Erbium-doped optical fiber, preparation method thereof and erbium-doped optical fiber amplifier

Abstract

The invention provides an erbium-doped optical fiber, a preparation method thereof and an erbium-doped optical fiber amplifier, the erbium-doped optical fiber comprises a fiber core, the fiber core comprises a silicon dioxide matrix, an erbium element and a zirconium element, the erbium element and the zirconium element exist in the silicon dioxide matrix, and the mass percentage content of the zirconium element in the fiber core is 0.01%-5%. According to the invention, the gain bandwidth and gain performance of the erbium-doped fiber can be improved, and the noise is reduced.

Description

Technical Field

[0001] This invention relates to the field of optical communication, specifically to an erbium-doped optical fiber, its preparation method, and an erbium-doped optical fiber amplifier. Background Technology

[0002] With the increase in transmission capacity, higher requirements are placed on the operating bandwidth of optical fibers. For example, erbium-doped fiber, as a key material in erbium-doped fiber amplifiers (EDFAs), needs to have its gain performance and gain bandwidth improved simultaneously. However, in related technologies, erbium-doped fibers generally suffer from problems such as narrow gain bandwidth, poor gain performance, and high fiber noise, which urgently need to be addressed. Summary of the Invention

[0003] This invention provides an erbium-doped fiber, its preparation method, and an erbium-doped fiber amplifier, which can achieve effective gain for signals with a wider wavelength range (bandwidth), improve gain performance, reduce noise, and effectively overcome the defects of existing technologies.

[0004] In one aspect, the present invention provides an erbium-doped optical fiber, comprising a core, the core comprising a silica matrix and erbium and zirconium elements present in the silica matrix, wherein the mass percentage of the zirconium element in the core is 0.01% to 5%.

[0005] According to one embodiment of the present invention, the zirconium content in the fiber core is 0.05% to 1% by mass.

[0006] According to one embodiment of the present invention, the erbium content in the fiber core is 0.01% to 1% by mass.

[0007] According to one embodiment of the present invention, the fiber core further includes one or more of the following elements: aluminum, phosphorus, ytterbium, lanthanum, germanium, and fluorine.

[0008] According to one embodiment of the present invention, the fiber core includes aluminum, and the mass percentage of aluminum in the fiber core is 0.5% to 12%; and / or, the fiber core includes phosphorus, and the mass percentage of phosphorus in the fiber core is 0.5% to 15%; and / or, the fiber core includes ytterbium, and the mass percentage of ytterbium in the fiber core is 0.01% to 1%; and / or, the fiber core includes lanthanum, and the mass percentage of lanthanum in the fiber core is 0.01% to 1%; and / or, the fiber core includes germanium, and the mass percentage of germanium in the fiber core is 0.01% to 1%.

[0009] According to one embodiment of the present invention, the noise of the erbium-doped optical fiber is less than or equal to 7.5 dB.

[0010] According to one embodiment of the present invention, the noise of the erbium-doped optical fiber is less than or equal to 4.5 dB.

[0011] According to one embodiment of the present invention, the fiber core includes aluminum, and the mass percentage of the aluminum in the fiber core is greater than or equal to 8%; and / or, the gain of the erbium-doped fiber in the λ1-λ2 band is greater than or equal to 17dB, 1520nm≤λ1≤1530nm, and λ2-λ1≥48nm.

[0012] According to one embodiment of the present invention, the aluminum element in the fiber core has a mass percentage content of 8% to 12%; and / or, the fiber core further includes phosphorus element, and the phosphorus element in the fiber core has a mass percentage content of 0.5% to 12%.

[0013] According to one embodiment of the present invention, the fiber core includes phosphorus, and the mass percentage of phosphorus in the fiber core is greater than or equal to 10%; and / or, the gain of the erbium-doped fiber in the λ3-λ4 band is greater than or equal to 12dB, 1560nm≤λ3≤1580nm, and λ4-λ3≥52nm.

[0014] According to one embodiment of the present invention, the mass percentage of phosphorus in the fiber core is 10% to 12%.

[0015] According to one embodiment of the present invention, the erbium-doped optical fiber further includes a cladding disposed on the outside of the fiber core.

[0016] According to one embodiment of the present invention, the cladding comprises a quartz tube; and / or, the erbium-doped optical fiber further comprises a coating layer located on the side of the cladding opposite to the fiber core, the coating layer comprising an acrylic resin.

[0017] In another aspect, the present invention provides a method for preparing the above-mentioned erbium-doped optical fiber, comprising the following steps: forming a core layer in a first cladding material using a raw material for forming the fiber core, thereby obtaining a first cladding material having a core layer; subsequently, heat-treating the first cladding material having a core layer; obtaining an optical fiber preform; and drawing the optical fiber preform to obtain the erbium-doped optical fiber.

[0018] According to one embodiment of the present invention, the process of forming a core layer in a first cladding material using raw materials for forming the fiber core includes: forming the core layer in the first cladding material by means of a first chemical vapor deposition method, thereby obtaining the first cladding material with the core layer formed thereon.

[0019] According to one embodiment of the present invention, the raw materials used to form the fiber core include a first raw material, a second raw material, and a third raw material. The first raw material contains silicon and germanium, the second raw material contains a second dopant element, which includes erbium and zirconium, and the third raw material contains phosphorus. The process of forming a core layer in a first cladding material using the raw materials for forming the fiber core includes: using the first raw material, depositing a porous layer containing silicon and germanium in the first cladding material by a second chemical vapor deposition method; subsequently, using the second raw material, doping the porous layer with the second dopant element by a liquid phase doping method; and subsequently, using the third raw material, doping the porous layer with phosphorus by a third chemical vapor deposition method to obtain the first cladding material with the core layer formed thereon.

[0020] According to one embodiment of the present invention, the first cladding material comprises a quartz tube; and / or, the heat treatment process comprises: sequentially subjecting the first cladding material with the core layer to a first melting and shrinkage treatment and a sintering treatment to obtain a preform precursor; wherein the temperature of the first melting and shrinkage treatment is 2000–2500°C, and the temperature of the sintering treatment is 2000–2500°C; applying a second cladding material to the outside of the preform precursor, and then performing a second melting and shrinkage treatment at 2000–2500°C to obtain the optical fiber preform.

[0021] According to one embodiment of the present invention, the conditions for the wire drawing process are: wire drawing temperature of 2050℃-2150℃ and wire drawing speed of 60m / min-100m / min.

[0022] According to one embodiment of the present invention, the second cladding material comprises a quartz tube.

[0023] In another aspect, the present invention provides an erbium-doped fiber amplifier, comprising the above-described erbium-doped fiber or an erbium-doped fiber prepared according to the above-described method for preparing erbium-doped fiber.

[0024] The erbium-doped fiber of this invention comprises silicon, erbium, and zirconium in its core. This enhances the gain bandwidth of the erbium-doped fiber, enabling effective gain over a wider wavelength range, improving gain performance, reducing noise, and enhancing overall fiber performance. Furthermore, the erbium-doped fiber of this invention offers advantages such as simple structure and ease of mass production, facilitating practical industrial applications. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the structure of an erbium-doped optical fiber according to an embodiment of the present invention;

[0026] Figure 2This is a C-band single-stage full-wave amplification gain diagram of the erbium-doped fiber CI in Embodiment 1 of the present invention (the horizontal axis is wavelength, and the vertical axis is gain).

[0027] Figure 3 The noise diagram of a single-stage full-wave amplification in the C-band of the erbium-doped fiber CI in Embodiment 1 of the present invention is shown (the horizontal axis represents wavelength, and the vertical axis represents noise).

[0028] Figure 4 This is a single-stage full-wave gain diagram of the L-band of the erbium-doped fiber LI in Embodiment 1 of the present invention.

[0029] Figure 5 This is a noise diagram of a single-stage full-wave amplification in the L-band of the erbium-doped fiber LI according to Embodiment 1 of the present invention.

[0030] Explanation of reference numerals in the attached figures: 1: Fiber core; 2: Cladding; 3: Inner coating; 4: Outer coating. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the present invention will be further described in detail below. The specific embodiments listed below are merely descriptions of the principles and features of the present invention, and the examples are only for explaining the present invention and are not intended to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In related technologies, optical fibers generally suffer from problems such as narrow gain bandwidth, poor gain performance, and high fiber noise, which urgently need to be solved. For example, erbium-doped fiber has narrow gain bandwidth in the C-band and L-band, which cannot achieve effective gain for signals over a wide range of bands, and the gain level is low (i.e., poor gain performance). At the same time, the noise is relatively high, which limits its application.

[0033] Specifically, gain, measured in dB, refers to the difference between the optical power (in dBm) at the output and input of the optical amplifier. Noise, measured in dB, primarily originates from shot noise in the signal light, beat noise between the signal light and the amplifier's spontaneously emitted light, shot noise in the amplified spontaneously emitted light, and beat noise between different frequencies of spontaneously emitted light from the optical amplifier. Generally, the C-band ranges from 1530nm to 1565nm, representing the conventional band, while the L-band ranges from 1565nm to 1625nm, representing the second lowest loss band. When the C-band is insufficient to meet bandwidth requirements, the L-band is added for multiplexing within the same optical fiber.

[0034] According to the inventors' research, zirconium (Zr) doping can be used to extend the gain spectrum of erbium-doped optical fibers (or erbium fibers). Introducing zirconium into the fiber core, which is based on silica glass (silicon dioxide (SiO2)), can achieve a broad-spectrum gain of 1550 nm to 1590 nm. However, zirconium oxide (ZrO2) has low solubility in glass networks. During the fabrication of erbium-doped optical fibers, the formed ZrO2 often undergoes a phase transition process. For example, ZrO2 usually undergoes a phase transition process during the cooling process after heat treatment, causing Zr-doped optical fibers to easily separate and crystallize, increasing the intrinsic loss of erbium fibers and resulting in problems such as low gain and high noise.

[0035] In view of this, embodiments of the present invention provide an erbium-doped optical fiber, such as... Figure 1 As shown, the erbium-doped optical fiber includes a core 1, which comprises a silica matrix (i.e., the core 1 contains silicon (silicon ions)) and erbium (erbium ions) present in the silica matrix. 3+ )) and zirconium element (zirconium ion (Zr) 4+ The zirconium content in fiber core 1 is 0.01% to 5% by mass.

[0036] According to the inventors' research, in the aforementioned core 1 composition system, introducing zirconium into the core 1 of the erbium-doped fiber and controlling the mass percentage (doping concentration) of zirconium within the range of 0.01% to 5% can regulate the local coordination field (local coordination environment) of erbium ions in core 1, optimizing the gain performance and gain bandwidth of the erbium-doped fiber. Simultaneously, it facilitates the uniformity of zirconium doping in core 1, avoiding the formation of ZrO2 clusters due to localized uneven doping, which in turn leads to the crystallization process of tetragonal ZrO2, and the resulting... This addresses issues such as erbium fiber loss and its impact on fiber performance. Simultaneously, by controlling the zircon doping concentration within the range of 0.01% to 5%, the [SiO4] tetrahedra in the zircon (ZrSiO4) structure formed by zircon in fiber core 1 are integrated into the silica matrix (quartz glass) grid. This facilitates the dissolution of zircon crystals within the glass grid, preventing zircon crystallization and the resulting increase in erbium fiber loss. Ultimately, this improves the gain bandwidth and gain performance of the erbium-doped fiber, while reducing its noise.

[0037] Therefore, in the erbium-doped fiber of this embodiment, using a silicon dioxide matrix as the core 1 and doping it with 0.01% to 5% zirconium can optimize the local coordination field of erbium ions, reduce problems such as phase separation and crystallization of zirconium doping, reduce the fiber's inherent loss, and simultaneously improve the gain bandwidth and gain performance of the erbium-doped fiber, while also reducing the noise and improving the fiber's performance. Specifically, the inherent loss of the erbium-doped fiber can be as low as below 15dB / km (i.e., less than or equal to 15dB / km), the gain bandwidth in the C-band or L-band can be greater than or equal to 48nm, the gain (or gain value) can be greater than or equal to 12dB, and the noise can be less than or equal to 7.5dB, for example, less than or equal to 4.5dB.

[0038] For example, the mass percentage of zirconium in the fiber core 1 can be a range of 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, or any combination thereof.

[0039] Specifically, the mass percentage of zirconium in core 1 can be greater than or equal to 0.05% (i.e., the doping concentration of zirconium can be 0.05% to 5%). Under the composition system of core 1 with relatively high zirconium doping, it is more conducive to improving the gain bandwidth and gain value of erbium-doped fiber and reducing the noise of erbium-doped fiber.

[0040] In some embodiments, the zirconium content in the fiber core 1 can be 0.05% to 1% by mass, which is more conducive to balancing the improvement of the gain bandwidth and gain value of the erbium-doped fiber and the reduction of the noise of the erbium-doped fiber.

[0041] Furthermore, the mass percentage of erbium in fiber core 1 can be 0.01% to 1%, for example, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any combination thereof. The erbium doping concentration in fiber core 1 is within the above range. By controlling the doping distribution of erbium in fiber core 1, it is more conducive to compatibility with zirconium. By controlling the local coordination field of erbium ions through zirconium doping, the gain performance and gain bandwidth of erbium-doped fiber can be optimized.

[0042] In addition, the core 1 may also include other doped elements, specifically aluminum (aluminum ions (Al)). 3+ Phosphorus element (phosphine ions (P)) 5+ ), Ytterbium (ytterbium ion (Yb) 3+ )), Lanthanum (lanthanum ion (La) 3+ germanium element (germanium ion (Ge)) 4+The use of one or more of the following elements, such as fluorine, is beneficial for further improving the performance of optical fibers. These doping elements are all present in the silicon dioxide matrix, that is, doped in the fiber core 1.

[0043] Generally, the elements in erbium-doped optical fibers mainly exist in the form of metal oxides. That is, erbium-doped optical fibers include metal oxides of the above-mentioned elements. For example, erbium-doped optical fibers include one or more of erbium trioxide (Er2O3), aluminum trioxide (Al2O3), zirconium dioxide (ZrO2), ytterbium trioxide (Yb2O3), phosphorus pentoxide (P2O5), lanthanum trioxide (La2O3), and germanium dioxide (GeO2).

[0044] In some embodiments, the core 1 includes aluminum, and the mass percentage of aluminum in the core 1 can be 0.5% to 12%, for example, a range of 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, or any combination thereof.

[0045] In some embodiments, the core 1 includes phosphorus, and the mass percentage of phosphorus in the core 1 can be 0.5% to 15%, for example, a range of 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or any combination thereof.

[0046] Hereinafter, doping elements other than erbium, zirconium, aluminum and phosphorus will be referred to as doping element A. Doping element A includes, for example, one or more of the above-mentioned elements such as ytterbium, lanthanum, germanium and fluorine. That is, one or more doping elements A can be doped into the fiber core 1. For each doping element A, its mass percentage in the fiber core 1 can be 0.01% to 1%, for example, 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1% or any combination thereof.

[0047] In some embodiments, the fiber core 1 includes ytterbium, and the mass percentage of ytterbium in the fiber core 1 can be 0.01% to 1%, for example, a range consisting of 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any combination thereof.

[0048] In some embodiments, the core 1 includes lanthanum, and the mass percentage of lanthanum in the core 1 can be 0.01% to 1%, for example, a range consisting of 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any combination thereof.

[0049] In some embodiments, the fiber core 1 includes germanium, and the mass percentage of germanium in the fiber core 1 can be 0.01% to 1%, for example, a range of 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1%, or any combination thereof.

[0050] In this embodiment of the invention, the fiber end face can be tested by analytical methods such as electron probe microanalysis (EPMA analysis) to determine the composition and doping concentration of the fiber core 1.

[0051] According to further research by the inventors, the fiber core 1 can be a fiber core 1 component system with high aluminum doping and zirconium doping. The mass percentage of aluminum in the fiber core 1 can be greater than or equal to 8%, specifically 8% to 12%. Under the fiber core 1 component system with high aluminum doping and zirconium doping, it is more conducive to achieving broadband gain of erbium-doped fiber in the C-band and improving the gain value, while reducing noise.

[0052] In addition, the mass percentage of phosphorus in core 1 can be 0.5% to 12%, which is more conducive to adapting to the above-mentioned high aluminum-doped and zirconium-doped core 1 system, improving the gain bandwidth and gain value of erbium-doped fiber in the C-band, and reducing noise.

[0053] In some specific embodiments, for the above-mentioned aluminum-doped and zirconium-doped fiber core 1 component system, the doping concentration of erbium can be 0.01% to 1%, the doping concentration of aluminum can be 8% to 12%, the doping concentration of zirconium can be 0.05% to 1%, the doping concentration of ytterbium can be 0.01% to 1%, the doping concentration of phosphorus can be 0.5% to 12%, and the doping concentration of germanium can be 0.01% to 1%. Specifically, the fiber core 1 may include one or more of erbium trioxide (Er2O3), aluminum trioxide (Al2O3), zirconium dioxide (ZrO2), ytterbium trioxide (Yb2O3), phosphorus pentoxide (P2O5), and germanium dioxide (GeO2), and its component system may specifically be SiO2-Er2O3-Al2O3-ZrO2-Yb2O3-P2O5-GeO2.

[0054] In the embodiments of the present invention, unless otherwise specified, the doping concentration of a certain component refers to the mass percentage content of that component in the fiber core 1.

[0055] Specifically, the gain of erbium-doped fiber in the λ1–λ2 band can be greater than or equal to 17 dB (i.e., the gain of erbium-doped fiber for any band of signal within the λ1–λ2 band range is not less than 17 dB), 1520 nm ≤ λ1 ≤ 1530 nm, λ2 - λ1 ≥ 48 nm, meaning that the gain bandwidth of erbium-doped fiber in the C-band can be greater than or equal to 48 nm, and the gain can be greater than or equal to 17 dB. Furthermore, the noise of erbium-doped fiber in the λ1–λ2 band is less than or equal to 4.5 dB.

[0056] In some specific embodiments, the broadband gain of erbium-doped fiber in the 1524nm to 1572nm band can be greater than or equal to 17dB (i.e., λ1 = 1524nm, λ2 = 1572nm), and the noise can be less than or equal to 4.5dB.

[0057] According to further research by the inventors, the fiber core 1 can be a fiber core 1 component system with high phosphorus doping and zirconium doping. The mass percentage of phosphorus element in the fiber core 1 can be greater than or equal to 10%, specifically 10% to 12%. Under the fiber core 1 component system with high phosphorus doping and zirconium doping, it is more conducive to achieving broadband gain of erbium-doped fiber in the L-band and improving the gain value, while reducing noise.

[0058] In some specific embodiments, for the above-mentioned highly phosphorus-doped and zirconium-doped fiber core 1 component system, the doping concentration of erbium can be 0.01% to 1%, the doping concentration of aluminum can be 0.5% to 12%, the doping concentration of zirconium can be 0.05% to 1%, the doping concentration of ytterbium can be 0.01% to 1%, the doping concentration of phosphorus can be 10% to 12%, the doping concentration of lanthanum can be 0.01% to 1%, and the doping concentration of germanium can be 0.01% to 1%. The fiber core 1 may specifically include one or more of erbium trioxide (Er2O3), aluminum trioxide (Al2O3), zirconium dioxide (ZrO2), ytterbium trioxide (Yb2O3), phosphorus pentoxide (P2O5), lanthanum trioxide (La2O3), and germanium dioxide (GeO2), and its composition system may specifically be SiO2-Er2O3-Al2O3-ZrO2-Yb2O3-P2O5-La2O3-GeO2.

[0059] Specifically, the gain of erbium-doped fiber in the λ3–λ4 band can be greater than or equal to 12 dB (i.e., the gain of erbium-doped fiber for any band of signal in the λ3–λ4 band range is not less than 12 dB), 1560 nm ≤ λ3 ≤ 1580 nm, λ4 - λ3 ≥ 52 nm, that is, the gain bandwidth of erbium-doped fiber in the L band can be greater than or equal to 52 nm, and the gain can be greater than or equal to 12 dB. Furthermore, the noise of erbium-doped fiber in the λ3–λ4 band is less than or equal to 7.5 dB.

[0060] In some specific embodiments, the broadband gain of erbium-doped fiber in the 1575nm to 1627nm band can be greater than or equal to 12dB (i.e., λ3 = 1575nm, λ4 = 1627nm), and the noise can be less than or equal to 7.5dB.

[0061] In this embodiment of the invention, the gain and noise characteristics of the erbium-doped fiber can be obtained by performing a single-stage full-wavelength amplification gain performance test on the erbium-doped fiber using a 980nm pump (i.e., using a single fiber (single-stage fiber) to amplify the full-wavelength optical signal in the C-band or L-band (i.e., full-stage amplification) to measure the gain and noise characteristics of the erbium-doped fiber in the C-band or L-band). Specifically, during the test, 980nm pump light is provided to the erbium-doped fiber, thereby exciting the ground-state erbium ions to a higher energy state, causing an inversion of the energy level ion number. When the signal light passes through the erbium-doped fiber, it interacts with the erbium ions to produce stimulated emission, thereby amplifying the signal light. This embodiment of the invention can use conventional methods in the art to perform a single-stage full-wavelength amplification gain performance test on the erbium-doped fiber using a 980nm pump light to measure the gain and noise characteristics of the erbium-doped fiber in the C-band or L-band.

[0062] Under normal circumstances, such as Figure 1 As shown, the erbium-doped optical fiber also includes a cladding 2 disposed on the outside of the fiber core 1, and the cladding 2 may include a quartz tube.

[0063] Continue to refer to Figure 1 Erbium-doped optical fiber may also include a coating layer located on the side of the cladding 2 opposite to the fiber core 1, the coating layer may include a polymer, specifically an acrylic resin.

[0064] Specifically, such as Figure 1 As shown, the coating layer may include an inner coating 3 located on the side surface of the cladding 2 away from the fiber core 1, and an outer coating 4 located on the side surface of the inner coating 3 away from the fiber core 1. That is, the cladding 2, the inner coating 3, and the outer coating 4 are sequentially arranged around the outside of the fiber core 1. The inner coating 3 may include a polymer, specifically acrylic resin, and the outer coating 4 may include a polymer, specifically acrylic resin.

[0065] In this embodiment of the invention, conventional acrylic resins in the art can be used to form the coating layer, such as UV-curable acrylic resins to form the inner coating layer 3 and the outer coating layer 4, etc., and there are no particular limitations on this.

[0066] This invention also provides a method for preparing the above-mentioned erbium-doped optical fiber, comprising the following steps:

[0067] A core layer is formed in a first cladding material using raw materials for forming the fiber core, resulting in a first cladding material with a core layer.

[0068] Subsequently, the first cladding material forming the core layer is heat-treated to obtain an optical fiber preform.

[0069] Erbium-doped optical fibers are produced by drawing optical fiber preforms.

[0070] Specifically, the first cladding material may include a quartz tube.

[0071] Generally, the first cladding material is first cleaned and polished sequentially before the core layer is formed within it. Specifically, the inner wall of the first cladding material is cleaned and polished through the cleaning and polishing process. Then, the core layer is deposited on the inner surface of the first cladding material. After subsequent heat treatment and other processes, the core layer forms the core of the erbium-doped optical fiber, and the first cladding material forms the cladding of the erbium-doped optical fiber. Specifically, a thin-walled quartz tube with a wall thickness of 1.5mm to 3mm can be used as the deposition tube (i.e., the first cladding material) as the preform. It is cleaned 1 to 2 times with hydrofluoric acid. Subsequently, the quartz tube undergoes high-temperature polishing (thermal polishing). This can be achieved by flame polishing the quartz tube (or quartz deposition tube) on equipment such as an MCVD lathe at a temperature of 1800℃ to 1900℃. The polishing gas can include sulfur hexafluoride (SF6). After thermal polishing, a deposition area for the core layer is formed on the inner wall of the quartz tube.

[0072] Specifically, the raw materials used to form the fiber core may include a silicon source for forming a silicon dioxide matrix, an erbium source for providing erbium, and a zirconium source for providing zirconium.

[0073] In addition, when the fiber core also includes other doping elements, the raw materials used to form the fiber core also include raw materials for providing these doping elements. For example, the raw materials used to form the fiber core include one or more of aluminum source, phosphorus source, ytterbium source, lanthanum source, germanium source, and fluorine source, so that the formed fiber core contains the corresponding doping elements.

[0074] Specifically, the aforementioned raw materials can be compounds containing the corresponding elements, such as salts or hydrates of the corresponding elements, specifically halides (such as chlorides) or hydrates of the corresponding elements. Specifically, the silicon source can include silicon tetrachloride (SiCl4), the erbium source can include erbium chloride (ErCl3), the zirconium source can include zirconium chloride (ZrCl4), the aluminum source can include aluminum chloride (AlCl3), the phosphorus source can include phosphorus oxychloride (POCl3), the ytterbium source can include ytterbium chloride (YbCl3), the lanthanum source can include lanthanum chloride (LaCl3), and the germanium source can include germanium chloride (GeCl4).

[0075] In the above preparation process, a core layer is formed in a first cladding material using raw materials for forming the fiber core, resulting in a first cladding material with a core layer. The elements in the core layer exist in the form of their oxides, such as silicon dioxide, erbium trioxide, and zirconium oxide. This core layer is a porous and loose layer, which, after subsequent heat treatment and other processes, forms a dense fiber core.

[0076] In this embodiment of the invention, during the process of forming the core layer in the first cladding material using raw materials for forming the fiber core, a silicon source can be deposited in the first cladding material by chemical vapor deposition to form a silicon dioxide matrix. When the formed fiber core contains germanium, both a silicon source and a germanium source can be deposited in the first cladding material simultaneously to achieve germanium doping in the core layer while forming the silicon dioxide matrix.

[0077] Furthermore, for the doping of erbium and zirconium, silicon, erbium, and zirconium sources can be deposited simultaneously in the first cladding material using chemical vapor deposition (including a germanium source when the core is doped with germanium). This allows for the doping of erbium and zirconium in the core layer while forming a silicon dioxide matrix. However, this is not the only option. In other embodiments, silicon sources (including a germanium source when the core is doped with germanium) can be deposited at high temperature in the first cladding material using chemical vapor deposition, followed by liquid-phase doping to dope erbium and zirconium in the core layer.

[0078] Furthermore, for the doping of other metal dopants such as aluminum, ytterbium, and lanthanum (as described below as the second doping element), a silicon source and a raw material containing these doping elements (such as one or more of aluminum, ytterbium, and lanthanum sources; when the core is doped with germanium, the raw material also includes a germanium source) can be deposited simultaneously in the first cladding material by chemical vapor deposition. This allows the doping of the element in the core layer to be achieved while forming a silicon dioxide matrix. However, this is not the only option. In other embodiments, a silicon source or other raw material (such as a germanium source when the core is doped with germanium) can be deposited at high temperature in the first cladding material by chemical vapor deposition, and then other metal dopants such as aluminum, ytterbium, and lanthanum can be doped in the core layer by liquid phase doping.

[0079] Furthermore, phosphorus doping can be achieved by chemical vapor deposition (CVD) in the core layer. Specifically, silicon and phosphorus sources (including germanium sources when the core is doped with germanium) can be deposited simultaneously in the first cladding material using CVD to achieve phosphorus doping in the core layer while forming a silicon dioxide matrix. However, this is not the only option. In other embodiments, silicon sources (including germanium sources when the core is doped with germanium) can be deposited at high temperature in the first cladding material using CVD, followed by liquid-phase doping of erbium, zirconium, aluminum, ytterbium, and lanthanum metal dopants in the core layer. Then, phosphorus sources can be deposited using CVD to achieve phosphorus doping in the core layer.

[0080] In this embodiment of the invention, the chemical vapor deposition method can be a modified chemical vapor deposition (MCVD) method, and its specific operation steps can be conventional procedures in the art, without any particular limitation.

[0081] In general, during chemical vapor deposition (CVD), a mixed gas containing relevant raw materials is introduced into the first cladding material. At high temperatures, these raw materials are deposited in the first cladding material, forming a dense, porous layer (or porous tube). The mixed gas includes oxygen, silicon sources, and germanium sources, among other raw materials. Helium (high-purity helium) is also introduced during CVD. The number of deposited layers can range from 2 to 5.

[0082] In some embodiments, the process of forming a core layer in a first cladding material using raw materials for forming the core may include: forming the core layer in the first cladding material using a first chemical vapor deposition method to obtain a first cladding material with a core layer. That is, all raw materials for forming the core layer are simultaneously deposited using the first chemical vapor deposition method to form a core layer in the first cladding material.

[0083] For example, the core includes erbium, aluminum, zirconium, ytterbium, phosphorus, and germanium (the core composition system is, for example, SiO2-Er2O3-Al2O3-ZrO2-Yb2O3-P2O5-GeO2). Correspondingly, the raw materials used to form the core include these elements. In the first chemical vapor deposition process, the mixed gas introduced into the first cladding material may specifically include oxygen, a silicon source (such as silicon tetrachloride), a phosphorus source (such as phosphorus oxychloride), an erbium source containing an inert gas (such as erbium chloride), a ytterbium source (such as ytterbium chloride), a zirconium source (such as zirconium chloride), an aluminum source (such as aluminum chloride), and a germanium source (such as germanium chloride). This mixed gas is introduced into the first cladding material and deposited at high temperature to form the core layer. High-purity helium is introduced during the deposition process, and the number of deposition layers can be 2-5.

[0084] Specifically, the deposition temperature of the first chemical vapor deposition method can be 1600 to 2050°C (i.e., deposition is carried out at a deposition temperature of 1600 to 2050°C), for example, 1600°C, 1650°C, 1700°C, 1750°C, 1800°C, 1850°C, 1900°C, 1950°C, 2000°C, 2050°C or any combination thereof.

[0085] In some specific embodiments, the above-mentioned high aluminum-doped and zirconium-doped fiber core component system can be prepared by a first chemical vapor deposition method. The specific composition of the high aluminum-doped and zirconium-doped fiber core component system and the gain performance of the fiber core are detailed in the foregoing content and will not be repeated here.

[0086] In other embodiments, the raw materials used to form the fiber core include a first raw material, a second raw material, and a third raw material. The first raw material contains silicon and germanium (i.e., the first raw material includes a silicon source and a germanium source), the second raw material contains a second doping element, which includes erbium and zirconium (i.e., the second raw material includes erbium sources and zirconium sources, etc., containing the second doping element), and the third raw material contains phosphorus (i.e., the third raw material includes a phosphorus source). The process of forming a core layer in the first cladding material using the raw materials used to form the fiber core may include: using the first raw material, depositing a loose layer containing silicon (the loose layer includes a silicon dioxide substrate) in the first cladding material by a second chemical vapor deposition method; subsequently, using the second raw material, doping the loose layer with the second doping element by a liquid phase doping method; and subsequently, using the third raw material, doping the loose layer with phosphorus by a third chemical vapor deposition method to obtain a first cladding material with a core layer formed thereon. In contrast, doping zirconium into the fiber core via liquid-phase doping facilitates further control over the uniformity of zirconium doping, avoiding the formation of ZrO2 agglomeration due to localized uneven doping, which leads to the crystallization process of tetragonal ZrO2. This further reduces erbium fiber loss and improves fiber performance.

[0087] In this embodiment of the invention, the doping element in the first raw material is referred to as the first doping element, the doping element in the second raw material is referred to as the second doping element, and the doping element in the third raw material is referred to as the third doping element. The first doping element and the second doping element are different. For example, in the first raw material, the first doping element other than silicon is germanium, and the third doping element in the third raw material is phosphorus. However, the second doping element in the second raw material does not contain silicon, germanium, or phosphorus. That is, the second doping element in the second raw material is a doping element other than the first doping element and the third doping element.

[0088] In some embodiments, the second doping element in the second raw material may further include one or more of aluminum, ytterbium, and lanthanum, that is, the second raw material includes one or more of aluminum source, ytterbium source, and lanthanum source.

[0089] Specifically, the first raw material is a mixed gas, which may include a silicon source containing oxygen (such as silicon tetrachloride) and a germanium source containing an inert gas (such as germanium chloride). During the deposition process of the second chemical vapor deposition method, the first raw material is introduced into the first cladding material and deposited at high temperature to form a dense and porous loose layer. Each raw material forms a corresponding metal oxide, thereby forming a silicon dioxide matrix doped with germanium (i.e., a loose layer or SiO2-GeO2 loose tube) in the first cladding material, resulting in a first cladding material with a loose layer. High-purity helium gas is introduced during the deposition process, and the number of deposition layers can be 2-5.

[0090] Specifically, the deposition temperature of the second chemical vapor deposition method can be 1350℃ to 1600℃ (i.e., at which a loose layer is deposited in the first cladding material by the second vapor deposition method), for example, 1350℃, 1400℃, 1450℃, 1500℃, 1550℃, 1600℃ or any combination thereof.

[0091] Specifically, the process of doping a second dopant element into a porous layer using a liquid-phase doping method with a second raw material may include: immersing the first cladding material with the porous layer formed thereon into a liquid-phase doping solution containing the second raw material for 30 to 60 minutes, followed by drying (specifically, drying can be achieved by introducing gases such as oxygen (O2) and / or chlorine (Cl2) into the porous tube at low temperature), thereby achieving doping of the second dopant element into the hydrophobic layer. The liquid-phase doping solution (or liquid-phase doping solution) is a mixture of the second raw material (solute) and a solvent. The solvent may include one or more of water, methanol, ethanol, etc., i.e., the solvent may be one of these solvents or a mixture of multiple solvents. The water used may specifically be deionized water.

[0092] In addition, the third raw material is a mixed gas, which may specifically include a phosphorus source containing oxygen (such as phosphorus oxychloride). During the deposition process of the third chemical vapor deposition method, the third raw material is introduced into a loose layer doped with the second dopant element, and deposited at high temperature to form a core layer, with each raw material forming a corresponding metal oxide. High-purity helium gas is introduced during the deposition process.

[0093] Specifically, the deposition temperature of the third chemical vapor deposition method can be 1100℃ to 1300℃, for example, 1100℃, 1150℃, 1200℃, 1550℃, 1300℃ or any combination thereof.

[0094] In some specific embodiments, the above-mentioned highly phosphorus-doped and zirconium-doped fiber core component system can be prepared by a preparation process including the second chemical vapor deposition method, the liquid phase doping method and the third vapor deposition method. The specific composition of the highly phosphorus-doped and zirconium-doped fiber core component system and the gain performance of the fiber core are detailed in the foregoing content and will not be repeated here.

[0095] In the above-mentioned erbium-doped optical fiber preparation process, after depositing the core layer in the first cladding material, the first cladding material with the core layer is subjected to heat treatment. The heat treatment process may include: sequentially performing a first fusion shrinkage treatment and a sintering treatment on the first cladding material with the core layer to obtain a preform precursor; applying a second cladding material to the outside of the preform precursor, and then performing a second fusion shrinkage treatment at 2000-2500℃ to obtain an optical fiber preform.

[0096] In the above preparation process, the first cladding material with the core layer is shrunk into a core rod by a first shrinking treatment, which is then shrunk at a high temperature to form the core rod of the optical fiber preform. The temperature of the first shrinking treatment can be between 2000 and 2500°C, for example, 2000°C, 2100°C, 2200°C, 2300°C, 2400°C, 2500°C, or any combination thereof. The duration of the first shrinking treatment can be between 20 and 40 minutes, for example, 30 minutes. In practice, the first cladding material with the core layer can be subjected to the first shrinking treatment at the aforementioned temperature (2000–2500°C).

[0097] Furthermore, during the aforementioned preparation process, sintering treatment makes the mandrel structure more compact, forming a fiber core. Specifically, the sintering temperature can be 2000–2500℃, for example, 2000℃, 2100℃, 2200℃, 2300℃, 2400℃, 2500℃, or any combination thereof, and the sintering time can be 0.5–1.5 hours, for example, 1 hour. In practice, a flame torch can be used to repeatedly heat the mandrel formed after the first melting and shrinking treatment at high temperatures to sinter it at a preset temperature for a preset time.

[0098] Furthermore, after sintering, the preform precursor obtained according to the preset core-cladding ratio is clad, that is, a second cladding material is clad on the outside of the preform precursor, and then melted and shrunk at 2000-2500℃ to form an optical fiber preform (i.e., a second melting and shrunk treatment is performed at 2000-2500℃ to obtain the optical fiber preform). The temperature of the second melting and shrunk treatment is, for example, 2000℃, 2100℃, 2200℃, 2300℃, 2400℃, 2500℃ or any combination thereof, and the time of the second melting and shrunk treatment can be 1.5-2.5 hours, for example, 2 hours. After the second melting and shrunk treatment, the second cladding material forms the cladding of the erbium-doped optical fiber.

[0099] Subsequently, the optical fiber preform can be polished, specifically by flame polishing at a temperature of 1800℃~1800℃. To facilitate the polishing process, a handle can be attached to the optical fiber preform before flame polishing. After polishing, the handle can be removed to obtain the polished optical fiber preform.

[0100] Subsequently, the polished optical fiber preform is drawn into fibers at a high temperature. The drawing conditions can be as follows: the drawing temperature can be 2050℃-2150℃, such as 2050℃, 2100℃ or 2150℃, and the drawing speed can be 60m / min-100m / min, such as 60m / min, 70m / min, 80m / min, 90m / min or 100m / min.

[0101] Specifically, the second cladding material can be the same as the first cladding material, and the second cladding material may specifically include a quartz tube.

[0102] In addition, during the above preparation process, after the optical fiber preform is drawn into fibers, a protective material such as resin is coated on the surface of the formed fiber to form a coating layer. Specifically, an inner coating layer and an outer coating layer (or outer cladding layer) can be coated in sequence to obtain erbium-doped optical fiber.

[0103] Through the above-described preparation process, this invention can improve the doping uniformity of zirconium in the core of the erbium-doped fiber, reduce the phase separation and crystallization problems of zirconium in the core, and simultaneously control the doping concentration, doping distribution, and local coordination field of erbium ions and other elements in the core, thereby optimizing the gain performance and gain bandwidth of the erbium-doped fiber. Specifically, it can improve the gain bandwidth and gain value of the erbium-doped fiber in both the C-band and L-band, and reduce noise. It also has the advantages of simple structure and easy mass production, which is beneficial for practical industrial applications.

[0104] In the embodiments of the present invention, unless otherwise specified, the chemical vapor deposition, melting and shrinking, sintering, rod forming, flame polishing, coating and other processes involved can all be conventional operations in the art. The temperature and other conditions of chemical vapor deposition, melting and shrinking, sintering, flame polishing and other processes can be adjusted by conventional processes in the art so that each process is carried out under preset temperature and other conditions.

[0105] This invention also provides an erbium-doped fiber amplifier, comprising the above-mentioned erbium-doped fiber or erbium-doped fiber prepared according to the above-mentioned method for preparing erbium-doped fiber. The erbium-doped fiber amplifier has advantages corresponding to the above-mentioned erbium-doped fiber, which will not be described in detail here.

[0106] Specifically, the erbium-doped fiber in the embodiments of the present invention can be used as a transmission fiber, which is the core component of the erbium-doped fiber amplifier. Specifically, it can be used in C-band broadband gain EDFA optical amplifier devices, L-band broadband gain EDFA optical amplifier devices, etc. That is, the fiber amplifier in the embodiments of the present invention can be a C-band broadband gain EDFA optical amplifier device, an L-band broadband gain EDFA optical amplifier device, etc.

[0107] The present invention will be further described below through specific embodiments.

[0108] Example 1

[0109] The structural schematic diagram of the erbium-doped fiber in Embodiment 1 is shown below. Figure 1 As shown, the fiber core composition system is SiO2-Er2O3-Al2O3-ZrO2-Yb2O3-P2O5-GeO2, wherein Er... 3+ The doping concentration is 0.01wt% to 1wt%, Al 3+ The doping concentration of Zr is 8wt% to 12wt%. 4+ The doping concentration is 0.05wt% to 1wt%, Yb 3+ The doping concentration is 0.01wt% to 1wt%, P 5+ The doping concentration is 0.5wt% to 12wt%, Ge 4+ The doping concentration is 0.01wt% to 1wt%.

[0110] The fabrication process of the erbium-doped optical fiber in Example 1 is as follows:

[0111] Step 1-1: Quartz tube cleaning; Thin-walled quartz tubes (first cladding material) are used as the deposition tubes for the preform rods, with a wall thickness of 1.5mm to 3mm, and are cleaned with hydrofluoric acid 1-2 times.

[0112] Steps 1-2: High-temperature polishing of quartz tubes: The quartz deposition tubes are flame polished on an MCVD lathe at a temperature of 1800℃~1900℃ and the polishing gas is sulfur hexafluoride.

[0113] Steps 1-3: High-temperature vapor deposition of the core layer (first chemical vapor deposition method): A mixed gas including SiCl4 and POCl3 containing oxygen, and ErCl3, YbCl3, ZrCl4, AlCl3, and GeCl4 containing inert gases is introduced into a polished quartz tube, and a core layer is formed by deposition at high temperature; high-purity helium is introduced during the deposition process, the deposition temperature is 1600℃-2050℃, and the number of deposition layers is 2-5.

[0114] Steps 1-4, Core shrinking (first melting and shrinking process): The quartz tube with the core layer is melted and shrunk at high temperature into the core rod of the optical fiber preform.

[0115] Steps 1-5, Sintering treatment: The mandrel is heated to a high temperature using a flame torch to sinter it.

[0116] Steps 1-6, cladding and polishing: The core rod (preform precursor) obtained in step 1-5 is clad with a quartz tube (second cladding material), and shrunk at high temperature to form an optical fiber preform (i.e., the second shrunk process). The handle is connected and flame polished at a temperature of 1800℃~1900℃ to obtain the polished optical fiber preform.

[0117] Steps 1-7, drawing and coating: The polished optical fiber preform is melted and drawn into fibers at high temperature (i.e., drawing process), with a drawing temperature of 2050℃-2150℃ and a drawing speed of 60m / min-100m / min; an inner coating and an outer coating are sequentially coated on the surface of the formed fiber to obtain erbium-doped optical fiber, wherein both the inner coating and the outer coating are made of UV-cured acrylic resin.

[0118] In Example 1, the erbium-doped fiber was tested for single-stage full-wave amplification gain performance by 980nm pumping (i.e., applying 980nm pump light to the erbium-doped fiber and testing its amplification gain). The test results showed that it can achieve broadband gain in the C-band. Specifically, the gain of the erbium-doped fiber in the λ1-λ2 band is greater than or equal to 17dB (i.e., the gain of the erbium-doped fiber for any band signal in the λ1-λ2 band range is not less than 17dB), 1520nm≤λ1≤1530nm, λ2-λ1≥48nm, and the noise of the erbium-doped fiber is not higher than 4.5dB.

[0119] To further illustrate, referring to the preparation process of Example 1 above, an erbium-doped fiber CI with the following core composition was obtained: the core composition system of the erbium-doped fiber CI is SiO2-Er2O3-Al2O3-ZrO2-Yb2O3-P2O5-GeO2, wherein Er... 3+ The doping concentration is approximately 0.5 wt%, Al 3+ The doping concentration is approximately 10 wt%, Zr4+ The doping concentration is approximately 0.6 wt%, Yb 3+ The doping concentration is approximately 0.5 wt%, P 5+ The doping concentration is approximately 5 wt%, Ge 4+ The doping concentration is approximately 0.05 wt%. In the fabrication process of this erbium-doped optical fiber (CI), in step 1-1, the thickness of the thin-walled quartz tube is approximately 2.3 mm; in step 1-3, the deposition temperature is approximately 1850℃, and the number of deposition layers is 3; in step 1-4, the temperature of the first melting and shrinking treatment is approximately 2300℃, and the time is approximately 0.5 h; in step 1-5, the sintering treatment temperature is approximately 2300℃, and the time is approximately 1 h; in step 1-6, the temperature of the second melting and shrinking treatment is approximately 2300℃, and the time is approximately 2 h; in step 1-7, the drawing temperature is approximately 2000℃, and the drawing speed is approximately 80 m / min.

[0120] The single-stage full-wave amplification gain performance of erbium-doped fiber CI was tested by pumping at 980 nm. The measured single-stage full-wave amplification gain diagram of erbium-doped fiber CI is shown in the figure. Figure 2 See the single-stage full-wave amplification noise diagram. Figure 3 ,from Figure 2 and Figure 3 As can be seen, erbium-doped fiber CI can achieve a wide-spectrum gain of 1524nm-1572nm, with a gain bandwidth of ≥48nm in the C-band, a gain of ≥17dB, and noise of ≤4.5dB.

[0121] Example 2

[0122] The structural schematic diagram of the erbium-doped fiber in this embodiment 2 is shown below. Figure 1 As shown, the fiber core composition system is SiO2-Er2O3-Al2O3-ZrO2-Yb2O3-P2O5-La2O3-GeO2, wherein Er... 3+ The doping concentration is 0.01-1 wt%, Al 3+ The doping concentration is 0.5-12 wt%, Zr 4+ The doping concentration is 0.05-1 wt%, Yb 3+ The doping concentration is 0.01-1 wt%, P 5+ The doping concentration is 10-12 wt%, La 3+ The doping concentration is 0.01-1 wt%, Ge 4+ The doping concentration is 0.01-1 wt%.

[0123] The fabrication process of the erbium-doped optical fiber in Example 2 is as follows:

[0124] Step 2-1, Quartz tube cleaning; Thin-walled quartz tubes (first cladding material) are used as the deposition tubes for the preform, with a wall thickness of 1.5mm to 3mm, and are cleaned with hydrofluoric acid 1-2 times.

[0125] Step 2-2, High-temperature polishing of quartz tube: The quartz deposition tube is flame polished on an MCVD lathe at a temperature of 1800℃~1900℃ and the polishing gas is sulfur hexafluoride.

[0126] Steps 2-3, Deposition of the porous layer (second chemical vapor deposition method): A mixed gas including SiCl4 containing oxygen and GeCl4 containing inert gas is introduced into a polished quartz tube, and a dense and porous SiO2-GeO2 porous tube (i.e., porous layer) is deposited at high temperature; high-purity helium gas is introduced during the deposition process, the deposition temperature is 1350℃-1600℃, and the number of deposition layers is 2-5.

[0127] Step 2-4, Liquid phase doping: Immerse the porous tube obtained in step 2-3 in the liquid phase doping solution for 30-60 minutes, and then dry it by passing O2 or Cl2 through the tube at low temperature; wherein the solvent of the liquid phase doping solution is deionized water, methanol, ethanol liquid or a mixture thereof, and the solute is AlCl3, ZrCl4, ErCl3, YbCl3, LaCl3 salt or hydrate thereof;

[0128] Steps 2-5: High-temperature vapor deposition (i.e., third chemical vapor deposition) to form the core layer: A mixed gas including POCl3 containing oxygen is introduced into the porous tube obtained in step 2-4, and the core layer is formed by deposition at high temperature; wherein, high-purity helium is introduced during the porous layer doping deposition process, and the deposition temperature is 1100℃-1300℃.

[0129] Steps 2-6, Core shrinking (first melting and shrinking process): The quartz tube with the core layer is melted and shrunk at high temperature into the core rod of the optical fiber preform.

[0130] Steps 2-7, Sintering treatment: The mandrel is heated to a high temperature using a flame torch to sinter it.

[0131] Steps 2-8, cladding and polishing: The core rod (preform precursor) obtained in step 5 is clad with a quartz tube (second cladding material), and shrunk at high temperature to form an optical fiber preform (i.e., the second shrunk process). The handle is connected and flame polished at a temperature of 1800℃~1900℃ to obtain the polished optical fiber preform.

[0132] Steps 2-9: Fiber Drawing and Coating: The polished optical fiber preform is melted and drawn into fibers at a high temperature (i.e., fiber drawing). The drawing temperature is 2050℃-2150℃ and the drawing speed is 60m / min-100m / min. An inner coating and an outer coating are sequentially coated on the surface of the formed fiber to obtain erbium-doped optical fiber. Both the inner and outer coatings are made of UV-cured acrylic resin.

[0133] In Example 2, the erbium-doped fiber was tested for single-stage full-wave amplification gain performance using a 980nm pump. The test results showed that it can achieve broadband gain in the L-band. Specifically, the gain of the erbium-doped fiber in the λ3-λ4 band is greater than or equal to 12dB (i.e., the gain of the erbium-doped fiber for any band signal in the λ3-λ4 band range is not less than 12dB), 1560nm≤λ3≤1580nm, λ4-λ3≥52nm, and the noise of the erbium-doped fiber is not higher than 7.5dB.

[0134] To further illustrate, referring to the preparation process of Example 2 above, an erbium-doped fiber LI with the following core composition was obtained: the core composition system of the erbium-doped fiber LI is SiO2-Er2O3-Al2O3-ZrO2-Yb2O3-P2O5-La2O3-GeO2, wherein Er... 3+ The doping concentration is approximately 0.5 wt%, Al 3+ The doping concentration of Zr is approximately 5 wt%. 4+ The doping concentration is approximately 0.6 wt%, Yb 3+ The doping concentration is approximately 0.5 wt%, P 5+ The doping concentration is approximately 11 wt%, La 3+ The doping concentration is approximately 0.5 wt%, Ge 4+ The doping concentration is approximately 0.5 wt%. In the fabrication process of this erbium-doped optical fiber (LI), in step 2-1, the thickness of the thin-walled quartz tube is approximately 2.3 mm; in step 2-3, the deposition temperature is approximately 1500℃, and the number of deposition layers is 3; in step 2-4, the soaking time is approximately 45 min; in step 2-5, the deposition temperature is 1200℃; in step 2-6, the first melting and shrinking treatment temperature is approximately 2300℃, and the time is approximately 0.5 h; in step 2-7, the sintering treatment temperature is approximately 2300℃, and the time is approximately 1 h; in step 2-8, the second melting and shrinking treatment temperature is approximately 2300℃, and the time is approximately 2 h; in step 2-9, the drawing temperature is approximately 2000℃, and the drawing speed is approximately 80 m / min.

[0135] The single-stage full-wave gain performance of erbium-doped fiber LI was tested by pumping at 980 nm. The measured single-stage full-wave gain of erbium-doped fiber LI is shown in the figure. Figure 4 See the single-stage full-wave amplification noise diagram. Figure 5 ,from Figure 4 and Figure 5 As can be seen, erbium-doped fiber LI can achieve a wide-spectrum gain in the range of 1575nm-1627nm, with a gain bandwidth of ≥52nm, a gain of ≥12dB, and noise of ≤7.5dB in the L band.

[0136] Furthermore, research shows that, based on the scheme of Example 1, when the zirconium doping concentration in the fiber core is too low (<0.01%) or too high (>5%), it is impossible to simultaneously improve the gain and reduce the noise of the erbium-doped fiber. Similarly, based on the scheme of Example 2, when the zirconium doping concentration in the fiber core is too low (<0.01%) or too high (>5%), it is also impossible to simultaneously improve the gain and reduce the noise of the erbium-doped fiber. The reason for this is that zirconium doping in the fiber core affects the local coordination environment of erbium ions, thereby affecting the stimulated emission effect of erbium ions. At the same time, the zirconium doping concentration, in addition to affecting the local coordination environment of erbium ions, also affects the uniformity of zirconium distribution in the fiber core and the dissolution of the resulting zircon crystals in the glass network. These factors all affect the gain bandwidth, gain performance, and noise generation of the erbium-doped fiber. Therefore, by introducing zirconium into erbium-doped optical fibers based on silica and controlling the zirconium doping concentration within the range of 0.01% to 5%, the local coordination environment of erbium ions can be optimized, while maintaining the uniformity of zirconium distribution in the fiber core, reducing zirconium doping phase separation and crystallization problems, and reducing fiber background loss. This achieves the goal of improving the gain bandwidth and gain performance of erbium-doped optical fibers, reducing noise, and improving fiber performance.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An erbium-doped optical fiber, characterized in that, The fiber core includes a silicon dioxide matrix and erbium and zirconium elements present in the silicon dioxide matrix, wherein the zirconium element in the fiber core has a mass percentage content of 0.01% to 5%.

2. The erbium-doped optical fiber according to claim 1, characterized in that, The zirconium content in the fiber core is 0.05% to 1% by mass.

3. The erbium-doped optical fiber according to claim 1, characterized in that, The erbium content in the fiber core is 0.01% to 1% by mass.

4. The erbium-doped optical fiber according to claim 1, characterized in that, The fiber core also includes one or more of the following elements: aluminum, phosphorus, ytterbium, lanthanum, germanium, and fluorine.

5. The erbium-doped optical fiber according to claim 4, characterized in that, The fiber core includes aluminum, and the mass percentage of aluminum in the fiber core is 0.5% to 12%. And / or, the fiber core includes phosphorus, and the mass percentage of phosphorus in the fiber core is 0.5% to 15%; And / or, the fiber core includes ytterbium, and the mass percentage of ytterbium in the fiber core is 0.01% to 1%; And / or, the fiber core includes lanthanum, and the mass percentage of lanthanum in the fiber core is 0.01% to 1%; And / or, the fiber core includes germanium, and the mass percentage of the germanium in the fiber core is 0.01% to 1%.

6. The erbium-doped optical fiber according to claim 1, characterized in that, The noise of the erbium-doped optical fiber is less than or equal to 7.5 dB.

7. The erbium-doped optical fiber according to claim 6, characterized in that, The noise of the erbium-doped optical fiber is less than or equal to 4.5 dB.

8. The erbium-doped optical fiber according to any one of claims 1-7, characterized in that, The fiber core includes aluminum, and the mass percentage of aluminum in the fiber core is greater than or equal to 8%. And / or, the erbium-doped fiber has a gain greater than or equal to 17dB in the λ1 to λ2 band, 1520nm≤λ1≤1530nm, and λ2-λ1≥48nm.

9. The erbium-doped optical fiber according to claim 8, characterized in that, The mass percentage of aluminum in the fiber core is 8% to 12%; And / or, the fiber core further includes phosphorus, and the mass percentage of phosphorus in the fiber core is 0.5% to 12%.

10. The erbium-doped optical fiber according to any one of claims 1-7, characterized in that, The fiber core includes phosphorus, and the mass percentage of phosphorus in the fiber core is greater than or equal to 10%. And / or, the gain of the erbium-doped fiber in the λ3 to λ4 band is greater than or equal to 12dB, 1560nm≤λ3≤1580nm, and λ4-λ3≥52nm.

11. The erbium-doped optical fiber according to claim 10, characterized in that, The phosphorus content in the fiber core is 10% to 12% by mass.

12. The erbium-doped optical fiber according to any one of claims 1-7, characterized in that, The erbium-doped optical fiber also includes a cladding disposed on the outside of the fiber core.

13. The erbium-doped optical fiber according to claim 12, characterized in that, The cladding includes a quartz tube; And / or, the erbium-doped fiber further includes a coating layer located on the side of the cladding opposite to the fiber core, the coating layer comprising an acrylic resin.

14. A method for preparing erbium-doped optical fiber according to any one of claims 1-13, characterized in that, Includes the following steps: A core layer is formed in a first cladding material using raw materials for forming the fiber core, thereby obtaining a first cladding material with a core layer. Subsequently, the first cladding material with the core layer formed is heat-treated to obtain an optical fiber preform. The optical fiber preform is drawn into fibers to obtain the erbium-doped optical fiber.

15. The erbium-doped optical fiber according to claim 14, characterized in that, The process of forming a core layer in a first cladding material using the raw material for forming the fiber core includes: forming the core layer in the first cladding material using a first chemical vapor deposition method to obtain the first cladding material with the core layer formed.

16. The erbium-doped optical fiber according to claim 14, characterized in that, The raw materials used to form the fiber core include a first raw material, a second raw material, and a third raw material. The first raw material contains silicon and germanium, the second raw material contains a second doping element, which includes erbium and zirconium, and the third raw material contains phosphorus. The process of forming the core layer in the first cladding material using the raw materials used to form the fiber core includes: Using the first raw material, a loose layer containing the silicon and germanium elements is deposited in the first cladding material by a second chemical vapor deposition method; Subsequently, the second raw material is used to dope the loose layer with the second doping element by liquid phase doping method; Subsequently, using the third raw material, the phosphorus element is doped into the porous layer by a third chemical vapor deposition method to obtain the first cladding material with a core layer.

17. The method for preparing erbium-doped optical fiber according to any one of claims 14-16, characterized in that, The first cladding material includes a quartz tube; And / or, the heat treatment process includes: sequentially subjecting the first cladding material with the core layer to a first melting and shrinkage treatment and a sintering treatment to obtain a preform precursor; wherein, the temperature of the first melting and shrinkage treatment is 2000-2500℃, and the temperature of the sintering treatment is 2000-2500℃; A second cladding material is applied to the outside of the preform, and then a second melting and shrinking process is performed at 2000-2500°C to obtain the optical fiber preform.

18. The method for preparing erbium-doped optical fiber according to claim 17, characterized in that, The second cladding material includes a quartz tube.

19. The method for preparing erbium-doped optical fiber according to any one of claims 14-16, characterized in that, The conditions for the wire drawing process are: wire drawing temperature of 2050℃-2150℃ and wire drawing speed of 60m / min-100m / min.

20. An erbium-doped fiber amplifier, characterized in that, This includes erbium-doped optical fibers as described in any one of claims 1-13, or erbium-doped optical fibers prepared according to the method described in any one of claims 14-19.

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