A broadband Er 3+ -doped multi-component germanate glass optical fiber and its application

Abstract

The invention discloses a broadband Er 3+ Doped multi-component germanate glass optical fiber and its application. 3+ The core of the multi-component germanate glass fiber is Er 3+ Doped multicomponent germanate glasses with broadband Er 3+ The cladding of the doped multi-component germanate glass optical fiber is quartz glass or multi-component oxide glass. 3+ The amplified spontaneous emission (ASE) spectrum of the doped multi-component germanate glass optical fiber covers 1450-1700 nm, and its 3 dB bandwidth can reach 80-115 nm. 3+ Doped multi-component germanate glass fiber has a wide gain bandwidth and can be used to prepare 1.5μm-band broadband optical amplifiers and broadband tunable fiber lasers.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical fibers, and particularly relates to a broadband Er 3+ -doped multi-component germanate glass optical fiber and its application. Background Art

[0002] With the full commercialization of the fifth-generation communication technology, the demand for high-capacity and high-speed optical fiber communication networks is increasing continuously. As an important part of modern optical fiber communication networks, the gain bandwidth of optical fiber amplifiers is an important factor affecting communication capacity. Although transition metal ions (such as Cr 4+ and Ni 2+ ) and the main group metal element Bi have broadband luminescence characteristics in the optical communication band, their luminescence is greatly affected by the surrounding crystal field environment, and the doping concentration is extremely low. The luminescence in glass optical fibers is very weak, the energy level lifetime is short, and the noise figure is high, so they cannot be practically applied in the field of modern optical communication yet.

[0003] Rare earth ion-doped glass optical fibers can overcome the defects of transition metal ion-doped and main group metal element-doped glass optical fibers, and have received extensive attention and research from researchers in related fields. In the specific 1.5-μm communication window band, the bandwidth of Er 3+ -doped silica optical fiber is limited (~35 nm), and with the increasing demand for modern optical fiber communication, this problem is becoming increasingly severe. In the past two or three decades, researchers have continuously tried to develop new types of broadband gain optical fibers that meet the requirements of optical network signal amplification, especially hoping to achieve optical network signal amplification in the C+L band (1530-1625 nm) on a single optical fiber, increase the optical communication capacity, and reduce the operating cost. When developing a new type of broadband gain optical fiber, it is usually necessary to start from bulk glass, obtain broadband luminescence in rare earth ion-doped glass, and then prepare it into an optical fiber. Although some studies have obtained broadband luminescence in Er 3+ -doped glass, such as Q. Qian et al. obtained 1.5-μm band luminescence with a bandwidth of 90 nm in Er 3+ -doped antimony-borosilicate glass (Qian Q, Zhao C, Yang GF, et al. Thermal stability and spectroscopic properties of Er 3+ -doped antimony-borosilicate glasses[J]. Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2008, 71(1): 280-285.), R. F. Wang et al. also obtained broadband luminescence in Er 3+Erbium-doped germanate glasses have achieved luminescence in the 1.5 μm band with a maximum bandwidth of 81 nm (Wang R, Zhou D, Zhao Z, et al. Effect of optical basicity on broadband infrared fluorescence in erbium-doped germanate glasses [J]. Journal of alloys and compounds, 2012, 513: 339-342.), but are limited by the stringent requirements of optical fiber preparation. For example, crystallization and element diffusion during the drawing process will significantly reduce the luminescence performance of the optical fiber, including luminescence efficiency and gain bandwidth. Most studies are limited to Er 3+ There are currently limited reports on the successful drawing of doped bulk glass into optical fibers, which leads to 3+ The bandwidth of doped glass fiber in the 1.5μm band is relatively narrow (<80nm). DLYang prepared erbium-ytterbium co-doped germanium tellurite glass fiber with a FWHM of 72nm (35th Australian Conference on Optical Fibre Technology.IEEE,2010:1-3). Our research group also prepared Er 3+ Doped tellurite glass fiber, obtained ASE spectrum with 3dB bandwidth of 60~80nm [Chen Dongdan. Research on basic issues of rare earth doped tellurite glass and optical fiber application [D]. Guangzhou: South China University of Technology, 2010]. Recently, Y. Xie et al. reported a quartz cladding and Er core 3+ The composite optical fiber doped with silicate glass has a bandwidth of about 55nm in the 1.5μm band (XieY, CongZ, ZhaoZ, et al. Preparation of Er:YAG crystal-derived all-glass silica fibers for a1550-nm single-frequency laser [J]. Journal of Lightwave Technology, 2021, 39 (14): 4769-4775.), which is still difficult to meet the needs of modern optical fiber communications, especially in the L band. In addition, the researchers proposed to use Er 3+ / Tm 3+ Co-doping can obtain a wide near-infrared emission bandwidth, but due to the inherent transition characteristics of rare earth ions, their energy levels are relatively close, and there will be unnecessary energy transfer and non-radiative transitions between different rare earth ions, which hinders the Er 3+ / Tm 3+ The development of co-doped glass optical fiber cannot achieve broadband luminescence in the 1.5μm band.3+ The gain bandwidth of the doped glass fiber in the 1.5-μm band enables multiplexing and demultiplexing of more wave numbers, thereby enabling transmission of more optical signals, meeting the growing demands for high-capacity and high-speed optical communication, and also meeting the requirements of broadband tunable fiber lasers, which will have important application value. Summary of the Invention

[0004] The present invention aims to solve the technical problem that existing rare-earth doped glass fibers are difficult to achieve ultra-wideband luminescence in the 1.5-μm band, and aims to provide a broadband Er 3+ -doped multi-component germanate glass fiber and its application. The ASE spectrum of the broadband Er 3+ -doped multi-component germanate glass fiber covers 1450-1700 nm, and its 3-dB bandwidth can reach 80-115 nm. Based on this fiber, broadband optical amplification and broadband tunable laser output in the 1.5-μm band can be achieved.

[0005] The object of the present invention is achieved by the following technical solutions:

[0006] The present invention provides a broadband Er 3+ -doped multi-component germanate glass fiber, the core of the fiber is Er 3+ -doped multi-component germanate glass, and the cladding of the fiber is silica glass or multi-component oxide glass.

[0007] Further, the ASE spectrum of the broadband Er 3+ -doped multi-component germanate glass fiber covers 1450-1700 nm.

[0008] Further, the 3-dB bandwidth of the ASE spectrum of the broadband Er 3+ -doped multi-component germanate glass fiber is 80-115 nm.

[0009] Further, the broadband Er 3+ -doped multi-component germanate glass fiber is a single-mode fiber.

[0010] Further, the diameter of the core of the broadband Er 3+ -doped multi-component germanate glass fiber is 4-12 μm, and the diameter of the cladding of the broadband Er 3+ -doped multi-component germanate glass fiber is 122-128 μm.

[0011] Further, the multi-component oxide glass is selected from two or more of multi-component silicate glass, multi-component germanate glass, and multi-component germanosilicate glass. Different oxide glasses can adjust the refractive index and drawing performance, and thus prepare gain fibers with different structures.

[0012] Furthermore, the cladding is a fully solid structure or contains a periodic microporous structure, which can further regulate the performance of the optical fiber (including mode field, nonlinearity, dispersion flattening, birefringence, pump absorption efficiency, etc.), and can fabricate a large-mode-field single-mode optical fiber to achieve high-power single-mode laser output.

[0013] Furthermore, the micropore diameter of the structure containing periodic micropores is 2-3 nm.

[0014] Furthermore, the micropore diameter of the structure containing periodic micropores is 3 nm.

[0015] Furthermore, the surface of the cladding has a polymer coating layer.

[0016] Furthermore, the 3+ Er-doped multicomponent germanate glass is prepared by the high-temperature melting-annealing method, and the broadband Er-doped multicomponent germanate glass optical fiber is prepared by the thermal drawing method, where the thermal drawing method includes the tube-in-tube method and the core melting method, that is, the broadband Er-doped multicomponent germanate glass optical fiber can be prepared by a commercial optical fiber drawing tower to achieve large-scale and low-cost preparation. 3+ Er-doped multicomponent germanate glass optical fiber is prepared by the tube-in-tube method. 3+ The present invention provides the application of the broadband Er-doped multicomponent germanate glass optical fiber in the preparation of a 1.5-μm band optical amplifier.

[0017] Furthermore, the 3+ Er-doped multicomponent germanate glass optical fiber is prepared by the tube-in-tube method.

[0018] The present invention provides the 3+ application of the broadband Er-doped multicomponent germanate glass optical fiber in the preparation of a 1.5-μm band optical amplifier.

[0019] The present invention also provides the 3+ application of the broadband Er-doped multicomponent oxide glass optical fiber in the preparation of a 1.5-μm band laser generating element.

[0020] Furthermore, the 3+ Er-doped multicomponent germanate glass optical fiber can be used to prepare a 1.5-μm band optical fiber amplifier and a 1.5-μm band laser generating element, and can achieve 1.5-μm band tunable laser, single-frequency laser and mode-locked laser output, and further be applied to fields such as optical communication, medical treatment, imaging, lidar, sensing, material processing, and mid-infrared laser.

[0021] Through creative exploration and research, the present invention finds that the luminescence of rare earth ions is closely related to the microstructure units of the glass, and different matrix glasses have different microstructure units, which have a certain influence on the luminescence peak position and bandwidth of rare earth ions, such as causing the luminescence peak position to shift blue or red, and broadening the luminescence spectrum, etc. To achieve Er 3+One way of broadband luminescence is to adjust the coordination environment of rare-earth ions, causing the upper and lower energy levels of their emission spectra to split, thereby increasing the emission bandwidth. Germanate glass has a high crystal field strength and can increase the Stark splitting of rare-earth luminescent ions. Compared with Er 3+ -doped silica fibers and phosphate fibers, the emission peak of Er 3+ -doped multi-component germanate glass fibers will have an obvious redshift (≥20 nm) in the 1.5 μm band, which can significantly broaden the gain bandwidth of the L band. By adjusting the composition of the germanate glass to control its glass network structure, Ge-O-Ge has multiple Q n (n = 1-4) modes, which can cause more splitting of the energy levels of Er 3+ in the multi-component germanate glass, thereby increasing the emission bandwidth of Er 3+ . In addition, the host glass also needs to meet the requirements of fiber preparation, and needs to have good anti-crystallization performance, mechanical strength, etc. Multi-component germanate glass has good mechanical processing performance and thermal drawing performance, and is an excellent host material for near-infrared laser fibers. Therefore, the selection of the glass host is crucial. The properties of Er 3+ in different glass hosts are unknown. Starting from the goal of realizing broadband luminescence and drawing fibers, the present invention designs a specific glass composition to control the ion coordination local environment of the glass, so that Er 3+ has a synergistic matching effect with the multi-component germanate host glass, realizes broadband luminescence, and at the same time has good thermal drawing performance, and can be prepared into a gain fiber with excellent performance.

[0022] Compared with the prior art, the present invention has the following advantages and effects:

[0023] (1) For the Er 3+ -doped multi-component germanate glass fiber prepared by the present invention, its ASE spectrum covers 1450-1700 nm, its 3 dB bandwidth can reach 80-115 nm, the gain bandwidth range is large, and the luminescence intensity in the C+L band exceeds half of the maximum luminescence intensity value.

[0024] (2) The present invention significantly broadens the gain bandwidth of Er 3+ -doped glass fibers in the 1.5 μm band, can realize multiplexing and demultiplexing of more wave numbers, and further realize the transmission of more optical signals, and can meet the growing needs of high-capacity and high-speed optical communication. The Er 3+ -doped multi-component germanate glass fiber prepared by the present invention provides the core material for 1.5 μm band broadband optical amplifiers.

[0025] (3) The Er 3+ -doped multi-component germanate glass fiber prepared by the present invention provides the core material for 1.5 μm band broadband tunable fiber lasers. Brief Description of the Drawings

[0026] Figure 1 is the ASE (amplified spontaneous emission) spectrum of the Er 3+ -doped multi-component germanate glass fiber prepared in Example 1.

[0027] Figure 2 is a schematic cross-section of the Er 3+ -doped multi-component germanate glass fiber with a fully solid cladding prepared in Example 2.

[0028] Figure 3 is a schematic cross-section of the Er 3+ -doped multi-component germanate glass fiber with a periodically microporous cladding prepared in Example 6. Detailed Description of the Embodiments

[0029] The following are specific implementation cases. Unless otherwise specified, the raw materials used in the implementation cases are all commercially available products.

[0030] Example 1

[0031] In this example, a broadband Er 3+ -doped multi-component germanate glass fiber was prepared. It is a single-mode fiber with a core diameter of 5 μm and a cladding diameter of 125 μm. The fiber cladding is of a fully solid structure. The core is Er 3+ -doped multi-component germanate glass. By mass percentage, the formula is 15% CaO, 10% Al2O3, 65% GeO2, 2.3% La2O3, 0.5% Y2O3, 1.2% Ta2O5, 6% Er2O3. The cladding is multi-component germanate glass. By mass percentage, the formula is 15% CaO, 10% Al2O3, 71% GeO2, 2.3% La2O3, 0.5% Y2O3, 1.2% Ta2O5. The Er 3+ -doped multi-component germanate glass for the core and the multi-component germanate glass for the cladding are both prepared by the melting-annealing method. The surface of the cladding is coated with an acrylic resin polymer layer. The fiber is prepared by the traditional tube-rod method. The specific steps are as follows: Assemble the above two glasses into a fiber preform, heat it to 1000 °C in a commercial fiber drawing tower to soften and deform, and apply a longitudinal tensile force to the glass at this temperature. The glass will extend in this direction and gradually become a fiber.

[0032] The ASE spectrum of the Er 3+ -doped multi-component germanate glass fiber prepared in Example 1 is as Figure 1As shown, it covers 1450 - 1700 nm, its 3dB bandwidth is 115 nm, and in the C+L band, that is, 1530 - 1625 nm, the luminous intensity exceeds half of the maximum luminous intensity value. The maximum gain coefficient of the above-mentioned optical fiber in the 1.5μm band is 5 dB / cm. This optical fiber can be used to build a tunable fiber laser in the 1.5μm band.

[0033] Example 2

[0034] In this example, a broadband Er 3+ -doped multi-component germanate glass optical fiber was prepared. The core diameter of the optical fiber is 4μm, and the diameter of the fiber cladding is 122μm. The fiber cladding is a fully solid structure. The core is Er 3+ -doped multi-component germanate glass. By mass percentage, the formula is 15% CaO, 14% Al2O3, 60% GeO2, 2.3% La2O3, 0.5% Y2O3, 1.2% Ta2O5, 7% Er2O3. The cladding is multi-component silicate glass. By mass percentage, the formula is 69% SiO2, 10% B2O3, 3% BaO, 10% Na2O, 7% K2O, 1% AS2O3. The Er 3+ -doped multi-component germanate glass and multi-component silicate glass are both prepared by the melting-annealing method. The surface of the cladding is coated with a polyimide polymer layer. The optical fiber is prepared by the tube-rod method. The specific steps are to assemble the above two kinds of glass into an optical fiber preform, heat it to 1200°C in a commercial drawing tower to soften and deform, and apply a longitudinal tensile force to the glass at this temperature. The glass will extend in this direction and gradually become an optical fiber.

[0035] The Er 3+ -doped multi-component germanate glass optical fiber prepared in Example 2 has an emission spectrum covering 1450 - 1700 nm, and its 3dB bandwidth is 90 nm. The maximum gain coefficient of the above-mentioned optical fiber in the 1.5μm band is 7 dB / cm. This optical fiber can be used to prepare and build a single-frequency fiber laser in the 1.5μm band.

[0036] Figure 2 is a cross-sectional schematic diagram of the Er 3+ -doped multi-component germanate glass optical fiber with a fully solid structure cladding prepared in Example 2.

[0037] Example 3

[0038] In this example, a broadband Er 3+ -doped multi-component germanate glass optical fiber was prepared. The core diameter of the optical fiber is 10μm, and the diameter of the fiber cladding is 125μm. The fiber cladding is a fully solid structure. The core is Er 3+The doped multi-component germanate glass has a formula of 12% CaO, 14% Al2O3, 60% GeO2, 2.3% La2O3, 0.5% Y2O3, 1.2% Ta2O5, 10% Er2O3 by mass percentage. The cladding is silica glass, and the Er 3+ The doped multi-component germanate glass is prepared by the melting-annealing method. The surface of the cladding is coated with an acrylic resin AC polymer layer. The optical fiber is prepared by the core melting method. The specific steps of the core melting method are as follows: Assemble the above glass into an optical fiber preform, raise the temperature to 1800 °C on a commercial drawing tower to make the core glass of the preform in a molten state. Apply a tensile force in the longitudinal direction to the glass at this temperature. The core of the preform is rapidly cooled into glass during the drawing process and gradually becomes an optical fiber.

[0039] The Er prepared in Example 3 3+ The emission spectrum of the doped multi-component germanate glass optical fiber covers 1450 - 1700 nm, the 3 dB bandwidth is 80 nm, and the maximum gain coefficient of the above optical fiber in the 1.5 μm band is 9 dB / cm. This optical fiber can be used to build an optical amplifier in the 1.5 μm band.

[0040] Example 4

[0041] In this example, a broadband Er 3+ doped multi-component germanate glass optical fiber is prepared. The core diameter of the optical fiber is 12 μm, and the diameter of the optical fiber cladding is 128 μm. The optical fiber cladding is a multi-component germanosilicate glass containing a periodic microporous structure. The core is Er 3+ doped multi-component germanate glass, with a formula of 10% CaO, 8% Al2O3, 70% GeO2, 2.3% La2O3, 0.8% Y2O3, 0.9% Ta2O5, 8% Er2O3 by mass percentage. The cladding is multi-component germanosilicate glass, with a formula of 38% SiO2, 58% GeO2, 2.3% La2O3, 0.8% Y2O3, 0.9% Ta2O by mass percentage. The Er 3+ Both the doped multi-component germanate glass and the multi-component germanosilicate glass are prepared by the melting-annealing method. The prepared cladding glass is also machined to drill holes. The surface of the cladding is coated with a polyimide polymer layer. The optical fiber is prepared by the tube-rod method. The specific steps of the tube-rod method are as follows: Assemble the above two kinds of glass into an optical fiber preform, heat it to 1100 °C on a commercial drawing tower to soften and deform, and apply a tensile force in the longitudinal direction to the glass at this temperature. The glass will extend in this direction and gradually become an optical fiber.

[0042] The Er prepared in Example 4 3+The emission spectrum of the doped multi-component germanate glass fiber covers 1450 - 1700 nm, the 3 dB bandwidth is 102 nm, and the maximum gain coefficient of the above fiber in the 1.5 μm band is 8.5 dB / cm. This fiber can be used to build a mode-locked fiber laser in the 1.5 μm band.

[0043] Example 5

[0044] In this example, a broadband Er 3+ -doped multi-component germanate glass fiber was prepared. The core diameter of the fiber is 9 μm, and the diameter of the fiber cladding is 126 μm. The fiber cladding contains a periodic microporous structure. The core is Er 3+ -doped multi-component germanate glass. By mass percentage, the formula is 8% CaO, 10% Al2O3, 70% GeO2, 1.9% La2O3, 1% Y2O3, 1.1% Ta2O5, 8% Er2O3. The cladding is quartz glass. The Er 3+ -doped multi-component germanate glass was prepared by the melting-annealing method. The prepared cladding glass was also machined to drill holes. A polyimide polymer layer was coated on the cladding surface. The fiber was prepared by the core melting method. The specific steps of the core melting method are as follows: Assemble the above glass into an optical fiber preform, raise the temperature to 1735 °C on a commercial drawing tower to make the core glass in a molten state, apply a longitudinal tensile force to the glass at this temperature, and the core of the preform quickly cools into glass during the drawing process and gradually becomes an optical fiber.

[0045] The Er 3+ -doped multi-component germanate glass fiber prepared in Example 5 has an emission spectrum covering 1450 - 1700 nm, a 3 dB bandwidth of 95 nm, and the maximum gain coefficient of the above fiber in the 1.5 μm band is 7.6 dB / cm. This fiber can be used to build a single-frequency fiber laser in the 1.5 μm band.

[0046] Example 6

[0047] In this example, a broadband Er 3+ -doped multi-component germanate glass fiber was prepared. The core diameter of the fiber is 8 μm, and the diameter of the fiber cladding is 123 μm. The fiber cladding contains a periodic microporous structure. The core is Er 3+ -doped multi-component germanate glass. By mass percentage, the formula is 15% CaO, 10% Al2O3, 62.6% GeO2, 2.1% La2O3, 1% Y2O3, 1.3% Ta2O5, 8% Er2O3. The cladding is multi-component germanate glass. By mass percentage, the formula is 15% CaO, 10% Al2O3, 70.6% GeO2, 2.1% La2O3, 1% Y2O3, 1.3% Ta2O5. The Er 3+Both the doped multi-component germanate glass and the cladding multi-component germanate glass are prepared by the melting-annealing method. The prepared cladding glass is also machined to drill holes. An acrylic resin AC polymer layer is coated on the cladding surface. The optical fiber is prepared by the tube-rod method. The specific steps of the tube-rod method are to assemble the above two kinds of glass into an optical fiber preform, heat it to 960 °C in a commercial drawing tower to soften and deform, and apply a tensile force in the longitudinal direction to the glass at this temperature. The glass will extend in this direction and gradually become an optical fiber.

[0048] The Er prepared in Example 6 3+ The emission spectrum of the doped multi-component germanate glass optical fiber covers 1450 - 1700 nm, the 3 dB bandwidth is 110 nm, and the maximum gain coefficient of the above optical fiber in the 1.5 μm band is 8.3 dB / cm. This optical fiber can be used to build an optical amplifier in the 1.5 μm band.

[0049] Figure 3 is the Er with a periodically microporous structure cladding prepared in Example 6 3+ Schematic cross-sectional view of the doped multi-component germanate glass optical fiber. The micropore diameter is 3 nm.

Claims

1. A broadband Er 3 +-doped multi-component germanate glass optical fiber, characterized in that The optical fiber core is Er 3 +-doped multi-component germanate glass, and the optical fiber cladding is silica glass or multi-component oxide glass; the formula of the optical fiber core is one of the following formulas by mass percentage: 15% CaO, 10% Al₂O₃, 65% GeO₂, 2.3% La₂O₃, 0.5% Y₂O₃, 1.2% Ta₂O₅, 6% Er₂O₃; 15% CaO, 14% Al₂O₃, 60% GeO₂, 2.3% La₂O₃, 0.5% Y₂O₃, 1.2% Ta₂O₅, 7% Er₂O₃; or 12% CaO, 14% Al₂O₃, 60% GeO₂, 2.3% La₂O₃, 0.5% Y₂O₃, 1.2% Ta₂O₅, 10% Er₂O₃; 10% CaO, 8% Al₂O₃, 70% GeO₂, 2.3% La₂O₃, 0.8% Y₂O₃, 0.9% Ta₂O₅, 8% Er₂O₃; 8% CaO, 10% Al₂O₃, 70% GeO₂, 1.9% La₂O₃, 1% Y₂O₃, 1.1% Ta₂O₅, 8% Er₂O₃; 15% CaO, 10% Al₂O₃, 62.6% GeO₂, 2.1% La₂O₃, 1% Y₂O₃, 1.3% Ta₂O₅, 8% Er₂O₃; The amplified spontaneous emission (ASE) spectrum of the optical fiber covers 1450 - 1700 nm; the diameter of the fiber core is 4 - 12 μm, and the diameter of the fiber cladding is 122 - 128 μm; the multi-component oxide glass is selected from two or more of multi-component silicate glass, multi-component germanate glass, and multi-component germano-silicate glass.

2. An Er-doped multi-component germanate glass optical fiber according to claim 1, characterized in that, 3+ The optical fiber is a single-mode optical fiber. ​ 3. A broadband Er 3+ -doped multi-component germanate glass optical fiber according to claim 1, characterized in that, The cladding is of an all-solid structure or contains a periodic microporous structure.

4. A broadband Er 3+ -doped multi-component germanate glass optical fiber according to claim 1, characterized in that The optical fiber further includes a coating layer coated on the surface of the cladding.

5. A broadband Er 3+ -doped multi-component germanate glass optical fiber according to claim 1, characterized in that The Er 3+ doped multi-component germanate glass is prepared by the melting-annealing method, and the optical fiber is prepared by the thermal drawing method, where the thermal drawing method includes the tube-rod method and the core melting method.

6. Use of an Er-doped multi-component germanate glass fiber according to any one of claims 1 to 5 in the preparation of an optical amplifier in the 1.5 μm band. 3+ ​ 7. Use of a broadband Er-doped multi-component germanate glass fiber according to any one of claims 1 to 5 in the preparation of a laser generating element in the 1.5 μm wavelength band. 3+ ​

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