Method for actively regulating and controlling range of all-solid-state anti-resonance optical fiber transmission band

Abstract

The invention provides a method for actively regulating and controlling the range of an all-solid-state anti-resonance optical fiber transmission band, and the method comprises the following steps: placing an all-solid-state anti-resonance optical fiber in a high-temperature furnace, introducing a protective gas into the high-temperature furnace, and maintaining the flow rate of the gas to be constant; raising the temperature in the high-temperature furnace to be close to the annealing upper limit temperature of the all-solid-state anti-resonance optical fiber, and keeping the temperature for a certain time; reducing the temperature in the high-temperature furnace to room temperature, and taking out the optical fiber; and performing curing low-folding coating on the cleaned and dried surface of the optical fiber. According to the method, the target transmission band and the filtering range are obtained by determining the annealing temperature and optimizing the annealing time, the transmission band and the filtering range of the all-solid-state anti-resonance optical fiber can be actively regulated and controlled, the inherent large-mode-field single-mode transmission characteristic of the all-solid-state anti-resonance optical fiber is not influenced, and meanwhile, the transmission efficiency of the all-solid-state anti-resonance optical fiber is improved. The method has the advantages of being low in cost, uniform in element diffusion, large in adjustable range of the conveying belt and easy to operate, and has wide application prospects.

Description

Technical Field

[0001] The invention belongs to the field of high-power fiber lasers and amplifiers, and in particular relates to a method for actively regulating the range of an all-solid-state anti-resonance fiber transmission band. Background Art

[0002] All-solid-state antiresonant fibers have the characteristics of large-mode field single-mode transmission and distributed filtering, and have broad application prospects in the field of high-power fiber lasers and amplifiers. Unlike hollow-core antiresonant fibers, all-solid-state antiresonant fibers use glass cores and inner claddings. By adjusting the thickness and refractive index of the high-fold ring, the range of the resonance band and the transmission band can be controlled, and the distributed filtering effect can be achieved while ensuring large-mode field transmission of the optical fiber. In recent years, the design, preparation and laser performance of all-solid-state antiresonant fibers have received extensive attention.

[0003] However, during the high-temperature drawing process of all-solid-state antiresonant optical fiber, the interface between the high-fold ring and the inner cladding glass will be accompanied by inevitable element diffusion, which will change the refractive index distribution and thickness of the high-fold ring. According to the resonant wavelength calculation formula: It is known that this will affect the transmission band and filtering range of the all-solid-state antiresonant fiber. The diffusion process of this element is often difficult to control accurately and has a great impact on the performance of the fiber laser. Summary of the invention

[0004] In view of the above technical problems, the present invention provides a method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber. The method can actively regulate the transmission band and filtering range of the optical fiber without affecting its inherent large mode field single-mode transmission characteristics. The method is suitable for the field of high-power optical fiber lasers and amplifiers, and has the advantages of low cost, uniform element diffusion, a large adjustable transmission band range, and simple operation.

[0005] The method of actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber of the present invention comprises the following steps: S1. Place the all-solid-state anti-resonant optical fiber in a high-temperature furnace, introduce protective gas into the high-temperature furnace and maintain a constant gas flow rate. The all-solid-state anti-resonant optical fiber is composed of a core, an inner cladding and a high-refractive index ring from the inside to the outside. The core is rare earth co-doped or non-rare earth doped glass, the inner cladding is non-rare earth doped glass, the high-refractive index ring is high refractive index glass, and the refractive indices of the core, inner cladding and high-refractive index ring are n respectively. core , n clad and n t , and n t >n clad n core ; S2. Raise the temperature in the high temperature furnace to near the upper annealing temperature limit of the all-solid-state antiresonant optical fiber and maintain it for a certain period of time; S3. Lower the temperature in the high temperature furnace to room temperature and remove the optical fiber; S4. Cure the low-refractive coating on the surface of the cleaned and dried optical fiber.

[0006] Preferably, in step S1, the glass matrix of the core, the inner cladding and the high-fold ring is selected from one of quartz glass, silicate glass, phosphate glass, fluoride glass, chalcogenide glass and tellurite glass.

[0007] Preferably, in step S2 and step S3, the protective gas in step S1 is continuously introduced, and the gas flow rate is maintained equal to that in step S1. Further, the protective gas is one of oxygen, nitrogen, helium, argon, and carbon dioxide, and the gas flow rate of the protective gas is 0.2-5 L / min.

[0008] Preferably, in step S2, the upper limit temperature of annealing is when the glass viscosity drops to 10 13 The temperature at dpa·s is ±200°C near the upper limit annealing temperature.

[0009] Preferably, in step S2, the temperature in the high temperature furnace is maintained near the upper limit temperature of annealing for a certain time in the range of 0.5-48 hours. Preferably, in step S3, the time taken to reduce the temperature in the high-temperature furnace to room temperature ranges from 1 to 24 hours.

[0010] Preferably, in step S1, the core component is doped with at least one rare earth ion of ytterbium, erbium, thulium, neodymium and holmium, or the core component is not doped with rare earth.

[0011] Preferably, in step S1, the difference in thermal expansion coefficients of the core, inner cladding and high-fold ring is within 30%, and the difference in softening temperatures of the core, inner cladding and high-fold ring is within 200°C.

[0012] Preferably, in step S1, the refractive index difference between the high-fold ring and the inner cladding ranges from 0.01 to 0.1.

[0013] Preferably, in step S1, the wall thickness of the high-fold ring is in the range of 0.5-5 μm.

[0014] Preferably, in step S1, the high-fold ring is doped with barium or germanium.

[0015] Compared with the prior art, the method of actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber of the present invention can actively regulate the transmission band and filtering range of an all-solid-state anti-resonant optical fiber by determining an annealing temperature and optimizing an annealing time to obtain a target transmission band and filtering range without affecting its inherent large mode field single-mode transmission characteristics. At the same time, the method has the advantages of low cost, uniform element diffusion, a large adjustable range of the transmission band, and simple operation, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 The present invention is a flow chart of the method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber.

[0018] Figure 2 FIG. 4 is a schematic diagram of the structure of an all-solid-state anti-resonant optical fiber according to an embodiment of the present invention.

[0019] Figure 3 The present invention is a flowchart of a method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to an embodiment of the present invention.

[0020] Figure 4 for Figure 2 The barium element distribution diagram of the high-fold ring after annealing of the all-solid-state antiresonant optical fiber in the embodiment, and the inset on the right is a schematic diagram of the structure of the high-fold ring under a scanning electron microscope.

[0021] Figure 5 for Figure 2 Fiber transmission spectra of the all-solid-state antiresonant fiber before and after annealing in the embodiment. DETAILED DESCRIPTION

[0022] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the following detailed description is given in conjunction with the embodiments.

[0023] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limitations on the present invention.

[0024] See also Figure 1 The method of actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber of the present invention comprises the following steps: S1. Place the all-solid-state anti-resonant optical fiber in a high-temperature furnace, introduce protective gas into the high-temperature furnace and maintain a constant gas flow rate. The all-solid-state anti-resonant optical fiber is composed of a core, an inner cladding and a high-refractive index ring from the inside to the outside. The core is rare earth co-doped or non-rare earth doped glass, the inner cladding is non-rare earth doped glass, the high-refractive index ring is high refractive index glass, and the refractive indices of the core, inner cladding and high-refractive index ring are n respectively. core , n clad and n t , and n t >n clad n core ; S2. Raise the temperature in the high temperature furnace to near the upper annealing temperature limit of the all-solid-state antiresonant optical fiber and maintain it for a certain period of time; S3. Lower the temperature in the high temperature furnace to room temperature and remove the optical fiber; S4. Cure the low-refractive coating on the surface of the cleaned and dried optical fiber.

[0025] Preferably, in step S1, the glass matrix of the core, the inner cladding and the high-fold ring is selected from one of quartz glass, silicate glass, phosphate glass, fluoride glass, chalcogenide glass and tellurite glass.

[0026] Preferably, in step S1, the core component is doped with at least one rare earth ion selected from ytterbium, erbium, thulium, neodymium and holmium, or the core component is not doped with rare earth.

[0027] Preferably, in step S1, the difference in thermal expansion coefficients of the core, inner cladding and high-fold ring is within 30%, and the difference in softening temperatures of the core, inner cladding and high-fold ring is within 200°C.

[0028] Preferably, in step S1, the refractive index difference between the high-fold ring and the inner cladding ranges from 0.01 to 0.1.

[0029] Preferably, in step S1, the wall thickness of the high-fold ring is in the range of 0.5-5 μm.

[0030] Preferably, in step S1, the high-fold ring is doped with barium or germanium to increase the refractive index of the high-fold ring.

[0031] Preferably, in step S2 and step S3, the protective gas in step S1 is continuously introduced, and the gas flow rate is maintained equal to that in step S1. Further, the protective gas is one of oxygen, nitrogen, helium, argon, and carbon dioxide, and the gas flow rate of the protective gas is 0.2-5 L / min.

[0032] Preferably, in step S2, the upper limit temperature of annealing is when the glass viscosity drops to 10 13 The specific value of the temperature at dpa·s depends on the different glass matrices. Generally, the upper annealing temperature of quartz glass is between 1000℃ and 1400℃, the upper annealing temperature of silicate glass is between 500℃ and 700℃, and the upper annealing temperature of phosphate glass is between 400℃ and 600℃; the upper annealing temperature is ±200℃.

[0033] Preferably, in step S2, the temperature in the high temperature furnace is maintained near the upper limit temperature of annealing for a certain period of time ranging from 0.5 to 48 hours. Preferably, in step S3, the time taken to reduce the temperature in the high temperature furnace to room temperature ranges from 1 to 24 hours. As the annealing time increases, the element diffusion becomes more obvious, resulting in more transmission bands and filter shift wavelengths.

[0034] In actual use, the high-temperature furnace is well sealed and free of impurity pollution; the introduction of fluorine, boron, magnesium and other elements into the inner cladding backing glass can reduce the refractive index; the resonant wavelength calculation formula of the all-solid-state anti-resonant optical fiber is: , m is a positive integer, t is the wall thickness of the high-fold ring, and the vicinity of the resonant wavelength is a filter band with a higher transmission loss; the calculation formula for the antiresonant wavelength of the all-solid-state antiresonant optical fiber is: , m is a positive integer, t is the wall thickness of the high-fold ring, the anti-resonance wavelength is the central wavelength of the transmission band, and the transmission loss is low.

[0035] See also Figure 2 , Figure 2 The structure diagram of the all-solid-state antiresonant optical fiber according to an embodiment of the present invention is shown in FIG. The all-solid-state antiresonant optical fiber is composed of a core 1, an inner cladding 2, and a high-fold ring 3 from the inside to the outside. The core 1 is Nd-doped silicate glass, the inner cladding 2 is silicate white glass, and the high-fold ring 3 is high-barium (25 mol%) doped silicate white glass. The refractive indices of the core 1, the inner cladding 2, and the high-fold ring 3 are n respectively. core , n clad and n t , and n t >n clad n core . Scanning electron microscope shows that the fiber structure is complete without obvious defects or bubbles. There are 6 high-fold rings 3, which are evenly distributed in the inner cladding 2 around the core 1, forming a regular polygonal structure. The outer diameter of the fiber is 170μm, the diameter D of the core 1 is 40μm, and the inner diameter d of the high-fold ring 3 is 25.6μm.

[0036] See also Figure 3 , Figure 3 The flowchart of the method for actively regulating the transmission band range of the all-solid-state anti-resonant optical fiber according to one embodiment of the present invention is used for Figure 2 The transmission band and filtering range of the all-solid-state anti-resonant optical fiber in the embodiment are actively regulated. The method comprises the following steps: S1 'the all-solid-state antiresonant optical fiber is placed in a high temperature furnace, argon is introduced into the high temperature furnace, and the gas flow rate is maintained at 1.0L / min; S2 'the high temperature furnace temperature was raised to 560 ℃, respectively, for 2 hours and 4 hours; S3 'after 24 hours the temperature in the high temperature furnace dropped to room temperature, remove the optical fiber; S4'. Curing the low-refractive coating on the cleaned and dried optical fiber surface.

[0037] See also Figure 4 , Figure 4 for Figure 2 The barium element distribution diagram of the high-fold ring after annealing of the all-solid-state antiresonant optical fiber in the embodiment, and the inset is a schematic diagram of the structure of the high-fold ring under a scanning electron microscope. In order to explore the element diffusion, Figure 2 The all-solid-state antiresonant optical fiber in the embodiment was subjected to additional thermal annealing in an argon environment at 560°C for 2 hours and 4 hours respectively to enhance the diffusion of barium between the high-fold ring and the inner cladding backing glass. As the annealing time increases, the diffusion rate of the barium element accelerates, which is characterized by a gradual decrease in the peak intensity of the barium element and a gradual thickening of the high-fold ring. According to the formula: It can be seen that the resonance band will move toward the long-wave direction.

[0038] See also Figure 5 , Figure 5 for Figure 2 Fiber transmission spectra of the all-solid-state antiresonant fiber before and after annealing in the embodiment. Figure 5 The transmission spectra of the 30cm long all-solid anti-resonant fiber in the wavelength range of 0.7μm to 1.45μm are shown before and after thermal annealing at 560℃ in an argon environment for 4 hours. Before thermal annealing, the fiber showed peak loss at 0.99μm, and the loss at 920nm was 7.1dB higher than that at 1060nm. After annealing for 4 hours, the resonance wavelength of the all-solid anti-resonant fiber changed from ~0.99μm to ~1.06μm, thus broadening the high-loss region. In the 30cm long all-solid anti-resonant fiber, the loss at 1060nm was 10.5dB higher than that at 920nm, which is consistent with the designed ~0.9μm fiber laser.

[0039] In summary, the thermal annealing process can actively adjust the transmission band in all-solid-state antiresonant optical fibers.

[0040] The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber of the present invention can actively regulate the transmission band and filtering range of an all-solid-state anti-resonant optical fiber by determining an annealing temperature and optimizing an annealing time to obtain a target transmission band and filtering range without affecting its inherent large mode field single-mode transmission characteristics. At the same time, the method has the advantages of low cost, uniform element diffusion, a large adjustable range of the transmission band, and simple operation, and has broad application prospects.

[0041] The present invention has been described by the above-mentioned relevant embodiments, but the above-mentioned embodiments are only examples for implementing the present invention. In addition, the technical features involved in the different embodiments of the present invention described above can be combined with each other as long as they do not conflict with each other. It must be pointed out that the disclosed embodiments do not limit the scope of the present invention. On the contrary, changes and modifications made without departing from the spirit and scope of the present invention are all within the scope of patent protection of the present invention.

Claims

1. A method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber, characterized in that: The following steps are involved: S1. placing an all-solid-state anti-resonant optical fiber in a high-temperature furnace, introducing a protective gas into the high-temperature furnace and maintaining a constant gas flow rate, wherein the all-solid-state anti-resonant optical fiber is composed of a core, an inner cladding and a high-fold ring from the inside to the outside, wherein the core is rare earth co-doped or non-rare earth doped glass, the inner cladding is non-rare earth doped glass, the high-fold ring is high refractive index glass, and the refractive indices of the core, inner cladding and high-fold ring are n respectively. core , n clad and n t , and n t >n clad n core ; S2. Raise the temperature in the high temperature furnace to near the upper annealing temperature limit of the all-solid-state antiresonant optical fiber and maintain it for a certain period of time; S3. Lower the temperature in the high temperature furnace to room temperature and remove the optical fiber; S4. Cure the low-refractive coating on the cleaned and dried optical fiber surface.

2. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S1, the glass matrix of the core, inner cladding and high-fold ring is selected from one of quartz glass, silicate glass, phosphate glass, fluoride glass, chalcogenide glass and tellurite glass.

3. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S2 and step S3, the protective gas in step S1 is continuously introduced, and the gas flow rate is maintained equal to that in step S1.

4. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber as claimed in claim 3, characterized in that: The protective gas is one of oxygen, nitrogen, helium, argon and carbon dioxide, and the gas flow rate of the protective gas is 0.2-5L / min.

5. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S2, the upper limit temperature of annealing is when the glass viscosity drops to 10 13 The temperature at dpa·s is ±200°C of the annealing upper limit temperature.

6. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S2, the temperature in the high temperature furnace is maintained near the upper limit temperature of annealing for a certain time in the range of 0.5-48 hours.

7. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S3, the time taken to reduce the temperature in the high-temperature furnace to room temperature ranges from 1 to 24 hours.

8. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S1, the core component is doped with at least one rare earth ion selected from ytterbium, erbium, thulium, neodymium and holmium, or the core component is not doped with rare earth.

9. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S1, the difference in thermal expansion coefficients of the core, inner cladding and high-fold ring is within 30%, and the difference in softening temperatures of the core, inner cladding and high-fold ring is within 200°C.

10. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S1, the refractive index difference between the high-fold ring and the inner cladding ranges from 0.01 to 0.

1.

11. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S1, the wall thickness of the high-fold ring is in the range of 0.5-5 μm.

12. The method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, characterized in that: In step S1, the high-fold ring is doped with barium or germanium.

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