Method for actively regulating the transmission band range of all-solid-state antiresonant optical fiber

Abstract

The present invention provides a method for actively regulating the transmission band range of an all-solid-state antiresonant optical fiber. The method comprises the following steps: placing the all-solid-state antiresonant optical fiber in a high-temperature furnace, introducing a protective gas into the furnace and maintaining a constant gas flow rate; raising the temperature in the furnace to near the upper annealing temperature of the all-solid-state antiresonant optical fiber and maintaining the temperature for a predetermined period of time; lowering the temperature in the furnace to room temperature and removing the optical fiber; and curing a low-refractive index coating on the surface of the cleaned and dried optical fiber. This method, by determining the annealing temperature and optimizing the annealing time to obtain the target transmission band and filtering range, can actively regulate the transmission band and filtering range of the all-solid-state antiresonant optical fiber without affecting its inherent large-mode-field single-mode transmission characteristics. Furthermore, the method has the advantages of low cost, uniform element diffusion, a wide adjustable transmission band range, and simple operation, and has broad application prospects.

Description

Technical Field

[0001] The present 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 combine the characteristics of large-mode-area single-mode transmission with distributed filtering, and have broad application prospects in high-power fiber lasers and amplifiers. Unlike hollow-core antiresonant fibers, all-solid-state antiresonant fibers utilize a glass core and inner cladding. By manipulating the thickness and refractive index of the high-fold ring, the range of the resonance band and transmission band can be controlled. This allows for distributed filtering while ensuring large-mode-area transmission. In recent years, the design, fabrication, and laser performance of all-solid-state antiresonant fibers have garnered widespread 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 inevitably be accompanied by element diffusion, which will change the refractive index distribution and thickness of the high-fold ring. According to the resonant wavelength calculation formula: This can be seen to affect the transmission band and filtering range of all-solid-state antiresonant fibers. This element diffusion process is often difficult to precisely control and has a significant impact on fiber laser performance. Summary of the Invention

[0004] In response to the above technical problems, the present invention provides a method for actively regulating the transmission band range of an all-solid-state antiresonant optical fiber. This 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. It is suitable for the field of high-power 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:

[0006] S1. Place an all-solid-state anti-resonant optical fiber in a high-temperature furnace, introduce a protective gas into the 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 out. The core is made of rare earth co-doped or non-rare earth doped glass, the inner cladding is made of non-rare earth doped glass, and the high-refractive index ring is made of high-refractive index glass. 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 ;

[0007] S2. Raise the temperature in the high-temperature furnace to near the upper annealing temperature of the all-solid-state antiresonant fiber and maintain it for a certain period of time;

[0008] S3. Lower the temperature in the high-temperature furnace to room temperature and remove the optical fiber;

[0009] S4. Cure the low-refractive index coating on the cleaned and dried optical fiber surface.

[0010] Preferably, 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.

[0011] Preferably, in steps S2 and S3, the protective gas in step S1 is continuously introduced and the gas flow rate is maintained equal to that in step S1. Furthermore, 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.

[0012] 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.

[0013] Preferably, in step S2, the temperature in the high temperature furnace is kept near the upper limit of annealing temperature for a certain time in the range of 0.5-48 hours.

[0014] 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.

[0015] 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.

[0016] Preferably, in step S1, the difference in thermal expansion coefficients of the fiber core, inner cladding and high-fold ring is within 30%, and the difference in softening temperatures of the fiber core, inner cladding and high-fold ring is within 200°C.

[0017] Preferably, in step S1 , the refractive index difference between the high-fold ring and the inner cladding ranges from 0.01 to 0.1.

[0018] Preferably, in step S1, the wall thickness of the high-fold ring is in the range of 0.5-5 μm.

[0019] Preferably, in step S1 , the high-fold ring is doped with barium or germanium.

[0020] Compared with the prior art, the method of the present invention for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber can actively regulate the transmission band and filtering range of an all-solid-state anti-resonant optical fiber by determining the annealing temperature and optimizing the annealing time to obtain the target transmission band and filtering range without affecting its inherent large mode field single-mode transmission characteristics. At the same time, this method has the advantages of low cost, uniform element diffusion, a large adjustable transmission band range, and simple operation, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 This is a flow chart of the method for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber according to the present invention.

[0023] Figure 2 Schematic diagram of the structure of an all-solid-state antiresonant optical fiber according to an embodiment of the present invention.

[0024] Figure 3 This is a flow chart 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.

[0025] 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. The illustration on the right is a schematic structural diagram of the high-fold ring under a scanning electron microscope.

[0026] Figure 5 for Figure 2 Fiber transmission spectra of the all-solid-state antiresonant fiber before and after annealing in the embodiment. DETAILED DESCRIPTION

[0027] In order to provide a further understanding of the purpose, structure, features, and functions of the present invention, the present invention is described in detail below with reference to the embodiments.

[0028] In the description of the present invention, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating directions or positional relationships, are 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 limiting the present invention.

[0029] See 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:

[0030] S1. Place an all-solid-state anti-resonant optical fiber in a high-temperature furnace, introduce a protective gas into the 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 out. The core is made of rare earth co-doped or non-rare earth doped glass, the inner cladding is made of non-rare earth doped glass, and the high-refractive index ring is made of high-refractive index glass. 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 ;

[0031] S2. Raise the temperature in the high-temperature furnace to near the upper annealing temperature of the all-solid-state antiresonant fiber and maintain it for a certain period of time;

[0032] S3. Lower the temperature in the high-temperature furnace to room temperature and remove the optical fiber;

[0033] S4. Cure the low-refractive index coating on the cleaned and dried optical fiber surface.

[0034] Preferably, 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.

[0035] 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.

[0036] Preferably, in step S1, the difference in thermal expansion coefficients of the fiber core, inner cladding and high-fold ring is within 30%, and the difference in softening temperatures of the fiber core, inner cladding and high-fold ring is within 200°C.

[0037] Preferably, in step S1, the refractive index difference between the high-fold ring and the inner cladding ranges from 0.01 to 0.1.

[0038] Preferably, in step S1, the wall thickness of the high-fold ring is in the range of 0.5-5 μm.

[0039] Preferably, in step S1, the high-fold ring is doped with barium or germanium to increase the refractive index of the high-fold ring.

[0040] 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. Furthermore, 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.

[0041] 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 substrates. 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 around ±200℃.

[0042] Preferably, in step S2, the temperature in the high temperature furnace is kept near the upper limit of annealing temperature for a certain time in the range of 0.5-48 hours.

[0043] 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.

[0044] In actual use, the high-temperature furnace is well sealed and free of impurities. Introducing elements such as fluorine, boron, and magnesium into the inner cladding backing glass can reduce the refractive index. The resonant wavelength calculation formula of the all-solid-state antiresonant 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 high transmission loss. The calculation formula for the antiresonant wavelength of the all-solid-state antiresonant fiber is: , m is a positive integer, t is the wall thickness of the high-fold ring, the anti-resonance wavelength is the center wavelength of the transmission band, and the transmission loss is low.

[0045] See Figure 2 , Figure 2 The structure 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 comprises, from the inside to the outside, a core 1, an inner cladding 2, and a high-fold ring 3. The core 1 is made of Nd-doped silicate glass, the inner cladding 2 is made of silicate white glass, and the high-fold ring 3 is made of high-barium (25 mol%) doped silicate white glass. The refractive indices of the core 1, inner cladding 2, and high-fold ring 3 are n=1, n=2, and n=3, respectively. core , n clad and n t , and n t >n clad n coreScanning electron microscopy reveals that the fiber is structurally intact, with no apparent defects or bubbles. Six high-fold rings 3 are evenly distributed within the inner cladding 2 surrounding the fiber core 1, forming a regular polygonal structure. The fiber's outer diameter is 170 μm, the core 1's diameter D is 40 μm, and the inner diameter d of the high-fold rings 3 is 25.6 μm.

[0046] See Figure 3 , Figure 3 This is a flow chart 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, Figure 2 The transmission band and filtering range of the all-solid-state antiresonant optical fiber in the embodiment are actively regulated. The method includes the following steps:

[0047] S1 '. The all-solid-state antiresonant 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;

[0048] S2 '. The high temperature furnace temperature was raised to 560 ℃, respectively, for 2 hours and 4 hours;

[0049] S3 'after 24 hours the high temperature furnace temperature dropped to room temperature, remove the optical fiber;

[0050] S4'. Curing the low-refractive index coating on the cleaned and dried optical fiber surface.

[0051] See 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 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 fiber in the embodiment was subjected to additional thermal annealing in an argon atmosphere 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 barium accelerates, characterized by a gradual decrease in the peak intensity of the barium element and a gradual increase in the thickness of the high-fold ring. According to the formula: It can be seen that the resonance band will shift toward the long-wave direction.

[0052] See 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 5The transmission spectra of a 30 cm long all-solid-state antiresonant fiber in the wavelength range of 0.7 μm to 1.45 μm are shown before and after thermal annealing at 560°C for 4 hours in an argon atmosphere. Before thermal annealing, the fiber exhibited peak loss at 0.99 μm, and the loss at 920 nm was 7.1 dB higher than that at 1060 nm. After annealing for 4 hours, the resonant wavelength of the all-solid-state antiresonant fiber shifted from ~0.99 μm to ~1.06 μm, broadening the high-loss region. In the 30 cm long all-solid-state antiresonant fiber, the loss at 1060 nm was 10.5 dB higher than that at 920 nm, consistent with the designed ~0.9 μm fiber laser.

[0053] In summary, the thermal annealing process can actively adjust the transmission band in all-solid-state antiresonant optical fibers.

[0054] The method of the present invention for actively regulating the transmission band range of an all-solid-state anti-resonant optical fiber determines the annealing temperature and optimizes the annealing time to obtain the target transmission band and filtering range. This method can actively regulate the transmission band and filtering range of the all-solid-state anti-resonant optical fiber without affecting its inherent large-mode-field single-mode transmission characteristics. Furthermore, the method has the advantages of low cost, uniform element diffusion, a large adjustable transmission band range, and simple operation, and has broad application prospects.

[0055] The present invention has been described using the above-described embodiments. However, these embodiments are merely exemplary embodiments of the present invention. Furthermore, the technical features described above in the various embodiments of the present invention may be combined as long as they do not conflict with each other. It should be noted that the disclosed embodiments do not limit the scope of the present invention. On the contrary, modifications and enhancements made without departing from the spirit and scope of the present invention are within the scope of patent protection.

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. Place the high-temperature drawn all-solid-state anti-resonant optical fiber in a high-temperature furnace, introduce a protective gas into the high-temperature furnace and maintain 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-refractive index ring from the inside out, 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-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. The high temperature furnace temperature is raised to near the upper limit annealing temperature of the all-solid-state antiresonant optical fiber and maintained for a certain time, wherein the high temperature furnace temperature is maintained near the upper limit annealing temperature for a certain time in the range of 0.5 to 48 hours; S3. The high temperature furnace temperature is lowered to room temperature, the optical fiber is removed, and the high temperature furnace temperature is lowered to room temperature for a period of time ranging from 1 to 24 hours; S4. Curing the low-fold coating on the cleaned and dried optical fiber surface; Wherein, as the annealing time of the all-solid-state anti-resonance optical fiber increases, the element diffusion between the high-fold ring and the inner cladding is enhanced, so that the transmission band of the all-solid-state anti-resonance optical fiber shifts more wavelengths.

2. The method for actively controlling the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, wherein: 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 controlling the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, wherein: 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 controlling the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 3, wherein: 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 to 5 L / min.

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

6. The method for actively controlling the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, wherein: 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.

7. The method for actively controlling the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, wherein: 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.

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

1.

9. The method for actively controlling the transmission band range of an all-solid-state anti-resonant optical fiber according to claim 1, wherein: In step S1, the wall thickness of the high-fold ring ranges from 0.5 to 5 μm.

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

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