Chiral multi-dimensional multi-band controllable OAM beam generator and preparation method thereof

Abstract

The present invention discloses a chiral multi-dimensional, multi-band controllable OAM beam generator, comprising a laser light source and a multi-core twisted optical fiber. The core of the multi-core twisted optical fiber has a certain twist rate. Light from the laser light source enters the multi-core twisted optical fiber, where the central core and adjacent cores couple to each other, enabling the central core to selectively couple with a specific "satellite core" over a wide wavelength range, thereby exciting the higher-order modes of the "satellite core." Because the twisted higher-order modes transform from scalar modes to vector modes, carrying orbital angular momentum, the selective coupling of the central core of the twisted optical fiber with the "satellite core" excites multiple orbital angular momentum modes of the "satellite cores," thereby generating a multi-dimensional, multi-band OAM beam. By varying the twist rate of the twisted optical fiber, the wavelength of the light, and the distance between the cores, the central core can selectively couple with a specific "satellite core," achieving flexible selection of the excitation OAM beam.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber communications and functional devices, and in particular to a chiral multi-dimensional multi-band controllable OAM light beam generator and a preparation method thereof. Background Art

[0002] Over the past three decades, the data carrying capacity of single-mode optical fibers has increased by four orders of magnitude. As the capacity of current optical fiber systems reaches its limit, OAM (Orbital Angular Momentum) optical communication technology, which theoretically has infinite high-order multiplexing dimensions, has become one of the research hotspots in the field of ultra-high-speed optical communications to break through the Shannon limit.

[0003] Although some reports have demonstrated the transmission of OAM channels over 1 km in specialized optical fibers, these systems consist of discrete optical diffraction devices. The fiber-to-free-space and free-space-to-fiber coupling processes inevitably introduce unnecessary insertion loss. Furthermore, the systems are complex and bulky, with limited flexibility and stability, difficulty adjusting, and inadequate integration. Therefore, directly generating OAM beams in optical fibers has become a research challenge. Initial attempts have focused on generating OAM beams using traditional fiber Bragg gratings (FBGs). However, this approach, based on the high cost of grating writing and the resulting OAM beams from the coupling and superposition of modes, suffer from poor quality and instability. Consequently, in 2011, Bozinovic et al. first proposed a 0.9 km helical fiber for dual OAM state photon transmission. This approach reduced fabrication costs and complexity. In 2019, Wang Yiping et al. reported an OAM-generating device in a helical photonic crystal fiber with a standard regular hexagonal arrangement, demonstrating that the cladding can generate first-order OAM beams. However, the spiral photonic crystal fibers reported so far are basically single-core structures, and the generated OAM orbital angular momentum is located in the cladding, resulting in large transmission losses. Summary of the Invention

[0004] In view of this, and in order to solve the above-mentioned problems in the prior art, the present invention proposes a chiral multi-dimensional, multi-band controllable OAM beam generator and a preparation method thereof, which utilizes the principle of chiral multi-core fiber coupling to generate multi-band, multi-controllable OAM beams. It can not only spontaneously generate and transmit OAM beams, but also flexibly control light to produce specific high-order modes in specific bands at specific locations.

[0005] The present invention solves the above problems through the following technical means:

[0006] In one aspect, the present invention provides a chiral multi-dimensional multi-band controllable OAM beam generator, comprising a laser light source and a multi-core twisted optical fiber;

[0007] The light from the laser source enters the multi-core twisted fiber. The middle core of the multi-core twisted fiber couples with the adjacent cores to achieve selective coupling with a specific "satellite core" within a wide wavelength range, thereby exciting the high-order modes of the "satellite core".

[0008] Since the distances from the satellite core to the center of the fiber are different, and the distances from the edge of the satellite core to the edge of the middle core are different, the satellite core is affected by the twist differently, which in turn affects the refractive index of the satellite core differently. Furthermore, the diameters of the satellite cores are different. Therefore, under multiple influencing factors, in different wavelength bands, the fundamental mode of the middle core selectively couples with a specific satellite core, thereby generating a specific high-order mode of the specific satellite core.

[0009] Because the twisted high-order mode changes from a scalar mode to a vector mode and carries orbital angular momentum, the orbital angular momentum modes of multiple "satellite cores" are excited by selective coupling between the middle core of the twisted optical fiber and the "satellite core", thereby realizing the generation of multi-dimensional and multi-band OAM beams.

[0010] Furthermore, the chiral multi-dimensional multi-band controllable OAM beam generator further comprises a single-mode optical fiber, and the light of the laser light source enters the multi-core twisted optical fiber through the single-mode optical fiber;

[0011] The core of the single-mode fiber is coaxial with the core of the multi-core twisted fiber;

[0012] The diameter of the middle core of the multi-core twisted optical fiber matches the diameter of the core of the single-mode optical fiber to facilitate optical fiber fusion splicing;

[0013] The diameter of the multi-core twisted optical fiber cladding matches the diameter of the single-mode optical fiber cladding to facilitate optical fiber fusion splicing.

[0014] Furthermore, a cladding is added around at least one of the "guard cores" in the multi-core twisted optical fiber, and its refractive index is lower than that of the respective "guard core" but higher than that of the cladding of the entire optical fiber.

[0015] Furthermore, the multi-core twisted optical fiber has three cores, four cores or five cores.

[0016] Furthermore, the diameter of the "guard core" of the multi-core twisted optical fiber is 12-15 μm.

[0017] Furthermore, the refractive index of the middle core of the multi-core twisted optical fiber is 1.44-1.48; the refractive index of the "guard core" of the multi-core twisted optical fiber is smaller than that of the middle core, and the refractive index of the "guard core" of the multi-core twisted optical fiber is 1.42-1.46.

[0018] Furthermore, the distance between the "satellite cores" of the multi-core twisted optical fiber is greater than the distance from the middle core to the "satellite core", and the distance between the "satellite core" and the middle core of the multi-core twisted optical fiber is 13-18 μm.

[0019] Furthermore, the twist rate of the multi-core twisted optical fiber is 2000 rad / m-2300 rad / m; the twist length of the multi-core twisted optical fiber is 2800 μm-3000 μm.

[0020] Furthermore, the core diameter of the single-mode optical fiber is 9-11 μm; the cladding diameter of the single-mode optical fiber is 124-126 μm; the coating diameter of the single-mode optical fiber is 249-251 μm; and the refractive index of the core of the single-mode optical fiber is 1.44-1.48.

[0021] In another aspect, the present invention provides a method for preparing the chiral multi-dimensional multi-band controllable OAM beam generator, comprising:

[0022] S1. Arrange the fiber cores by stacking method, and then prepare multi-core optical fiber by drawing;

[0023] S2. heating the prepared multi-core optical fiber to make it soft, applying a twisting force to the multi-core optical fiber to twist it, thereby obtaining a twisted multi-core optical fiber;

[0024] S3. Use a fiber fusion splicer to fusion-splice single-mode optical fibers, twisted multi-core optical fibers, and pigtails of laser light sources.

[0025] Compared with the prior art, the beneficial effects of the present invention include at least:

[0026] 1. The present invention can successfully couple the middle core of a multi-core twisted optical fiber with the adjacent "satellite core" by transmitting light on the middle core of the multi-core twisted optical fiber, thereby coupling the middle core with a specific "satellite core" over a wider wavelength range and achieving the excitation of specific high-order modes of the "satellite core".

[0027] 2. The twisted fiber's high-order modes change from scalar to vector modes, carrying orbital angular momentum. Coupling the intermediate fiber core with the satellite core can excite specific orbital angular momentum modes in that satellite core, enabling the generation of multi-dimensional, multi-band OAM beams with more channels and orders.

[0028] 3. By varying the twist rate of the twisted fiber, the wavelength of light, and the distance between the cores, the central core can be selectively coupled to a specific satellite core, achieving flexible selection of the excitation OAM beam.

[0029] 4. The specific high-order modes generated by this OAM beam generator are relatively independent and pure, solving the problem of impure high-order modes generated in the same fiber core. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. 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 creative work.

[0031] Figure 1 Schematic diagram of the structure of the chiral multi-dimensional multi-band controllable OAM beam generator of the present invention;

[0032] Figure 2 Schematic diagram of the structure of the chiral multi-dimensional multi-band controllable OAM beam generator (including single-mode optical fiber) of the present invention;

[0033] Figure 3 A schematic diagram of the twisting of a three-core optical fiber according to the present invention;

[0034] Figure 4 The energy coupling between the middle fiber core and the right core of the present invention;

[0035] Figure 5 The OAM phase distribution of the right core of the present invention;

[0036] Figure 6 The energy coupling between the middle fiber core and the left core of the present invention;

[0037] Figure 7 The OAM phase distribution of the left core of the present invention;

[0038] Figure 8 Schematic cross-sectional view of Example 1 of the present invention;

[0039] Figure 9 Schematic cross-sectional view of Example 2 of the present invention;

[0040] Figure 10 Schematic cross-sectional view of Example 3 of the present invention;

[0041] Figure 11 Schematic cross-sectional view of Example 4 of the present invention;

[0042] Description of reference numerals:

[0043] 1. Laser light source; 2. Single-mode optical fiber; 3. Multi-core twisted optical fiber. DETAILED DESCRIPTION

[0044] To make the above-mentioned objectives, features, and advantages of the present invention more clearly understood, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be noted that the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort are also within the scope of protection of the present invention.

[0045] like Figure 1 As shown in FIG. 1 , the chiral multidimensional, multiband controllable OAM beam generator of the present invention includes a laser source 1 and a multi-core twisted fiber 3. Light from the laser source 1 enters the multi-core twisted fiber 3. The central core of the multi-core twisted fiber 3 couples with the adjacent cores, enabling the central core to selectively couple with a specific "satellite core" over a wide wavelength range, thereby exciting the satellite core's higher-order modes.

[0046] like Figure 2 As shown in FIG, the chiral multi-dimensional multi-band controllable OAM beam generator of the present invention comprises a laser light source 1, a single-mode optical fiber 2 and a multi-core twisted optical fiber 3. The light of the laser light source 1 is transmitted through the single-mode optical fiber 2, and the single-mode optical fiber 2 and the multi-core twisted optical fiber 3 are fused. Figure 3 As shown, the core of the multi-core twisted fiber 3 has a certain twist rate. The core of the single-mode fiber 2 is coaxial with the core of the multi-core twisted fiber 3. At this time, light enters the multi-core twisted fiber 3 through the single-mode fiber 2. Because the middle core of the multi-core twisted fiber 3 and the adjacent cores are coupled, the middle core can selectively couple with a specific "satellite core" within a wide wavelength range to excite the high-order mode of the "satellite core". Figure 8 As shown in the figure, due to the different distances P1 and P2 between the "satellite cores" A2 and A3 and the center of the fiber, and the different distances K1 and K2 between the edge of the "satellite core" and the edge of the middle core A1, A2 and A3 are affected differently by the twist, which in turn affects the refractive index of the two cores differently. Furthermore, the diameters of A2 and A3 are different. Therefore, under multiple influencing factors, in different wavelength bands, the fundamental mode of the middle core can selectively couple with a specific "satellite core", thereby generating a specific high-order mode of the specific "satellite core", such as Figure 4 、 Figure 6 shown.

[0047] Because the high-order mode after twisting changes from a scalar mode to a vector mode, it carries orbital angular momentum. Therefore, the orbital angular momentum modes of multiple "satellite cores" can be excited by selective coupling between the middle core of the twisted fiber and the "satellite core", thereby achieving multi-dimensional and multi-band OAM beam generation, such as Figure 5 、 Figure 7 shown.

[0048] The wavelength of the laser light source 1 may be 980 nm, 1050 nm or other commonly used wavelengths of laser light sources 1 .

[0049] The fiber type of single-mode fiber 2 is G.652.

[0050] The core diameter of the single-mode optical fiber 2 can be selected to be 9-11 μm, preferably 10 μm.

[0051] The cladding diameter of the single-mode optical fiber 2 can be selected to be 124-126 μm, preferably 125 μm.

[0052] The coating diameter of the single-mode optical fiber 2 can be selected to be 249-251 μm, preferably 250 μm.

[0053] The refractive index of the core of the single-mode optical fiber 2 can be selected to be 1.44-1.48, preferably 1.46.

[0054] The diameter of the middle core of the multi-core twisted optical fiber 3 matches the diameter of the core of the single-mode optical fiber 2 to facilitate optical fiber fusion splicing.

[0055] The diameter of the cladding of the multi-core twisted optical fiber 3 matches the diameter of the cladding of the single-mode optical fiber 2 to facilitate the fusion splicing of the optical fibers.

[0056] The multi-core twisted optical fiber 3 may be three-core, four-core or five-core, preferably three-core. The "guard core" of the multi-core twisted optical fiber 3 may be a plurality of large-sized fiber cores, with a diameter of 12-15 μm.

[0057] The refractive index of the middle core of the multi-core twisted optical fiber 3 can be selected to be 1.44-1.48, preferably 1.46.

[0058] The refractive index of the “guard core” of the multi-core twisted optical fiber 3 is smaller than that of the central core, and can be selected from 1.42 to 1.46, preferably 1.44.

[0059] The distance between the "satellite cores" should be greater than the distance from the middle core to the "satellite core". The distance between the "satellite cores" and the middle core of the multi-core twisted optical fiber 3 can be selected to be 13-18 μm.

[0060] The twist rate of the multi-core twisted optical fiber 3 can be selected from 2000 rad / m to 2300 rad / m, preferably 2100 rad / m.

[0061] The twist length of the multi-core twisted optical fiber 3 can be selected to be 2800 μm-3000 μm, preferably 2900 μm.

[0062] The method for preparing the chiral multi-dimensional multi-band controllable OAM beam generator comprises:

[0063] S1. Arrange the fiber cores by stacking method, and then prepare multi-core optical fiber by drawing;

[0064] S2. heating the prepared multi-core optical fiber to make it soft, applying a twisting force to the multi-core optical fiber to twist it, thereby obtaining a twisted multi-core optical fiber;

[0065] S3. Use a fiber fusion splicer to fusion-splice single-mode optical fibers, twisted multi-core optical fibers, and pigtails of laser light sources.

[0066] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, which are intended to explain rather than limit this patent.

[0067] Example 1

[0068] like Figure 8 As shown, a chiral multi-dimensional multi-band OAM beam generator is composed of a laser light source 1, a single-mode optical fiber 2 and a multi-core twisted optical fiber 3.

[0069] The multi-core twisted optical fiber 3 in this example has three cores and can be selectively coupled with a specific "satellite core" to enable flexible orbital angular momentum tuning.

[0070] The optional diameter of the "guard core" is 12-15 μm, the left core A2 is preferably 14 μm, and the right core A3 is preferably 13 μm.

[0071] The refractive index of the "guard core" of the multi-core twisted optical fiber 3 is smaller than that of the middle core. The refractive index of the left core A2 and the right core A3 can be selected from 1.42 to 1.46, with the left core A2 preferably being 1.445 and the right core A3 preferably being 1.44.

[0072] The distance between the "satellite cores" should be greater than the distance from the middle core to the "satellite core." The distance between the "satellite cores" and the middle core of the multi-core twisted optical fiber 3 can be selected to be 13-18 μm. The distance P2 of the left core A2 is preferably 16 μm, and the distance P1 of the right core A3 is preferably 14 μm.

[0073] The wavelength of the laser light source 1 may be 980 nm, 1050 nm or other commonly used wavelengths of laser light sources 1 .

[0074] The fiber type of single-mode fiber 2 is G.652.

[0075] The core diameter of the single-mode optical fiber 2 can be selected to be 9-11 μm, preferably 10 μm.

[0076] The cladding diameter of the single-mode optical fiber 2 can be selected to be 124-126 μm, preferably 125 μm.

[0077] The coating diameter of the single-mode optical fiber 2 can be selected to be 249-251 μm, preferably 250 μm.

[0078] The refractive index of the core of the single-mode optical fiber 2 can be selected to be 1.44-1.48, preferably 1.46.

[0079] The diameter of the middle core of the multi-core twisted optical fiber 3 matches the diameter of the core of the single-mode optical fiber 2 to facilitate optical fiber fusion splicing.

[0080] The diameter of the cladding of the multi-core twisted optical fiber 3 matches the diameter of the cladding of the single-mode optical fiber 2 to facilitate the fusion splicing of the optical fibers.

[0081] The refractive index of the middle core of the multi-core twisted optical fiber 3 can be selected to be 1.44-1.48, preferably 1.46.

[0082] The twist rate of the multi-core twisted optical fiber 3 can be selected from 2000 rad / m to 2300 rad / m, preferably 2100 rad / m.

[0083] The twist length of the multi-core twisted optical fiber 3 can be selected to be 2800 μm-3000 μm, preferably 2900 μm.

[0084] Example 2

[0085] like Figure 9 As shown, a chiral multi-dimensional multi-band OAM beam generator is composed of a laser light source 1, a single-mode optical fiber 2 and a multi-core twisted optical fiber 3.

[0086] The multi-core twisted optical fiber 3 in this example has four cores, which can controllably generate multi-dimensional and multi-band OAM beams with more channels and orders.

[0087] The optional diameters of the three “satellite cores” are 12-15 μm, wherein the diameter of A2 is preferably 15 μm, and the diameters of A3 and A4 are preferably 12 μm.

[0088] The refractive index of the "satellite core" is lower than that of the central fiber core. The refractive index of the three "satellite cores" A2, A3, and A4 is preferably 1.43, 1.44, and 1.45.

[0089] The distance between the satellite cores should be greater than the distance from the intermediate core to the satellite core. The distance between the satellite core and the intermediate core of multi-core twisted optical fiber 3 can be selected to be 13-18 μm. The distance P1 from the center of A2 and A3 to the center of the optical fiber is preferably 14 μm, and the distance P2 from the center of A4 to the center of the optical fiber is preferably 16 μm.

[0090] The wavelength of the laser light source 1 may be 980 nm, 1050 nm or other commonly used wavelengths of laser light sources 1 .

[0091] The fiber type of single-mode fiber 2 is G.652.

[0092] The core diameter of the single-mode optical fiber 2 can be selected to be 9-11 μm, preferably 10 μm.

[0093] The cladding diameter of the single-mode optical fiber 2 can be selected to be 124-126 μm, preferably 125 μm.

[0094] The coating diameter of the single-mode optical fiber 2 can be selected to be 249-251 μm, preferably 250 μm.

[0095] The refractive index of the core of the single-mode optical fiber 2 can be selected to be 1.44-1.48, preferably 1.46.

[0096] The diameter of the middle core of the multi-core twisted optical fiber 3 matches the diameter of the core of the single-mode optical fiber 2 to facilitate optical fiber fusion splicing.

[0097] The diameter of the cladding of the multi-core twisted optical fiber 3 matches the diameter of the cladding of the single-mode optical fiber 2 to facilitate the fusion splicing of the optical fibers.

[0098] The refractive index of the middle core of the multi-core twisted optical fiber 3 can be selected to be 1.44-1.48, preferably 1.46.

[0099] The twist rate of the multi-core twisted optical fiber 3 can be selected from 2000 rad / m to 2300 rad / m, preferably 2100 rad / m.

[0100] The twist length of the multi-core twisted optical fiber 3 can be selected to be 2800 μm-3000 μm, preferably 2900 μm.

[0101] Example 3

[0102] like Figure 10 As shown, a chiral multi-dimensional multi-band OAM beam generator is composed of a laser light source 1, a single-mode optical fiber 2 and a multi-core twisted optical fiber 3.

[0103] The difference between this embodiment and the previous one is that a cladding layer is added to the periphery of the "satellite core" A2, whose refractive index is lower than that of A2 but higher than that of the cladding of the entire optical fiber, further realizing the function of realizing multi-channel high-order modes at specific locations.

[0104] The optional diameters of the three satellite cores are 12-15 μm, of which the diameter of A2 is preferably 15 μm, the diameters of A3 and A4 are preferably 12 μm, and the diameter of the A2 cladding is preferably 17 μm.

[0105] The refractive index of the satellite core is lower than that of the central core. The refractive indices of the three satellite cores A2, A3, and A4 are preferably 1.43, 1.44, and 1.45, respectively. The refractive index of the A2 cladding is preferably 1.425.

[0106] The distance between the satellite cores should be greater than the distance between the intermediate core and the satellite core. The distance between the satellite core and the intermediate core of multi-core twisted fiber 3 can be selected to be 13-18 μm. Specifically, the distance P1 from the center of A2 and A3 to the fiber center is 14 μm, and the distance P2 from the center of A4 to the fiber center is 16 μm.

[0107] The wavelength of the laser light source 1 may be 980 nm, 1050 nm or other commonly used wavelengths of laser light sources 1 .

[0108] The fiber type of single-mode fiber 2 is G.652.

[0109] The core diameter of the single-mode optical fiber 2 can be selected to be 9-11 μm, preferably 10 μm.

[0110] The cladding diameter of the single-mode optical fiber 2 can be selected to be 124-126 μm, preferably 125 μm.

[0111] The coating diameter of the single-mode optical fiber 2 can be selected to be 249-251 μm, preferably 250 μm.

[0112] The refractive index of the core of the single-mode optical fiber 2 can be selected to be 1.44-1.48, preferably 1.46.

[0113] The diameter of the middle core of the multi-core twisted optical fiber 3 matches the diameter of the core of the single-mode optical fiber 2 to facilitate optical fiber fusion splicing.

[0114] The diameter of the cladding of the multi-core twisted optical fiber 3 matches the diameter of the cladding of the single-mode optical fiber 2 to facilitate the fusion splicing of the optical fibers.

[0115] The refractive index of the middle core of the multi-core twisted optical fiber 3 can be selected to be 1.44-1.48, preferably 1.46.

[0116] The twist rate of the multi-core twisted optical fiber 3 can be selected from 2000 rad / m to 2300 rad / m, preferably 2100 rad / m.

[0117] The twist length of the multi-core twisted optical fiber 3 can be selected to be 2800 μm-3000 μm, preferably 2900 μm.

[0118] Example 4

[0119] like Figure 11 As shown, a chiral multi-dimensional multi-band OAM beam generator is composed of a laser light source 1, a single-mode optical fiber 2 and a multi-core twisted optical fiber 3.

[0120] The difference between this embodiment and the previous one is that a cladding layer is added to the periphery of each "satellite core" with a refractive index lower than that of the respective "satellite core" but higher than the cladding of the entire optical fiber. This further enables the function of realizing multi-channel high-order modes at specific locations.

[0121] The optional diameters of the three satellite cores are 12-15 μm, of which the diameter of A2 is preferably 15 μm, the diameters of A3 and A4 are preferably 12 μm, and the diameter of the A2 cladding is preferably 17 μm.

[0122] The refractive index of the satellite core is lower than that of the central fiber core. The refractive indices of the three satellite cores, A2, A3, and A4, are preferably 1.43, 1.44, and 1.45, respectively. The refractive index of the A2 cladding is preferably 1.425, the refractive index of the A3 cladding is preferably 1.435, and the refractive index of the A4 cladding is preferably 1.445.

[0123] The distance between the satellite cores should be greater than the distance between the intermediate core and the satellite core. The distance between the satellite core and the intermediate core of multi-core twisted fiber 3 can be selected to be 13-18 μm. Specifically, the distance P1 from the center of A2 and A3 to the fiber center is 14 μm, and the distance P2 from the center of A4 to the fiber center is 16 μm.

[0124] The wavelength of the laser light source 1 may be 980 nm, 1050 nm or other commonly used wavelengths of laser light sources 1 .

[0125] The fiber type of single-mode fiber 2 is G.652.

[0126] The core diameter of the single-mode optical fiber 2 can be selected to be 9-11 μm, preferably 10 μm.

[0127] The cladding diameter of the single-mode optical fiber 2 can be selected to be 124-126 μm, preferably 125 μm.

[0128] The coating diameter of the single-mode optical fiber 2 can be selected to be 249-251 μm, preferably 250 μm.

[0129] The refractive index of the core of the single-mode optical fiber 2 can be selected to be 1.44-1.48, preferably 1.46.

[0130] The diameter of the middle core of the multi-core twisted optical fiber 3 matches the diameter of the core of the single-mode optical fiber 2 to facilitate optical fiber fusion splicing.

[0131] The diameter of the cladding of the multi-core twisted optical fiber 3 matches the diameter of the cladding of the single-mode optical fiber 2 to facilitate the fusion splicing of the optical fibers.

[0132] The refractive index of the middle core of the multi-core twisted optical fiber 3 can be selected to be 1.44-1.48, preferably 1.46.

[0133] The twist rate of the multi-core twisted optical fiber 3 can be selected from 2000 rad / m to 2300 rad / m, preferably 2100 rad / m.

[0134] The twist length of the multi-core twisted optical fiber 3 can be selected to be 2800 μm-3000 μm, preferably 2900 μm.

[0135] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A chiral multi-dimensional multi-band controllable OAM beam generator, characterized in that: Including laser light source and multi-core twisted optical fiber; The chiral multi-dimensional multi-band controllable OAM beam generator further comprises a single-mode optical fiber, and the light of the laser light source enters the multi-core twisted optical fiber through the single-mode optical fiber; The core of the single-mode fiber is coaxial with the core of the multi-core twisted fiber; The diameter of the middle core of the multi-core twisted optical fiber matches the diameter of the core of the single-mode optical fiber to facilitate optical fiber fusion splicing; The diameter of the multi-core twisted optical fiber cladding matches the diameter of the single-mode optical fiber cladding to facilitate optical fiber fusion splicing; A cladding is added to the periphery of at least one satellite core in the multi-core twisted optical fiber, and the refractive index of the cladding is lower than that of the respective satellite core but higher than that of the cladding of the entire optical fiber; The multi-core twisted optical fiber has a core diameter of 12-15 μm; The refractive index of the middle core of the multi-core twisted optical fiber is 1.44-1.48; the refractive index of the guard core of the multi-core twisted optical fiber is smaller than that of the middle core, and the refractive index of the guard core of the multi-core twisted optical fiber is 1.42-1.46; The distance between the satellite cores of the multi-core twisted optical fiber is greater than the distance from the intermediate core to the satellite core, and the distance between the satellite core and the intermediate core of the multi-core twisted optical fiber is 13-18 μm; The twist rate of the multi-core twisted optical fiber is 2000rad / m-2300rad / m; the twist length of the multi-core twisted optical fiber is 2800μm-3000μm; The core diameter of the single-mode optical fiber is 9-11 μm; the cladding diameter of the single-mode optical fiber is 124-126 μm; the coating diameter of the single-mode optical fiber is 249-251 μm; and the refractive index of the core of the single-mode optical fiber is 1.44-1.

48.

2. The chiral multi-dimensional multi-band controllable OAM beam generator according to claim 1, characterized in that: The multi-core twisted optical fiber has three cores, four cores or five cores.

3. A method for preparing a chiral multi-dimensional multi-band controllable OAM beam generator according to claim 1 or 2, characterized in that: include: S1. Arrange the fiber cores by stacking method, and then prepare multi-core optical fiber by drawing; S2. heating the prepared multi-core optical fiber to make it soft, applying a twisting force to the multi-core optical fiber to twist it, thereby obtaining a twisted multi-core optical fiber; S3. Use a fiber fusion splicer to fusion-splice single-mode optical fibers, twisted multi-core optical fibers, and pigtails of laser light sources.

Images