Glass optical fiber with an extra-large core diameter and method of manufacture

Abstract

The embodiment of the application discloses a large-core glass optical fiber and a manufacturing method, the large-core glass optical fiber comprises: a multi-component core layer glass and a cladding glass, wherein: the cladding glass is cylindrical, and the cladding glass is provided with a through hole in the length direction; the multi-component core layer glass is cylindrical, and the shape of the multi-component core layer glass matches the shape of the through hole of the cladding glass, and the multi-component core layer glass is arranged in the through hole of the cladding glass. By arranging the multi-component core layer glass and the cladding glass, the manufacturing process is simple, the multi-component core layer glass is arranged in the cladding glass, the core radius and the cladding radius of the glass optical fiber can be improved, the stimulated Brillouin threshold of a high-power single-frequency narrow-line-width optical fiber laser is improved, and the problems of various optical nonlinear effects and unstable laser output modes of the existing optical fiber are solved.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of optical fiber manufacturing, in particular to a glass optical fiber with an ultra-large core diameter and a manufacturing method. BACKGROUND

[0002] In recent years, high-power single-frequency narrow linewidth fiber lasers have attracted extensive attention of researchers at home and abroad due to their important application value in the fields of ultra-high precision laser radar, fiber sensing, space communication and fiber communication. However, with the continuous development of fiber lasers to higher power, the nonlinear effect and mode instability effect under high-power pumping become a great obstacle to the development. In order to reduce the nonlinear effect in the optical fiber, the core diameter of the optical fiber needs to be increased, but the increase of the core diameter of the optical fiber will lead to the increase of the mode of the optical fiber, the output of the single mode changes to the multi-mode, and the laser beam quality is reduced. Since the ultra-large core diameter optical fiber can make the thermal load of the optical fiber decrease in a square rate, effectively eliminate various problems caused by thermal effects, increase the power tolerance of the optical fiber, and greatly improve the output energy of the fiber laser. Therefore, it is a feasible method to realize the single-mode operation of the ultra-large core diameter optical fiber by reducing the numerical aperture of the optical fiber. Combined with the power requirement of the development of the single-frequency narrow linewidth fiber laser, it is particularly important to carry out new formula design and manufacturing method optimization on the gain optical fiber under the existing overall design framework of the fiber laser.

[0003] Researchers at home and abroad have carried out a large number of researches. At present, domestic researchers have prepared aluminum-phosphorus-silicon ternary system single-mode optical fibers by using new technology, the refractive index difference of the core and cladding material is Δn=0.0004, NA=0.036, the core diameter D=25μm, and the beam quality factor M2=1.12. Domestic researchers also prepared quartz optical fibers by using the sol-gel method, NA=0.02, D=50μm, and M2<1.1. In addition, foreign researchers proposed a single-groove 30μm large core diameter single-mode optical fiber, foreign researchers also proposed the concept of spiral core optical fiber, which can realize 50μm large core diameter while effectively suppressing high-order modes to obtain nearly strict single-mode output; foreign researchers also proposed a large-pitch photonic crystal fiber with a core diameter of 54μm. The unique high-order mode delocalization effect of this kind of optical fiber makes the gain obtained by the high-order mode very small, thereby realizing effective high-order mode suppression. However, the above-mentioned optical fibers generally have problems such as complex preparation process, poor bending resistance and difficulty in fusion splicing with existing commercial optical fibers, which greatly limits the popularization and application of new structure optical fibers.

[0004] In summary, the existing large core diameter and low numerical aperture optical fibers still have many technical bottlenecks and cannot meet the requirements of batch production. In particular, the research on large core diameter and low numerical aperture high-rare earth doped (high gain) multi-component glass optical fibers is still blank. SUMMARY

[0005] Embodiments of the present application provide a large core diameter glass optical fiber and a manufacturing method to solve or partially solve the above problems.

[0006] Other features and advantages of the present application will become apparent from the following detailed description, or will be learned by practice of the present application.

[0007] According to an aspect of embodiments of the present application, a large core diameter glass optical fiber is provided, the large core diameter glass optical fiber comprising: a multi-component core layer glass and a cladding glass, wherein: the cladding glass is cylindrical, and the cladding glass is provided with a through hole in the length direction; the multi-component core layer glass is cylindrical, and the shape of the multi-component core layer glass matches the shape of the through hole of the cladding glass, and the multi-component core layer glass is arranged in the through hole of the cladding glass.

[0008] In some examples, the material of the multi-component core layer glass comprises: silicon dioxide and rare earth oxide.

[0009] In some examples, the material of the multi-component core layer glass further comprises: at least one of yttrium oxide, calcium oxide, strontium oxide, lithium oxide, sodium oxide, potassium oxide, and zinc fluoride.

[0010] In some examples, the content of the silicon dioxide in the multi-component core layer glass is 3 to 7 mole percent.

[0011] In some examples, the material of the multi-cladding glass comprises: silicon dioxide; and the material of the multi-component core layer glass further comprises at least one of aluminum oxide, boron trioxide, lanthanum oxide, germanium dioxide, calcium oxide, strontium oxide, potassium oxide, and sodium oxide.

[0012] According to an aspect of embodiments of the present application, a manufacturing method of a large core diameter glass optical fiber is provided, the manufacturing method comprising: melting a multi-component core layer glass and a cladding glass; machining the multi-component core layer glass into a cylindrical rod and polishing the surface of the multi-component core layer glass; mechanically punching the cladding glass and polishing the inner surface of the hole of the cladding glass; inserting the multi-component core layer glass into the punched cladding glass to obtain an optical fiber preform, and machining the optical fiber preform to obtain the large core diameter glass optical fiber.

[0013] In some examples, the machining of the optical fiber preform to obtain the large core diameter glass optical fiber comprises: drawing the optical fiber preform at a target temperature to obtain the large core diameter glass optical fiber, and the target temperature is in the range of 1000 to 1250 degrees.

[0014] In the technical scheme provided in the embodiment of the present application, the super-large core diameter glass optical fiber comprises: a multi-component core layer glass and a cladding glass, wherein: the cladding glass is in a cylindrical shape, and the cladding glass is provided with a through hole in the length direction; the multi-component core layer glass is in a cylindrical shape, and the shape of the multi-component core layer glass matches the shape of the through hole of the cladding glass, and the multi-component core layer glass is arranged in the through hole of the cladding glass. By arranging the multi-component core layer glass and the cladding glass, the manufacturing process is simple, and the core radius and the cladding radius of the glass optical fiber can be improved by arranging the multi-component core layer glass in the cladding glass, thereby improving the stimulated Brillouin threshold of the high-power single-frequency narrow-line-width optical fiber laser, and solving the problems of various optical nonlinear effects and unstable laser output mode of the existing optical fiber.

[0015] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 FIG. 1 is a basic structure schematic diagram of a super-large core diameter glass optical fiber according to an exemplary embodiment of the present application;

[0017] Figure 2 FIG. 2 is a basic flow schematic diagram of a manufacturing method of a super-large core diameter glass optical fiber according to an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0018] The exemplary embodiments will be described in detail herein below with reference to the accompanying drawings. In the following description, the same numbers in different drawings represent the same or similar elements unless otherwise represented. The embodiments described in the following exemplary embodiments do not represent all the embodiments consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0019] The block diagram shown in the accompanying drawings is only a functional entity, and does not necessarily correspond to a physically independent entity. That is, the functional entity can be implemented in the form of software, or in one or more hardware modules or integrated circuits, or in different network and / or processor devices and / or microcontroller devices.

[0020] The flowchart shown in the accompanying drawings is only an exemplary description, and does not necessarily include all the contents and operations / steps, nor does it necessarily execute in the order described. For example, some operations / steps can be further divided, and some operations / steps can be combined or partially combined, so that the actual execution order can be changed according to the actual situation.

[0021] It should be noted that the "multiple" mentioned in the present application refers to two or more than two. The "and / or" describes the association relationship of the associated objects, which means that there can be three relationships, for example, A and / or B can represent the three cases of A alone, A and B together, and B alone. The character " / " generally represents an "or" relationship between the associated objects before and after it.

[0022] As shown in Figure 1 Figure 1 is a super-large core diameter glass optical fiber according to an embodiment of the present application, which comprises: a multi-component core layer glass 1 and a cladding glass 2, wherein: the cladding glass 2 is cylindrical, and the cladding glass 2 is provided with a through hole in the length direction; the multi-component core layer glass 1 is cylindrical, and the shape of the multi-component core layer glass 1 matches the shape of the through hole of the cladding glass 2, and the multi-component core layer glass 1 is arranged in the through hole of the cladding glass 2.

[0023] Among them, the glass optical fiber provided by the present example has simple manufacturing process, and the multi-component core layer glass is arranged in the cladding glass, which can improve the core radius and cladding radius of the glass optical fiber, thereby improving the stimulated Brillouin threshold of the high-power single-frequency narrow-line-width optical fiber laser, and solving the problems of various optical nonlinear effects and unstable laser output mode existing in the existing optical fiber.

[0024] Among them, the diameter of the multi-component core layer glass 1 is ≥50μm, the diameter of the cladding glass 2 is ≥250μm, and the numerical aperture NA is ≤0.05.

[0025] In some examples, the material of the multi-component core layer glass 1 comprises: silicon dioxide and rare earth oxide. The material of the multi-component core layer glass 1 further comprises: at least one of yttrium trioxide, calcium oxide, strontium oxide, lithium oxide, sodium oxide, potassium oxide and zinc fluoride. In some examples, the content of the silicon dioxide in the multi-component core layer glass 1 is 3-7 mole percent.

[0026] ​In the above example, the multi-component core layer glass 1 is a high-concentration rare earth ion doped multi-component silicate glass, mainly comprising the following components: silicon dioxide SiO2, yttrium trioxide Y2O3, calcium oxide CaO, strontium oxide SrO, lithium oxide Li2O, sodium oxide (Na2O, potassium oxide K2O, zinc fluoride ZnF2, rare earth oxide RE2O3 (RE = Er3+, Tm3+, Yb3+), wherein SiO2 and RE2O3 are indispensable components, and the content of RE2O3 is x = 3-7 mol.%. In addition, the glass composition further comprises at least 4 other components, and the total content of the above components except RE2O3 is (100-x) mol.%.

[0027] In some examples, the material of the multi-cladding layer glass 2 comprises silicon dioxide, and the material of the multi-component core layer glass 1 further comprises at least one of aluminum oxide, boron trioxide, lanthanum oxide, germanium dioxide, calcium oxide, strontium oxide, potassium oxide, and sodium oxide.

[0028] In the above example, the cladding layer glass 2 is a multi-component silicate glass, mainly comprising the following components: SiO2, aluminum oxide Al2O3, boron trioxide B2O3, lanthanum oxide La2O3, germanium dioxide GeO2, calcium oxide CaO, strontium oxide SrO, potassium oxide K2O, and sodium oxide Na2O, wherein SiO2 is an indispensable component, and in addition, at least 4 other components are included, and the total content of the components is 100 mol.%.

[0029] According to an aspect of an embodiment of the present application, a manufacturing method of a glass optical fiber with an extra-large core diameter is provided, as shown in Figure 2 The manufacturing method comprises the following steps:

[0030] S101, melting the multi-component core layer glass 1 and the cladding layer glass 2;

[0031] S102, mechanically processing the multi-component core layer glass 1 into a cylindrical rod, and polishing the surface of the multi-component core layer glass 1;

[0032] S103, mechanically punching the cladding layer glass 2, and polishing the inner surface of the hole of the cladding layer glass 2;

[0033] S104, inserting the multi-component core layer glass 1 into the punched cladding layer glass 2 to obtain an optical fiber preform, and processing the optical fiber preform to obtain the glass optical fiber with an extra-large core diameter.

[0034] In some examples, the processing of the optical fiber preform to obtain the large-core glass optical fiber includes: drawing the optical fiber preform at a target temperature to obtain the large-core glass optical fiber, the target temperature being in a range of 1000 to 1250 degrees.

[0035] Specifically, first, a high-concentration rare earth ion doped multi-component core layer glass 1 and a cladding layer glass 2 without rare earth ion doping are fused in a temperature range of 1450-1650℃; then the multi-component core layer glass 1 is mechanically processed into a cylindrical rod with a proper size and the surface thereof is polished; the cladding layer glass 2 is mechanically punched and the inner surface of the hole thereof is polished; finally, the core layer glass cylindrical rod is inserted into the punched cladding layer glass 2 to obtain an optical fiber preform, and then the optical fiber is drawn by using an optical fiber drawing tower in a temperature range of 1000-1250℃.

[0036] In order to better understand the present application, more specific examples are provided in the embodiments for illustration:

[0037] It can be understood that the nonlinear effect of the optical fiber is closely related to its composition in nature, for example, in the case of stimulated Brillouin scattering (SBS), Brillouin scattering is caused by the interaction of the optical field and the acoustic field in the optical fiber, and the theoretical gain coefficient gB can be expressed as:

[0038]

[0039] Wherein, n is the refractive index of the optical fiber, p12 is the transverse photoelastic coefficient, c is the speed of light, ρ is the density, υa is the acoustic velocity, and ΔυB is the Brillouin scattering linewidth. As can be seen from the formula, the smaller the photoelastic coefficient p12 of the optical fiber, the smaller the Brillouin scattering gain coefficient. For multi-component glass, the influence of the mixing of various elements on the overall performance of the optical fiber can be analyzed by the macroscopic continuum model proposed by Winklemann and Schott. By introducing elements with negative photoelastic coefficient into the optical fiber, the p12 can be reduced, and even p12=0, i.e. "ideal" optical fiber without Brillouin scattering can be obtained.

[0040] In the following embodiments, in order to reduce the Brillouin gain coefficient gB of the large-core, ultra-low numerical aperture multi-component silicate glass optical fiber, elements with negative photoelastic coefficient such as Y2O3, CaO, K2O, Na2O, Yb2O3, etc. are introduced into the composition of the optical fiber, which significantly reduces the photoelastic coefficient p12 of the optical fiber. Therefore, compared with the traditional single-mode optical fiber, the stimulated Brillouin scattering threshold of the large-core, ultra-low numerical aperture multi-component silicate optical fiber is greatly improved.

[0041] The problem of mode instability (TMI) of fiber laser caused by thermal induced refractive index grating can also be solved by means of modulated composition. Studies show that the formation of thermal induced refractive index grating is closely related to the thermo-optic effect of fiber material, and the theoretical threshold Pth of fiber mode instability is:

[0042]

[0043] wherein dn / dT is the thermal-optic coefficient of the fiber, cp is the specific heat, and the term in the parentheses represents the degree of quantum loss, and the F function is related to the degree of mode overlap and frequency distribution. As can be seen, the TMI threshold can be increased by reducing the thermal-optic coefficient of the fiber. By introducing elements with negative thermal-optic coefficient into the fiber, such as SrO, Na2O, K2O, ZnF2, etc., the thermal-optic coefficient of the fiber can be reduced, thereby increasing the mode instability threshold of the fiber.

[0044] In order to reduce the mode instability threshold Pth of the super-large core diameter and ultra-low numerical aperture multi-component silicate glass fiber, elements with negative thermal-optic coefficient such as SrO, Na2O, K2O, ZnF2, etc. are introduced into the fiber composition, which significantly reduces the thermal-optic coefficient dn / dT of the fiber. In addition, as can be seen from the formula, reducing the quantum loss degree of the fiber laser can also increase the TMI threshold, therefore, by designing appropriate rare earth doped modes and pump source modes, the quantum loss degree can be reduced, and the TMI threshold can be further increased.

[0045] The above super-large core diameter glass fiber is analyzed and described below through specific examples.

[0046] Example 1

[0047] In this embodiment, the near-infrared luminescent ion doped in the super-large core diameter and ultra-low numerical aperture fiber is Yb3+, and the specific preparation steps are as follows:

[0048] (1) melt multi-component core layer glass 1 at 1650℃, the composition is: 62SiO2-5Y2O3-5CaO-5SrO-5K2O-10Na2O-5ZnF2-3Yb2O3, pour the glass into a large block, and perform precision annealing to eliminate thermal stress;

[0049] (2) melt cladding glass 2 at 1650℃, the composition is: 62SiO2-5Y2O3-5CaO-5SrO-5K2O-15Na2O-3B2O3, pour the glass into a large block, and perform precision annealing to eliminate thermal stress;

[0050] (3) mechanically process the multi-component core layer glass 1 into a glass rod with a diameter of 5.0mm by numerical control lathe, and polish the outer surface thereof;

[0051] (4) The clad glass 2 is mechanically processed into a glass rod with a diameter of 22.73 mm by a numerical control lathe, and the outer surface is polished;

[0052] (5) A mechanical hole is punched at the center of the clad glass 2 rod, with a hole diameter of 5.2 mm, and the inner surface of the hole is polished;

[0053] (6) The optical fiber is drawn at 1250°C by using a drawing tower, and finally an optical fiber with a core diameter of 55 μm and a clad diameter of 250 μm is obtained.

[0054] The refractive index of the core and clad glass 2 is tested by using a Metricon Model 2010 prism coupling instrument, and the numerical aperture of the optical fiber is calculated to be 0.04.

[0055] Example 2

[0056] In this embodiment, the doped near-infrared luminescent ions of the super-large core diameter and super-low numerical aperture optical fiber are Er3+, and the specific preparation steps are as follows:

[0057] (1) The multi-component core glass 1 is melted at 1550°C, and the composition is: 55SiO2-4Y2O3-3SrO-3Al2O3-5GeO2-5CaO-5K2O-10Na2O-5ZnF2-5Er2O3, the glass is poured into a large block of glass, and precise annealing is carried out to eliminate thermal stress;

[0058] (2) The clad glass 2 is melted at 1550°C, and the composition is: 55SiO2-9Y2O3-3SrO-3Al2O3-5GeO2-5CaO-5K2O-15Na2O, the glass is poured into a large block of glass, and precise annealing is carried out to eliminate thermal stress;

[0059] (3) The multi-component core glass 1 is mechanically processed into a glass rod with a diameter of 5.0 mm by a numerical control lathe, and the outer surface is polished;

[0060] (4) The clad glass 2 is mechanically processed into a glass rod with a diameter of 22.73 mm by a numerical control lathe, and the outer surface is polished;

[0061] (5) A mechanical hole is punched at the center of the clad glass 2 rod, with a hole diameter of 5.2 mm, and the inner surface of the hole is polished;

[0062] (6) The optical fiber is drawn at 1100°C by using a drawing tower, and finally an optical fiber with a core diameter of 55 μm and a clad diameter of 250 μm is obtained.

[0063] The refractive index of the core layer and the cladding glass 2 is tested by using Metricon Model 2010 prism coupling instrument, and the numerical aperture of the optical fiber is calculated as 0.045. Compared with the commercial G.652 optical fiber, the stimulated Brillouin scattering threshold of the optical fiber disclosed in the application is increased by 3.5 times.

[0064] Example 3

[0065] In the embodiment, the near-infrared luminescent ion doped in the super-large core diameter and super-low numerical aperture optical fiber is Tm3+, and the specific preparation steps are as follows:

[0066] (1) The multi-component core layer glass 1 is fused at 1450℃, and the composition is 50SiO2-5Y2O3-5Al2O3-5CaO-5SrO-10K2O-8Na2O-5ZnF2-7.0Tm2O3, the glass is poured into a large block of glass, and precision annealing is carried out to eliminate thermal stress;

[0067] (2) The cladding glass 2 is fused at 1450℃, and the composition is 50SiO2-8Y2O3-5Al2O3-5CaO-5SrO-10K2O-14Na2O-3B2O3, the glass is poured into a large block of glass, and precision annealing is carried out to eliminate thermal stress;

[0068] (3) The multi-component core layer glass 1 is mechanically processed into a glass rod with a diameter of 5.0mm by using a numerical control lathe, and the outer surface is polished;

[0069] (4) The cladding glass 2 is mechanically processed into a glass rod with a diameter of 22.73mm by using a numerical control lathe, and the outer surface is polished;

[0070] (5) A mechanical hole is made in the center of the cladding glass 2 rod, and the hole diameter is 5.2mm, and the inner surface of the hole is polished;

[0071] (6) The optical fiber is drawn by using a drawing tower at 1000℃, and finally an optical fiber with a core diameter of 55μm and a cladding diameter of 250μm is obtained.

[0072] The refractive index of the core layer and the cladding glass 2 is tested by using Metricon Model 2010 prism coupling instrument, and the numerical aperture of the optical fiber is calculated as 0.05. Compared with the commercial G.652 optical fiber, the stimulated Brillouin scattering threshold of the optical fiber disclosed in the application is increased by 4 times.

[0073] The example discloses a large core diameter, ultra-low numerical aperture multi-component silicate glass optical fiber and a preparation method thereof, the preparation method comprising the following steps: preparing a high-concentration rare earth ion doped multi-component silicate glass; preparing a cladding glass 2 matched with the performance thereof; preparing an optical fiber preform rod by adopting a tube rod method, and drawing the large core diameter, ultra-low numerical aperture multi-component silicate glass optical fiber by using an optical fiber drawing tower.

[0074] Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the embodiments disclosed herein. It is intended that the specification and examples be considered as exemplary only, with the true scope of the application being indicated by the following claims.

[0075] The above description is only the preferred exemplary embodiment of the present application, and is not intended to limit the implementation of the present application, and those skilled in the art can easily make corresponding changes or modifications according to the main idea and spirit of the present application, and therefore the protection scope of the present application should be subject to the protection scope required by the claims.

Claims

1. A method for fabricating glass optical fibers with ultra-large core diameter and ultra-low numerical aperture, characterized in that, The manufacturing method includes: Fusing multi-component core glass and cladding glass; The multi-component core glass is machined into a cylindrical rod, and the surface of the multi-component core glass is polished. The cladding glass is mechanically drilled, and the inner surface of the hole in the cladding glass is polished. The multi-component core glass is inserted into the cladding glass after drilling to obtain an optical fiber preform, and the optical fiber preform is processed to obtain the glass optical fiber. Near-infrared luminescent ions doped with Yb in ultra-large core diameter, ultra-low numerical aperture optical fibers 3+ In the case of melting multi-component core glass and cladding glass, the process includes: melting multi-component core glass at 1650°C with the composition: 62SiO2-5Y2O3-5CaO-5SrO-5K2O-10Na2O-5ZnF2-3Yb2O3; casting the glass into a large glass block; and performing precision annealing to eliminate thermal stress; melting cladding glass at 1650°C with the composition: 62SiO2-5Y2O3-5CaO-5SrO-5K2O-15Na2O-3B2O3; casting the glass into a large glass block; and performing precision annealing to eliminate thermal stress.

2. The method for fabricating glass optical fibers with ultra-large core diameter and ultra-low numerical aperture according to claim 1, characterized in that, The process of processing the optical fiber preform to obtain the glass optical fiber includes: The glass fiber is obtained by drawing the optical fiber preform at a target temperature, wherein the target temperature ranges from 1000 to 1250 degrees.

3. A glass optical fiber with an ultra-large core diameter and ultra-low numerical aperture, characterized in that, It is prepared using the fabrication method of ultra-large core diameter and ultra-low numerical aperture glass optical fiber as described in any one of claims 1-2.

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