率差大于1.52×10 -4(见表1)。该光子轨道角动量光纤波导各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗小于或等于0.45dB(见表1)。该光子轨道角动量光纤波导OAM-0阶与OAM-±1阶模式之间的串扰小于-9dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-16dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-15dB/80km，OAM-±1阶与OAM-±3阶模式之间的串扰小于-25dB/80km(见表1)。
实施实例六：
本发明提供一种光子轨道角动量(OAM)光纤波导，该光纤波导由两个芯层和三个包层及涂覆层组成，其特征在于：从中心向外依次为第一芯层(r 1)、第二芯层(r 2)、第一包层(r 3)、第二包层(r 4)、第三包层(r 5)组成，以及在第三包层外的涂覆层组成。所述第一芯层半径r 1和第二芯层半径r 2的满足关系函数关系A＝k 1×10×log(r 2/r 1)/(L-2),k 1为0.837，A为0.16115，L取值范围为3到9的正整数；第一包层半径r 3与第二芯层半径r 2满足函数关系B＝k 2×10×log(r 3/r 2)×(L-2),k 2为0.763，B为2.9185，L取值范围为2到9的正整数。第一芯层折射率n 1与第三包层折射率n 5的折射率差为-0.01039。第二芯层折射率n 2与第三包层折射率n 5的折射率差为0.035065。第一包层折射率n 3与第三包层折射率n 5的折射率差为-0.00796，该包层波导结构具有量子隧穿效应，可以调控模式的损耗特性；第二包层折射n 4与第三包层折射率n 5的折射率差为-0.00856。第二芯层的环形芯渐变折射率剖面分布函数公式
Figure PCTCN2023070373-appb-000017
其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
Figure PCTCN2023070373-appb-000018
g为折射率剖面分布参数，第二芯层折射率n 2的折射率曲线渐变并且满足该折射 率剖面分布函数，其折射率剖面分布参数g值为3。该光子轨道角动量光纤波导在1530nm到1565nm波长范围内可以调控4个不同阶的OAM模式输出实现稳定传输，OAM-0阶、OAM-±1阶、OAM-±2阶和OAM-±3阶，各个OAM模式之间的有效折射率差大于1.52×10 -4(见表1)。该光子轨道角动量光纤波导各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗小于或等于0.46dB(见表1)。该光子轨道角动量光纤波导OAM-0阶与OAM-±1阶模式之间的串扰小于-9dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-16dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-15dB/80km，OAM-±1阶与OAM-±3阶模式之间的串扰小于-25dB/80km(见表1)。
以上实施示例光纤波导的主要性能指标见表1。
表1 实施示例光纤波导的主要性能指标
Figure PCTCN2023070373-appb-000019
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。
提供对本公开的先前描述是为使得本领域任何技术人员皆能够制作或使用本公开。对本公开的各种修改对本领域专业技术人员来说都将是显而易见的，且本文中所定义的普适原理可被应用到其他变体而不会脱离本公开的精神或范围。由此，本公开并非旨在被限定于本文中所描述的示例和设计，而是应被授予与本文中所公开的原理和新颖性特征相一致的最广范围。
以上所述仅为本申请的较佳实例而已，并不用以限制本申请，凡在本申请的精神和原则 之内，所做的任何修改、等同替换、改进等，均应包含在本申请保护的范围之内。

Claims (10)

  1. 一种抗弯曲低串扰光子轨道角动量光纤波导,其特征在于光纤从中心向外依次为第一芯层、第二芯层、第一包层、第二包层、和第三包层，其中：第三包层最厚，第一芯层次之，第一包层最薄；第一包层的折射率最小，第二包层次之，第二芯层的折射率最大。
  2. 根据权利要求1所述的抗弯曲低串扰光子轨道角动量光纤波导,其特征在于：第一芯层半径r 1和第二芯层半径r 2的满足关系函数关系A＝k 1×10×log(r 2/r 1)/(L-2),k 1取值范围为0.36-1.52，L取值范围为3到9的正整数，A的范围为0.06446到1.61151。
  3. 根据权利要求1所述的抗弯曲低串扰光子轨道角动量光纤波导,其特征在于：第一包层半径r 3与第二芯层半径r 2满足函数关系B＝k 2×10×log(r 3/r 2)×(L-2),k 2的取值范围为0.66-1.37，L取值范围为2到9的正整数，B的范围为0到3.4649。
  4. 根据权利要求1所述的抗弯曲低串扰光子轨道角动量光纤波导,其特征在于：第一芯层折射率n 1与第三包层折射率n 5的折射率差在-0.00029到-0.01603。
  5. 根据权利要求1所述的抗弯曲低串扰光子轨道角动量光纤波导,其特征在于：第二芯层折射率n 2与第三包层折射率n 5的折射率差在0.017485到0.037885。
  6. 根据权利要求1所述的抗弯曲低串扰光子轨道角动量光纤波导,其特征在于：第一包层折射率n 3与第三包层折射率n 5的折射率差在-0.005到-0.0153；第二包层折射n 4与第三包层折射率n 5的折射率差在-0.005到-0.0153。
  7. 根据权利要求1所述的抗弯曲低串扰光子轨道角动量光纤波导,其特征在于第二芯层折射率n 2的折射率曲线渐变并且满足折射率剖面分布函数：
    Figure PCTCN2023070373-appb-100001
    其中r 1≤r≤r 2，r a＝(r 1+r 2)/2，d＝r 2-r 1，
    Figure PCTCN2023070373-appb-100002
    g为折射率剖面分布参数，g值在-2到9之间。
  8. 根据权利要求7所述的抗弯曲低串扰光子轨道角动量光纤波导,其特征在于：g的取值为-2、-3、2、3或5。
  9. 根据权利要求1-8任一项所述的抗弯曲低串扰光子轨道角动量光纤波导,其特征在于：该光纤在1530nm到1565nm波长范围内可以调控4个不同阶的OAM模式输出实现稳定传输，OAM-0阶、OAM-±1阶、OAM-±2阶和OAM-±3阶，各个OAM模式之间的有效折射率差大于1.52×10 -4。
  10. 根据权利要求9所述的抗弯曲低串扰光子轨道角动量光纤波导,其特征在于：光纤各个OAM模式在1550nm波长处的弯曲损耗小，R5mm弯曲1圈的宏弯损耗小于或等于0.50dB；光纤OAM-0阶与OAM-±1阶模式之间的串扰小于-9dB/80km，OAM-±1阶与 OAM-±2阶模式之间的串扰小于-16dB/80km，OAM-±1阶与OAM-±2阶模式之间的串扰小于-15dB/80km，OAM-±1阶与OAM-±3阶模式之间的串扰小于-25dB/80km。
PCT/CN2023/070373 2022-01-20 2023-01-04 抗弯曲低串扰光子轨道角动量光纤波导 WO2023138370A1 (zh)

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