A structurally composite ultra-wideband high-gain vortex optical fiber and a preparation method thereof

Abstract

The present invention discloses a structurally composite ultra-wideband high-gain vortex optical fiber and a preparation method thereof. The optical fiber includes a passive core, an active inner ring core, an active outer ring core and a cladding from the inside to the outside. The passive core is an optical material or pore that is not doped with activated ions; the active inner ring core and the outer ring core are laser materials doped with different rare earth luminescent ions, and different luminescent bands correspond to different rare earth luminescent ion combinations, such as Tb-Tm for the blue light band, Eu-Sm for the red light band, Nd-Yb for the 1 μm band, Er-Tm for the 1.5 μm band, Tm-Ho for the 2 μm band, and Er-Ho or Er-Dy for the 3 μm band. The structurally composite vortex optical fiber of the present invention partitions the rare earth luminescent ions, which can effectively avoid unnecessary energy transfer processes, improve the optical fiber luminescence efficiency, increase the optical fiber luminescence bandwidth, and is applied to high-performance vortex fiber lasers and broadband orbital angular momentum multiplexing systems.

Description

Technical Field

[0001] The invention belongs to the technical field of special laser optical fibers, and in particular relates to a structurally composite ultra-wideband high-gain vortex optical fiber and a preparation method thereof. Background Art

[0002] Optical fiber is an important medium for information transmission in today's society. In recent years, with the rapid development of industries such as artificial intelligence, cloud computing, and the Internet of Things, data traffic has shown a blowout growth, which has put forward higher requirements for communication capacity.

[0003] Broadband active optical fiber can effectively broaden the signal transmission band and is a feasible solution to the current insufficient communication capacity. Traditional broadband active optical fiber is generally achieved in the following ways: First, it is co-doped with multiple rare earth ions, such as Nd / Yb ion co-doped optical fiber in the 1 μm band (referenced in Broadband 1.0 µm emission in Nd 3+ / Yb 3+ co-dopedphosphate glasses and fibers for photonic applications》), Er / Tm ion co-doped optical fiber in the 1.5 μm band (literature "Broadband emission in Er 3+ -Tm 3+ codoped tellurite fibre”), 2 μm band Tm / Ho ion co-doped broadband optical fiber (literature “Broadband high-gain Tm 3+ / Ho 3+ co-dopedgermanate glass multimaterial fiber for fiber lasers above 2 µm》); the second is through doping with transition metal ions or heavy metal ions, such as Bi ion doping broadband active fiber (CN105467512A). However, for the co-doping of multiple rare earth ions, when the rare earth ion doping concentration reaches a certain level, the distance between different rare earth ions is less than the critical distance, and unnecessary energy transfer processes will occur, which makes the rare earth doping concentration of co-doped broadband optical fiber usually low and the gain coefficient low. For transition metal ion or heavy metal ion doped optical fiber, since its ion valence state is difficult to control, for example, Bi ions usually coexist with +1, +2, and +5 valences, the stability of the optical fiber is ultimately poor. How to make multiple rare earth ions emit light efficiently in one optical fiber without affecting each other, so as to achieve mutual compensation of the gain bands of multiple rare earths is an urgent problem to be solved in the realization of broadband high-gain optical fiber.

[0004] Furthermore, based on traditional optical communication system transmission technologies, such as time division multiplexing, wavelength division multiplexing and digital coherence technology, the single wavelength transmission rate has reached 100 Tbit / s, which is close to the theoretical Shannon limit. In order to further expand the communication capacity, the space division multiplexing technology of optical fiber communication has become a research hotspot. Space division multiplexing technology mainly includes core division multiplexing and mode division multiplexing, and orbital angular momentum multiplexing technology is an important part of mode division multiplexing technology. Orbital angular momentum (OAM) beam refers to a beam carrying orbital angular momentum, also known as a vortex beam. The significant property of the orbital angular momentum beam is its spiral phase. The OAM mode in the optical fiber is formed by the linear superposition of the odd and even modes of four vector eigenmodes of the same order. At present, the research on vortex fiber is mainly focused on the generation and stable transmission of vortex light; for example, patent application number CN109100827A proposes an optical fiber for vortex light beam transmission and maintenance, and patent application number CN116444142A invents a vortex gain fiber and its preparation method. There is a lack of research on the expansion of the gain range of vortex fiber, so it is of theoretical and practical significance to design a specific vortex fiber structure and expand the gain range of vortex fiber from the perspective of fiber structure.

[0005] In summary, designing and preparing a structural composite optical fiber with ultra-wideband high gain characteristics and stable transmission of OAM modes has a relatively ideal application prospect and is a feasible way to further increase communication capacity. Summary of the invention

[0006] In order to solve the problem of narrow gain bandwidth of existing vortex gain optical fibers, the present invention provides a structurally composite ultra-wideband high-gain vortex optical fiber and a preparation method thereof.

[0007] The purpose of the present invention is achieved by at least one of the following technical solutions.

[0008] A structurally composite ultra-wideband high-gain vortex optical fiber comprises a passive fiber core, an active inner ring core, an active outer ring core and a cladding which are sequentially wrapped from the inside to the outside;

[0009] The active inner ring core and the active outer ring core are both laser materials doped with one or more rare earth luminescent ions, and at least one of the rare earth luminescent ions doped in the active inner ring core and the active outer ring core is different.

[0010] Furthermore, part of the materials on the active inner ring core and the active outer ring core can replace each other; preferably, half of the areas of the inner ring and outer ring corresponding to the active inner ring core and the active outer ring core are replaced with each other, and the corresponding materials where the inner and outer rings contact each other are different.

[0011] Furthermore, the laser material includes glass, crystal, ceramic or plastic material; the rare earth luminescent ions include Tm, Ho, Er, Nd, Yb, Sm or Eu; and the rare earth luminescent ion doping concentration in the laser material is ≥1 mol%.

[0012] Furthermore, the luminous wavelength band of the ultra-wideband high-gain vortex optical fiber is determined by the active inner ring core and the active outer ring core, and the luminous wavelength band of the active inner ring core and the active outer ring core is the luminous wavelength band of the optical fiber;

[0013] Different luminous bands of active inner ring cores or active outer ring cores correspond to different rare earth luminescent ion combinations, as follows:

[0014] The blue light band is Tb-Tm, the red light band is Eu-Sm, the 1 μm band is Nd-Yb, the 1.5 μm band is Er-Tm, the 2 μm band is Tm-Ho, and the 3 μm band is Er-Ho or Er-Dy;

[0015] The transmittance of the laser material doped with one or more rare earth luminescent ions in the luminescent band of the corresponding doped rare earth ions is ≥80%.

[0016] Furthermore, for the same laser material, the rare earth luminescent ions therein are uniformly doped;

[0017] When different rare earth luminescent ions are doped in the active inner ring core or the active outer ring core, a sensitizer is added to simplify the pumping method. For example, for the Er-Ho combination method in the 3 μm band, Yb ions can be added as a sensitizer to simplify the pumping method.

[0018] Furthermore, the materials of the passive core and cladding include undoped glass, crystal, ceramic or plastic materials.

[0019] Furthermore, the passive fiber core is replaced by a hollow hole formed by wrapping the active inner ring core (air fiber core).

[0020] Furthermore, the structure of the cladding layer includes a uniform step structure, a photonic crystal structure or a Bragg structure.

[0021] Furthermore, the refractive index of the material of the active inner ring core and the active outer ring core, compared with the refractive index of the material of the passive fiber core and the cladding, differs by more than 2%.

[0022] The present invention provides a method for preparing a structurally composite ultra-wideband high-gain vortex optical fiber, comprising the following steps:

[0023] S1. Preparation of active and passive matrix materials: preparing matrix materials of passive fiber core, active inner ring core, active outer ring core and cladding respectively by high temperature melting method or CVD method;

[0024] S2. Processing of optical fiber preform: processing the matrix material prepared in step S1 into a set geometric size and polishing it to optical precision to obtain a passive fiber core rod, an active inner ring core tube, an active outer ring core tube and a cladding tube respectively;

[0025] S3, primary drawing: assembling and drawing the passive fiber core rod, the active inner ring core tube and the active outer ring core tube from the inside to the outside to obtain a composite fiber core rod with an annular structure;

[0026] S4, secondary drawing: The obtained composite fiber core rod and cladding tube are nested and combined for drawing, and the fiber diameter is controlled by controlling the drawing speed and feeding speed, and finally a structurally composite broadband high-gain vortex fiber is obtained.

[0027] Furthermore, in step S2, the optical fiber preform preparation method includes a tube-rod method, a chemical vapor deposition method, 3D printing, a pressure-assisted melt filling method, an extrusion method or a suction method.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] (1) The composite broadband high-gain vortex optical fiber provided by the present invention can make different rare earth luminescent ions emit light efficiently in the same optical fiber through rare earth regional doping, thus avoiding unnecessary energy transfer process and improving optical fiber efficiency.

[0030] (2) The structurally composite broadband high-gain vortex optical fiber provided by the present invention has the characteristics of large gain bandwidth, high gain coefficient per unit length, and high OAM mode capacity, and can be applied to optical fiber amplifiers to increase communication capacity.

[0031] (3) The present invention can be applied to vortex fiber amplifiers to effectively broaden the gain bandwidth and improve the unit distance gain coefficient; it can also be applied to vortex optical fiber lasers to output vortex laser signals. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A schematic diagram of the structure of a vortex optical fiber is provided for Example 1 of the present invention;

[0033] Figure 2 Providing OAM of vortex optical fiber for embodiment 1 of the present invention 1,1 Normalized electric field intensity distribution diagram of the mode;

[0034] Figure 3 A schematic diagram of ASE spectrum of vortex optical fiber is provided for Example 1 of the present invention;

[0035] Figure 4 A schematic diagram of the structure of a vortex optical fiber is provided for Example 3 of the present invention;

[0036] Figure 5TM for providing vortex optical fiber for embodiment 4 of the present invention 0，1 Schematic diagram of the normalized mode field distribution. DETAILED DESCRIPTION

[0037] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments and drawings, but the present invention is not limited to the embodiments.

[0038] Embodiment 1:

[0039] A 2 μm band structured ultra-wideband high-gain vortex fiber, such as Figure 1 As shown, it includes a passive core 101, an active inner ring core 102, an active outer ring core 103 and a cladding 104 which are sequentially wrapped from the inside to the outside. The passive core 101 is a germanate passive core, the active inner ring core 102 is a Tm-doped active inner ring core, and the active outer ring core 103 is a Tm / Ho co-doped active outer ring core.

[0040] In this embodiment, the passive core, Tm-doped active inner ring core, Tm / Ho co-doped active outer ring core and cladding are all made of germanate glass materials. The components of the germanate passive core and cladding glass are (7-15)BaO-(7-15)Ga2O3-(65-85)GeO2-(1-5)La2O3. The components of the Tm-doped active inner ring core glass are (7-15)BaO-(7-15)Ga2O3-(62-69)GeO2-(1-5)La2O3-1Tm2O3. The components of the Tm / Ho co-doped active outer ring core glass are (7-15)BaO-(7-15)Ga2O3-(61-68)GeO2-(1-5)La2O3-1Tm2O3-1Ho2O3.

[0041] In this embodiment, by adjusting the composition ratio of the passive core, the Tm-doped active inner ring core, the Tm / Ho co-doped active outer ring core and the cladding glass, the refractive indexes are 1.6937, 1.7376, 1.7376 and 1.6937 respectively, and the refractive index difference between the active region and the passive region of the optical fiber is 2.1%.

[0042] In this embodiment, Figure 1 As shown, the geometric parameters of the vortex optical fiber described in this embodiment are r1=4 μm, r2=8 μm, r3=14 μm, and r4=62.5 μm.

[0043] In this embodiment, a broadband high-gain vortex optical fiber with a 2 μm band structure composite is prepared by a rod-tube method, and the specific steps are as follows:

[0044] The first step is to prepare active and passive glass: passive fiber core glass, active inner ring core glass, active outer ring core glass and cladding glass are prepared separately by high-temperature melting method; the specific process is to weigh the raw materials according to the formula and mix them thoroughly, and then melt the raw materials in a high-temperature furnace at 1300~1400 ℃ (which may fluctuate according to the quality of the raw materials) to obtain molten glass, and then cast the molten glass into shape, quickly cool down (cooling rate is greater than 10℃ / min) and precisely anneal (keep warm at 600~670℃ for 20 hours, and cool to room temperature at a rate of 5℃ / h) to obtain active and passive glass of suitable size.

[0045] The second is the processing of optical fiber preform rods: the prepared glass is processed into the designed geometric dimensions and polished to optical precision to obtain passive fiber core glass rods, active inner ring core glass tubes, active outer ring core glass tubes and cladding glass tubes respectively.

[0046] Then comes the primary drawing: assemble the passive fiber core glass rod, the active inner ring core glass tube and the active outer ring core glass tube, and draw them at 780~830℃ (which can fluctuate according to the size of the glass) to obtain a composite fiber core rod with an annular structure.

[0047] The final step is secondary drawing: the obtained composite fiber core rod is combined with the cladding glass tube for drawing at 800~850 ℃, and the fiber diameter is controlled by controlling the drawing speed and feeding speed, and finally a structurally composite broadband high-gain vortex fiber is obtained.

[0048] In this embodiment, Figure 2 The OAM of the broadband high-gain vortex fiber with the 2 μm band structure is 1,1 Normalized electric field intensity distribution diagram of the mode, arrows indicate direction, and arrow size indicates strength. It can be seen that the mode is well confined in the composite fiber core, which is due to the large refractive index difference between the glass materials in the active and passive regions of the vortex fiber.

[0049] In this embodiment, the ASE (amplified stimulated emission) spectrum test results of the 2 μm band structure composite broadband high gain vortex fiber are as follows: Figure 3 , ranging from 1700 to 2150 nm, and a gain bandwidth greater than 300 nm, which is greater than the 250 nm bandwidth of conventional unstructured composite Tm / Ho co-doped fibers (referenced in the literature on Broadband high-gain Tm 3+ / Ho 3+The invention discloses a co-doped germanateglass multimaterial fiber for fiber lasers above 2 μm. The unit distance gain coefficient is greater than 1 dB / cm. The broadband high-gain vortex fiber with 2 μm band structure composite is a good laser medium for ultra-broadband vortex fiber lasers.

[0050] Embodiment 2:

[0051] A 1.5 μm band structurally composite broadband high-gain vortex optical fiber comprises a passive fiber core, a Tm-doped active inner ring core, an Er-doped active outer ring core and a cladding.

[0052] In this embodiment, the passive core, Tm-doped active inner ring core, Er-doped active outer ring core and cladding are all made of germanate glass material. The composition of the germanate passive core and cladding glass is (7-15)BaO-(7-15)Ga2O3-(65-85)GeO2-(1-5)La2O3. The composition of the Tm-doped active inner ring core glass is (7-15)BaO-(7-15)Ga2O3-(62-69)GeO2-(1-5)La2O3-1Tm2O3. The composition of the Er-doped active outer ring core glass is (7-15)BaO-(7-15)Ga2O3-(62-69)GeO2-(1-5)La2O3-1Er2O3.

[0053] In this embodiment, by adjusting the composition ratio of the passive core, the Tm-doped active inner ring core, the Er-doped active outer ring core and the cladding glass, the refractive index is 1.6725, 1.7376, 1.7381 and 1.6725, respectively, and the refractive index difference between the active region and the passive region of the optical fiber is 2.1%. The preparation steps of the 1.5 μm band vortex optical fiber described in this embodiment are the same as those in Example 1.

[0054] In this embodiment, the geometric parameters of the vortex fiber described in this embodiment are r1=3 μm, r2=7 μm, r3=9 μm, and r4=62.5 μm. The broadband high-gain vortex fiber with a 1.5 μm band structure composite described in this embodiment can effectively broaden the gain range of Er fiber in the L and U bands, and is a good laser gain material for communication band vortex fiber lasers or amplifiers.

[0055] Embodiment 3:

[0056] A 1 μm band structured broadband high-gain vortex fiber, such as Figure 4 As shown, it includes a phosphate-free passive core 301 , a Nd-doped active inner ring core 302 , a Nd / Yb co-doped active outer ring core 303 and a cladding glass 104 .

[0057] In this embodiment, the passive core, Nd-doped active inner ring core, Nd / Yb co-doped active outer ring core and cladding are all made of phosphate glass materials. The composition of the phosphate passive core and cladding glass is (60-88)P2O5-(5-15)BaO-(5-15)Al2O3-(1-5)La2O3-(1-5)K2O. The composition of the Nd-doped active inner ring core glass is (58-86)P2O5-(5-15)BaO-(5-15)Al2O3-(1-5)La2O3-(1-5)K2O3-2Nd2O3. The composition of Nd / Yb co-doped active outer ring core glass is (57-85)P2O5-(5-15)BaO-(5-15)Al2O3-(1-5)La2O3-(1-5)K2O3-2Nd2O3-1Yb2O3.

[0058] In this embodiment, by adjusting the composition ratio of the passive core, Nd-doped active inner ring core, Nd / Yb co-doped active outer ring core and cladding glass, the refractive indexes are 1.5193, 1.5927, 1.5924 and 1.5193 respectively, and the refractive index difference between the active region and the passive region of the optical fiber is 2.6%.

[0059] In this embodiment, the active annular region of the vortex optical fiber is more complex, and the corresponding inner ring and outer ring have half of the area replaced with each other, and the corresponding materials where the inner and outer rings contact each other are different; the optical fiber is still prepared by the rod-tube method, and the specific steps are as follows:

[0060] (1) Preparation of active and passive glass: Passive core glass, active inner ring core glass, active outer ring core glass and cladding glass are prepared by high-temperature melting method. The specific process is to weigh the raw materials according to the formula and mix them thoroughly. Then, the raw materials are melted in a high-temperature furnace at 1000-1250 °C (which may fluctuate according to the quality of the raw materials) to obtain glass liquid. The glass liquid is then cast into shape, cooled rapidly (cooling rate greater than 10 °C / min) and precisely annealed (maintained at 600-670 °C for 20 hours and cooled to room temperature at a rate of 5 °C / h) to obtain active and passive glass of suitable size.

[0061] (2) Preparation of bulk active composite glass: First, grind and polish the outer surfaces of Nd-doped glass and Nd / Yb co-doped glass. Then, fit the polished surfaces of the two glasses tightly together and place them in a high-temperature furnace for hot melting at 550-620 °C for 10 minutes. Then, cool them rapidly (cooling rate greater than 10 °C / min) to 500-520 °C and perform precision annealing (keep at 500-520 °C for 30 hours and cool to room temperature at a rate of 3 °C / h). Finally, Nd-doped and Nd / Yb co-doped zoned composite laser glasses are obtained.

[0062] (3) Processing of optical fiber preform rods: The prepared passive glass and active composite glass are processed into the designed geometric dimensions and polished to optical precision to obtain the passive fiber core glass rod, active composite inner ring core glass tube, active composite outer ring core glass tube and cladding glass tube respectively.

[0063] (4) Drawing: In the first drawing process, the passive core glass rod, the active inner ring core glass tube and the active outer ring core glass tube are assembled and drawn at 560-600 °C to obtain a composite core rod with a ring structure. In the second drawing process, the obtained composite core rod is combined with the cladding glass tube and drawn at 580-650 °C. The fiber diameter is controlled by controlling the drawing speed and the feeding speed, and finally a structurally composite broadband high-gain vortex fiber is obtained.

[0064] The geometric parameters of the vortex fiber in this embodiment are r1=2 μm, r2=5 μm, r3=8.5 μm, and r4=62.5 μm. Table 1 shows the vector mode effective refractive index of the vortex fiber.

[0065] Table 1

[0066]

[0067] The 1 μm band structure composite broadband high-gain vortex fiber described in this embodiment combines Nd 3+ Ions and Yb 3 + The emission wavelength range of the ions can be applied to laser systems such as vortex fiber lasers in the range of 950 to 1150 nm.

[0068] Embodiment 4:

[0069] A broadband high-gain vortex optical fiber with a composite red light band structure comprises an air core, an Eu-doped active inner ring core, an Sm-doped active outer ring core and a cladding.

[0070] In this embodiment, the air core is a hollow area, and the Eu-doped active inner ring core, the Sm-doped active outer ring core and the cladding are all made of fluoride glass materials. The composition of the fluoride cladding glass is (55-67)ZrF4-(15-20)BaF2-(3-5)AlF3-(15-20)NaF. The composition of the Eu-doped active inner ring core glass is (46-61)ZrF4-(15-20)BaF2-(5-8)LaF3-(3-5)AlF3-(15-20)NaF-1EuF3. The composition of the Sm-doped active outer ring core glass is (46-61)ZrF4-(15-20)BaF2-(5-8)LaF3-(3-5)AlF3-(15-20)NaF-1SmF3.

[0071] In this embodiment, by adjusting the composition ratio of the Eu-doped active inner ring core, the Sm-doped active outer ring core and the cladding glass, the refractive index is 1.3854, 1.3854 and 1.4977 respectively, and the refractive index difference between the active region and the passive region of the optical fiber is 7.5%. The preparation steps of the red light band hollow vortex optical fiber described in this embodiment are the same as those in Example 1.

[0072] In this embodiment, the geometric parameters of the vortex optical fiber described in this embodiment are r1=2 μm, r2=5 μm, r3=8 μm, and r4=62.5 μm. Figure 5 The TM of the optical fiber described in this embodiment is given 0,1 Schematic diagram of normalized mode field distribution. The broadband high-gain vortex fiber with a composite red light band structure described in this embodiment realizes stable transmission of vortex light by increasing the large refractive index difference between the active region and the passive region, and is expected to be applied to vortex fiber lasers in the visible light band.

[0073] The above-described embodiments only express several implementation methods of the present invention, but should not be understood as limiting the scope of protection of the present invention. It should be pointed out that for those skilled in the art to which the present invention belongs, the supplement or optimization made to the present invention without departing from the concept of the present invention still falls within the scope of protection of the present invention.

Claims

1. A structurally complex ultra-wideband high-gain vortex optical fiber, characterized in that: It comprises a passive fiber core (101), an active inner ring core (102), an active outer ring core (103) and a cladding (104) which are wrapped in sequence from the inside to the outside; The active inner ring core (102) and the active outer ring core (103) are both laser materials doped with a rare earth luminescent ion, and the rare earth luminescent ions doped in the active inner ring core (102) and the active outer ring core (103) are different; the laser material comprises glass, crystal, ceramic or plastic material; the rare earth luminescent ion doping concentration in the laser material is ≥1 mol%; the rare earth luminescent ions comprise Tm, Ho, Er, Nd, Yb, Sm or Eu; the laser material doped with a rare earth luminescent ion has a transmittance of ≥80% in the luminescent band of the doped rare earth ion; for the same laser material, the rare earth luminescent ions therein are uniformly doped; Different luminous bands of active inner ring cores or active outer ring cores correspond to different rare earth luminescent ion combinations: The blue light band is Tb-Tm, the red light band is Eu-Sm, the 1 μm band is Nd-Yb, the 1.5 μm band is Er-Tm, the 2 μm band is Tm-Ho, and the 3 μm band is Er-Ho or Er-Dy; When different rare earth luminescent ions are doped into the active inner ring core (102) or the active outer ring core (103), a sensitizer is added to simplify the pumping mode.

2. The structure-complex ultra-wideband high-gain vortex optical fiber according to claim 1, characterized in that: The materials of the passive fiber core (101) and the cladding (104) include undoped glass, crystal, ceramic or plastic materials.

3. The structure-complex ultra-wideband high-gain vortex optical fiber according to claim 1, characterized in that: The passive fiber core (101) is replaced by a hollow hole formed by wrapping the active inner ring core (102).

4. The structure-complex ultra-wideband high-gain vortex optical fiber according to claim 1, characterized in that: The structure of the cladding (104) includes a uniform step structure, a photonic crystal structure or a Bragg structure.

5. The structure-complex ultra-wideband high-gain vortex optical fiber according to claim 1, characterized in that: The refractive index of the material of the active inner ring core (102) and the active outer ring core (103) is greater than 2% compared with the refractive index of the material of the passive fiber core (101) and the cladding (104).

6. A method for preparing a structurally composite ultra-wideband high-gain vortex optical fiber according to any one of claims 1 to 5, characterized in that: The steps include: S1. Preparation of active and passive matrix materials: preparing matrix materials of a passive fiber core (101), an active inner ring core (102), an active outer ring core (103) and a cladding (104) respectively by a high temperature melting method or a CVD method; S2. Processing of optical fiber preform: processing the matrix material prepared in step S1 into a set geometric size and polishing it to optical precision to obtain a passive fiber core rod, an active inner ring core tube, an active outer ring core tube and a cladding tube respectively; S3, primary drawing: assembling and drawing the passive fiber core rod, the active inner ring core tube and the active outer ring core tube from the inside to the outside to obtain a composite fiber core rod with an annular structure; S4, secondary drawing: The obtained composite fiber core rod and cladding tube are nested and combined for drawing, and the fiber diameter is controlled by controlling the drawing speed and feeding speed, and finally a structurally composite broadband high-gain vortex fiber is obtained.

7. The method according to claim 6, characterized in that In step S2, the optical fiber preform preparation method includes a tube-rod method, a chemical vapor deposition method, 3D printing, a pressure-assisted melt filling method, an extrusion method or a suction method.

Images