Method for improving near-infrared light emission bandwidth and intensity of bismuth-doped quartz-based material

Abstract

A preferred method for improving the near-infrared emission bandwidth and intensity of bismuth-doped quartz-based materials includes the following steps: placing the bismuth-doped quartz-based material in a sealed reaction vessel, introducing a mixture of reducing and inert gases to bring the reaction vessel to a high-pressure state; heating the reaction vessel to a certain temperature and holding it at that temperature for a period of time, with the heating temperature not lower than 100°C and the holding time being 50-400 hours. Under high temperature and high pressure treatment with a suitable ratio of reducing and inert gas mixture, not only can the number of bismuth near-infrared emission centers be increased, but the fluorescence half-width at half-maximum (FWHM) of the obtained bismuth-doped quartz-based material in the near-infrared band can also be broadened, and the fluorescence intensity improved, showing broad application prospects for expanding communication bands.

Description

Technical Field

[0001] This invention belongs to the field of quartz glass technology, specifically relating to a method for improving the near-infrared emission bandwidth and intensity of bismuth-doped quartz-based materials. Background Technology

[0002] Optical fiber communication is a crucial form of modern communication. The widespread adoption of 5G and the Internet of Things (IoT) have placed increasingly stringent demands on the transmission capacity of optical fibers. Therefore, improving the communication capacity of a single optical fiber is imperative. Currently, the erbium-doped fiber amplifiers (EDFAs) used in optical fiber communication systems operate only in the C+L band, with a bandwidth of approximately 100 nm. Compared to the entire low-loss communication window of 1200 nm-1700 nm in silica optical fibers, this represents a utilization rate of less than 20%, far from meeting the rapidly growing communication demands. Bismuth-doped glass materials, due to their tunable wide-bandwidth luminescence in the 1000-1800 nm band and a full width at half maximum (FWMH) greater than 300 nm, are considered potential gain media for high-speed communication.

[0003] On the other hand, the reported bismuth-doped quartz-based glasses have emission peaks located at 1100nm-1460nm and 1600-1800nm, exhibiting weak fluorescence intensity in the C+L band, which is widely used in communications. This hinders the widespread application of bismuth-doped quartz-based materials. Patents CN103601364A, CN114634311A, CN10588491A, and CN116375349A have proposed many methods to increase the fluorescence intensity of bismuth-doped glasses, but none of them address methods that can effectively control the main fluorescence peak in the C+L band. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a method for improving the near-infrared emission bandwidth and intensity of bismuth-doped quartz-based materials by adjusting the spectral properties of the bismuth-doped quartz-based materials through high-pressure, high-temperature carrier gas treatment.

[0005] To achieve the above objectives, the present invention provides a method for improving the near-infrared emission bandwidth and intensity of bismuth-doped quartz-based materials, comprising the following steps:

[0006] (1) Place the bismuth-doped quartz-based material in a sealed reactor, evacuate it, and then introduce a mixture of reducing gas and inert gas to put the reactor under high pressure.

[0007] (2) Heat the reactor, heat it and keep it warm.

[0008] Preferably, the bismuth-doped quartz-based material is a material with bismuth-doped silicon-based glass as the main component, with a silicon oxide content greater than 45% (molar percentage) and a bismuth oxide content of 0.001% to 1% (molar percentage).

[0009] Preferably, the bismuth-doped quartz-based material is bismuth-germanium co-doped quartz glass or bismuth-germanium silicon-based glass.

[0010] Preferably, the composition (molar percentage) of the bismuth-doped quartz-based material is 49.98SiO2-50GeO2-0.02Bi2O3, and the composition (molar percentage) of the bismuth-doped quartz-based material is 79.98SiO2-20GeO2-0.02Bi2O3.

[0011] Preferably, the reducing gas is one or more of hydrogen, deuterium, and carbon monoxide; the inert gas is one or more of nitrogen, helium, and argon.

[0012] Preferably, the pressure ratio of the reducing gas to the inert gas in the mixture is x MPa:(5-x) MPa, where 0 < x < 5.

[0013] Preferably, the pressure ratio of reducing gas in the mixture is not less than 40%, and the pressure ratio of inert gas is not less than 40%.

[0014] Preferably, the mixed gas is a mixture of deuterium and helium.

[0015] Preferably, the pressure ratio of deuterium to helium is 2 MPa:3 MPa.

[0016] Preferably, in step (1), a mixture of reducing gas and inert gas is introduced into the sealed reactor to ensure that the total pressure inside the reactor is 4 to 6 MPa at room temperature; in step (2), the total pressure inside the reactor is maintained at 10 to 15 MPa during the heat preservation process.

[0017] Preferably, in step (1), the high pressure is 5 MPa; in step (2), the heating temperature is 100℃~500℃ and the holding time is 50h~400h.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] 1) The high pressure effect generated by the mixture of reducing gas and inert gas promotes the entry of gas molecules into the glass network to sensitize bismuth ions. Under the neutralization of the inert gas, the number of low-valence bismuth near-infrared luminescent centers increases.

[0020] 2) During the carrier gas treatment process, the high-temperature environment provides a driving force for the rearrangement of local coordination atoms of bismuth ions, thereby generating new near-infrared luminescent centers and expanding the luminescence range of bismuth ions.

[0021] 3) This invention is applicable to bismuth-doped quartz glass, optical fiber preforms and optical fibers, and has universality.

[0022] 4) The bismuth-doped quartz-based material after carrier gas has a high concentration of bismuth near-infrared active centers and various types of associated near-infrared luminescent centers. Under 808 nm excitation, compared with the original uncarrier-gas glass, its fluorescence peak intensity is enhanced and its full width at half maximum (FWHM) is broadened, covering the E, S, C, L, and U (1360-1675 nm) communication bands. Attached Figure Description

[0023] Figure 1 The image shows a comparison of the 808 nm excitation fluorescence spectra of Examples 1-3 and Comparative Example 1 before and after the glass carrier gas was applied.

[0024] Figure 2 The images show a comparison of the 808 nm excitation fluorescence spectra of Examples 4-6 and Comparative Example 2 before and after the glass carrier gas was used. Detailed Implementation

[0025] To further understand the features, technical means, and achieved objectives and functions of the present invention, specific embodiments of the present invention are described below in conjunction with the accompanying drawings, but the scope of protection is not limited thereto.

[0026] This invention discloses a method for improving the near-infrared emission bandwidth and intensity of bismuth-doped quartz-based materials, comprising the following steps:

[0027] (1) Place the bismuth-doped quartz-based material in a closed reactor and introduce a mixture of reducing gas and inert gas to put the reactor under high pressure.

[0028] (2) Heat the reactor, heat it and keep it warm.

[0029] Specifically, bismuth-doped quartz-based materials are materials whose main component is bismuth-doped silicon-based glass, such as bismuth-doped bulk quartz glass, bismuth-doped quartz fiber preforms, and bismuth-doped quartz fibers. In the embodiments of this invention, the bismuth-doped quartz-based materials are bismuth-germanium co-doped quartz glass and bismuth-germanium silicon-based glass. However, it is known that bismuth-doped quartz fiber preforms and bismuth-doped quartz fibers use bismuth-doped silicon-based glass as the core material, and their near-infrared luminescence characteristics depend almost entirely on the core material. Therefore, this invention is also applicable to other bismuth-doped quartz-based materials whose main component is bismuth-doped silicon-based glass.

[0030] Specifically, reducing gases include, but are not limited to, one or more of hydrogen (H2), deuterium (D2), and carbon monoxide (CO).

[0031] Specifically, the inert gas includes, but is not limited to, one or more of nitrogen (N2), helium (H2), and argon (Ar). Preferably, in step (1), the bismuth-doped quartz-based material is placed in a sealed reaction vessel, and an external vacuum pump is used to evacuate the atmosphere before introducing a mixture of reducing gas and inert gas to prevent oxygen in the air from reacting with the reducing gas. In one specific embodiment, the external vacuum pump evacuates the atmosphere for 10 minutes.

[0032] Preferably, in step (1), a mixture of reducing gas and inert gas is introduced into the sealed reactor to ensure that the total pressure inside the reactor is 4-6 MPa at room temperature. In a specific embodiment, the total pressure inside the reactor is 5 MPa. Preferably, the introduced mixture is a mixture of deuterium and helium. Preferably, the pressure ratio of deuterium to helium is 3 MPa:2 MPa.

[0033] Preferably, in step (2), the total pressure inside the reactor is maintained at 10-15 MPa during the heat preservation process.

[0034] Preferably, in step (2), the heating temperature is 100℃~500℃ and the holding time is 50h~400h.

[0035] Example 1: (See Figure 1 (and Table 1)

[0036] In this embodiment, the sample is bismuth-germanium co-doped quartz glass with a glass composition (molar percentage) of 79.98SiO2-20GeO2-0.02Bi2O3. The carrier gas process for the bismuth-germanium co-doped quartz glass includes: (1) placing the bismuth-germanium co-doped quartz glass in a sealed reactor and evacuating it for 10 minutes using an external vacuum pump; (2) introducing hydrogen into the reactor to make the pressure inside the reactor reach 3MPa, followed by introducing nitrogen to make the total pressure inside the reactor reach 5MPa; (3) placing the reactor in an infrared radiation heating furnace, setting the heating and cooling programs, and holding it at 500℃ for 50 hours, during which the pressure inside the reactor is maintained at 12-15MPa. In step (2), the pressure ratio of hydrogen to nitrogen is 3MPa:2MPa. After the program in step (3) is completed, the sample is taken out, cleaned, polished on both sides, and optically characterized.

[0037] Example 2: (See Example 2) Figure 1 (and Table 1)

[0038] In this embodiment, the sample is bismuth-germanium co-doped quartz glass with a glass composition (molar percentage) of 79.98SiO2-20GeO2-0.02Bi2O3. The carrier gas process for the bismuth-germanium co-doped quartz glass includes: (1) placing the bismuth-germanium co-doped quartz glass in a sealed reactor and evacuating it for 10 minutes using an external vacuum pump; (2) introducing deuterium gas into the reactor to make the pressure inside the reactor reach 2MPa, followed by introducing nitrogen gas to make the total pressure inside the reactor reach 5MPa; (3) placing the reactor in an infrared radiation heating furnace, setting the heating and cooling programs, and holding it at 400℃ for 100 hours, during which the pressure inside the reactor is maintained at 12MPa. In step (2), the pressure ratio of deuterium gas to nitrogen gas is 2MPa:3MPa. After the program in step (3) is completed, the sample is taken out, cleaned, polished on both sides, and subjected to optical characterization.

[0039] Example 3: (See Example 3) Figure 1 (and Table 1)

[0040] In this embodiment, the sample is bismuth-germanium co-doped quartz glass with a glass composition (molar percentage) of 79.98SiO2-20GeO2-0.02Bi2O3. The carrier gas process for the bismuth-germanium co-doped quartz glass includes: (1) placing the bismuth-germanium co-doped quartz glass in a sealed reactor and evacuating it for 10 minutes using an external vacuum pump; (2) introducing a mixture of 95% helium and 5% deuterium into the reactor to achieve a total pressure of 5 MPa; (3) placing the reactor in an infrared radiation heating furnace, setting the heating and cooling programs, and holding it at 100°C for 400 hours, maintaining the pressure inside the reactor at 10 MPa during the holding process. After step (3) is completed, the sample is removed, cleaned, polished on both sides, and subjected to optical characterization.

[0041] Comparative Example 1: (see Figure 1 (and Table 1)

[0042] In this embodiment, the sample is bismuth-germanium co-doped quartz glass with a glass composition (molar percentage) of 79.98SiO2-20GeO2-0.02Bi2O3. The heat preservation process of the bismuth-germanium co-doped quartz glass includes: (1) placing the bismuth-germanium co-doped quartz glass in a sealed reaction vessel and evacuating it for 10 minutes using an external vacuum pump; (2) placing the reaction vessel in an infrared radiation heating furnace, setting the heating and cooling programs, and heat preservation at 400℃ for 100 hours, with the vacuum pump continuously operating during the heat preservation process. After the end of step (2), the sample is taken out, cleaned, polished on both sides, and subjected to optical characterization.

[0043] The fluorescence test results of the bismuth-germanium co-doped quartz glass in Examples 1-3 and Comparative Example 1, excited by a laser at 808 nm, are as follows: Figure 1As shown. A significant difference is that in Comparative Example 1, simply applying heat treatment to the bismuth-germanium co-doped quartz glass did not significantly affect its spectral shape and intensity; in Example 1, the bismuth-germanium co-doped quartz glass treated with a mixed hydrogen and nitrogen carrier gas showed a redshift of the main emission peak from 1400 nm to 1550 nm, and a widening of the half-peak width from 187 nm to 385 nm; in Example 2, the bismuth-germanium co-doped quartz glass treated with a mixed deuterium and nitrogen carrier gas showed a redshift of the main emission peak from 1400 nm to 1580 nm, and a widening of the half-peak width from 187 nm to 330 nm; in Example 3, the bismuth-germanium co-doped quartz glass treated with a mixed helium and a very small amount of deuterium carrier gas showed no change in the main emission peak, but a widening of the half-peak width from 187 nm to 273 nm. Treatment under weak reducing conditions can also enhance the fluorescence intensity of bismuth ions, but compared to a strongly reducing mixed gas, this condition only induces a small number of new luminescent centers. The bismuth-germanium co-doped quartz glass emission band treated with the high-pressure and high-temperature carrier gas of this invention covers the E, S, C, L, and U (1360-1675nm) communication bands.

[0044] This indicates that the high pressure effect generated by the mixture of reducing and inert gases promotes the entry of gas molecules into the glass network to sensitize bismuth ions. Under the neutralization effect of the inert gas, the number of near-infrared luminescent centers of low-valence bismuth increases. At the same time, under the action of high temperature, the glass structure is relatively loose, which promotes the rearrangement of coordinating atoms around low-valence bismuth ions and generates new near-infrared luminescent centers.

[0045] Example 4: (See Example 4) Figure 2 (and Table 1)

[0046] In this embodiment, the sample is bismuth-germanium silicon-based glass with a glass composition (molar percentage) of 49.98SiO2-50GeO2-0.02Bi2O3. The carrier gas process for the bismuth-germanium silicon-based glass includes: (1) placing the bismuth-germanium silicon-based glass in a sealed reactor and evacuating it for 10 minutes using an external vacuum pump; (2) introducing hydrogen into the reactor to make the pressure inside the reactor reach 3MPa, followed by introducing nitrogen to make the total pressure inside the reactor reach 5MPa; (3) placing the reactor in an infrared radiation heating furnace, setting the heating and cooling programs, and holding it at 500℃ for 50 hours, during which the pressure inside the reactor is maintained at 12-15MPa. In step (2), the pressure ratio of hydrogen to nitrogen is 3MPa:2MPa. After the program in step (3) is completed, the sample is taken out, cleaned, polished on both sides, and subjected to optical characterization.

[0047] Example 5: (See Example 5) Figure 2 (and Table 1)

[0048] In this embodiment, the sample is a bismuth-germanium silicon-based glass, and the composition (molar percentage) of the glass is: 49.98SiO2-50GeO2-0.02Bi2O3. The carrier gas process of the bismuth-germanium silicon-based glass includes: (1) placing the bismuth-germanium silicon-based glass in a sealed reaction vessel and evacuating it for 10 minutes using an external vacuum pump; (2) introducing deuterium gas into the reaction vessel to make the pressure inside the reaction vessel reach 2MPa, and then introducing nitrogen gas to make the total pressure inside the reaction vessel reach 5MPa; (3) placing the reaction vessel in an infrared radiation heating furnace, setting the heating and cooling programs, and holding it at 400℃ for 100 hours, during which the pressure inside the reaction vessel is maintained at 12MPa. In step (2), the pressure ratio of deuterium gas to nitrogen gas is 2MPa:3MPa. After the program in step (3) is completed, the sample is taken out, cleaned, polished on both sides, and optically characterized.

[0049] Example 6: (See Example 6) Figure 2 (and Table 1)

[0050] In this embodiment, the sample is bismuth-germanium silicon-based glass, and the composition (molar percentage) of the glass is: 49.98SiO2-20GeO2-0.02Bi2O3. The carrier gas process of the bismuth-germanium silicon-based glass includes: (1) placing the bismuth-germanium silicon-based glass in a sealed reaction vessel and evacuating it for 10 minutes using an external vacuum pump; (2) introducing a mixture of 95% helium and 5% deuterium into the reaction vessel to make the total pressure inside the reaction vessel reach 5MPa; (3) placing the reaction vessel in an infrared radiation heating furnace, setting the heating and cooling programs, and holding it at 100℃ for 400 hours, during which the pressure inside the reaction vessel is maintained at 10MPa. After the program in step (3) is completed, the sample is taken out, cleaned, polished on both sides, and optically characterized.

[0051] Comparative Example 2: (see Figure 2 (and Table 1)

[0052] In this embodiment, the sample is bismuth-germanium silicon-based glass with a glass composition (molar percentage) of 49.98SiO2-50GeO2-0.02Bi2O3. The carrier gas process for the bismuth-germanium silicon-based glass includes: (1) placing the bismuth-germanium silicon-based glass in a sealed reactor and evacuating it for 10 minutes using an external vacuum pump; (2) placing the reactor in an infrared radiation heating furnace, setting the heating and cooling programs, and holding it at 400℃ for 100 hours, with the vacuum pump continuously operating during the holding process. After step (2) is completed, the sample is removed, cleaned, polished on both sides, and subjected to optical characterization.

[0053] The fluorescence test results of the bismuth-germanium-doped silicon-based glasses in Examples 4-6 and Comparative Example 2, excited by a laser at 808 nm, are as follows: Figure 2As shown. The significant difference is that Comparative Example 2 only extended the full width at half maximum (FWHM) of the emission peak by heat preservation treatment of the bismuth-germanium-doped silicon-based glass; while the treatment with a hydrogen / nitrogen mixed gas (Example 4) or a 95% helium and 5% deuterium mixed gas (Example 6) carrier gas significantly changed the emission spectrum of the bismuth-germanium-doped silicon-based glass, that is, the 1400nm main emission peak transformed into a broad spectrum with superimposed double peaks of 1400nm and 1560nm, and the FWHM was broadened from 238nm to more than 400nm, and the emission band covered the O, E, S, C, L, U (1260-1675nm) communication band; in Example 5, the main emission peak of the bismuth-germanium-doped silicon-based glass after using a deuterium and nitrogen mixed gas carrier gas was redshifted from 1400nm to 1600nm, and the FWHM was broadened from 238nm to 312nm.

[0054] This indicates that the high-pressure effect generated by the mixture of reducing and inert gases induces gas molecules to enter the glass network and sensitize bismuth ions. Under the neutralization effect of the inert gas, the number of near-infrared luminescent centers of low-valence bismuth increases. Simultaneously, the relatively loose glass structure under high temperature promotes the rearrangement of coordinating atoms around the low-valence bismuth ions, generating new near-infrared luminescent centers.

[0055] Table 1 compares the main peak position, half-peak width, and fluorescence changes at 1400 nm and 1550 nm between Examples 1-6, Comparative Examples 1-2, and the original samples.

[0056] Table 1

[0057]

[0058] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for improving the near-infrared emission bandwidth and intensity of bismuth-doped quartz-based materials, characterized in that, Includes the following steps: (1) Place the bismuth-doped quartz-based material in a sealed reactor, evacuate it, and then introduce a mixture of reducing gas and inert gas to put the reactor under high pressure. (2) Heat the reactor and keep it at that temperature; The bismuth-doped quartz-based material is a material with bismuth-doped silicon-based glass as the main component, with a silicon oxide content greater than 45% molar percentage and a bismuth oxide content of 0.001% to 1% molar percentage; In step (1), a mixture of reducing gas and inert gas is introduced into the sealed reactor to ensure that the total pressure inside the reactor is 4-6 MPa at room temperature; in step (2), the total pressure inside the reactor is maintained at 10-15 MPa during the heat preservation process. In step (2), the heating temperature is 100℃~500℃ and the holding time is 50h~400h.

2. The method according to claim 1, characterized in that, The bismuth-doped quartz-based material is either bismuth-germanium co-doped quartz glass or bismuth-germanium silicon-based glass.

3. The method according to claim 1, characterized in that, The bismuth-doped quartz-based material has a molar percentage of 49.98SiO2-50GeO2-0.02Bi2O3 or a molar percentage of 79.98SiO2-20GeO2-0.02Bi2O3.

4. The method according to claim 1, characterized in that, The reducing gas is one or more of hydrogen, deuterium, and carbon monoxide; the inert gas is one or more of nitrogen, helium, and argon.

5. The method according to claim 1, characterized in that, The pressure ratio of the reducing gas to the inert gas in the mixture is x MPa:(5-x) MPa, where 0 < x < 5.

6. The method according to claim 5, characterized in that, The pressure ratio of reducing gas in the mixture is not less than 40%, the pressure ratio of inert gas is not less than 40%, and the sum of the two is 100%.

7. The method according to claim 4, characterized in that, The mixed gas is a mixture of deuterium and helium.

8. The method according to claim 7, characterized in that, The pressure ratio of the deuterium and helium is 2 MPa:3 MPa.

9. The method according to claim 1, characterized in that, In step (1), the total pressure inside the reactor at room temperature is 5 MPa.

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