Erbium-doped glass optical fiber used as gain medium and its preparation method and application

Abstract

The present invention belongs to the technical field of glass optical fiber, and discloses an erbium-doped glass optical fiber used as a gain medium, and a preparation method and application thereof. The glass optical fiber is composed of a core and a cladding, and the core is made of the following raw materials in molar percentage: %, SiO 2 :77.5~98,Cs 2 CO 3 :1~20,Er 2 O 3 :0.5~2.5, the cladding is quartz glass. The present invention also discloses a method for preparing glass optical fiber, which is prepared by core melting method, overcoming the problem of limited concentration of hybrid ion doping in preparing erbium-doped gain optical fiber by MCVD method, and effectively solving the limitation of melting point and material properties of preform core material by traditional hot drawing method. The glass optical fiber of the present invention has C-band ultra-narrowband emission, and has obvious characteristics such as small signal amplification, and can be used as gain medium in fiber laser.

Description

Technical Field

[0001] The present invention relates to the technical field of glass optical fibers, and in particular to an erbium-doped glass optical fiber used as a gain medium and a preparation method and application thereof. Background Art

[0002] Since the last century, with the continuous development of information and communication technology, various amplifiers and lasers have been introduced. Among them, fiber amplifiers and lasers are a type of active devices that use doped activated glass optical fibers as gain media. In recent years, based on the needs of coherent detection, lidar and other fields, high-power narrow-linewidth fiber laser technology has attracted much attention. Erbium-doped fiber amplifiers and lasers are one of the most widely used amplifiers and lasers. Narrow-linewidth erbium-doped fiber laser technology has a long history of development and has achieved performance of hundreds of watts of output power and hundreds of hertz of line width. However, due to the low erbium ion doping concentration and high pump energy loss of quartz-based erbium-doped optical fibers, its development is far less than that of single-frequency fiber lasers such as ytterbium-doped fibers.

[0003] Although erbium ions have been doped at high concentrations in some erbium-doped tellurite optical fibers, this type of optical fiber has high splicing loss and poor physical and chemical stability, which brings great difficulties to practical applications (such as: Patent Publication No. CN114180835A). At the same time, due to the wide emission spectrum of heavy metal-based multi-component erbium-doped optical fibers, the single-wavelength emission ratio is low and the energy loss is high. Therefore, it is necessary to explore new hybrid quartz-based erbium-doped optical fibers to meet the requirements of high splicing compatibility, high physical and chemical stability, and high pumping efficiency. However, the exploration of new optical fibers is often restricted by preparation technology.

[0004] Over the years, the preparation technology of erbium-doped gain fibers has been continuously improved, among which the more mature ones include the modified chemical vapor deposition method (MCVD method), the hot pulling method (such as the tube-rod method and the core melting method), etc. However, the MCVD preparation method is limited by the types of industrial raw materials and the limits of solution doping, and the degree of freedom of component regulation of erbium-doped gain fibers is significantly limited in terms of element types and doping concentrations (such as DOI: 10.1006 / ofte.1999.0304); the hot pulling method is limited by the preparation of preform rods, and one of its restrictive factors is the core material that is easy to process, has high density, a melting point (or softening temperature), and material properties that match the quartz cladding (such as: Patent Publication Nos. CN116253522A and CN104609722A). Summary of the invention

[0005] In order to overcome the current problems of limited control freedom of erbium-doped gain fiber components and high pump energy loss, the primary purpose of the present invention is to provide an erbium-doped glass fiber with high melting point, long material length, and high hybrid ion doping concentration as a gain medium. The glass fiber of the present invention has the characteristics of good continuity, clear core-clad interface, high hybrid ion doping concentration, and obvious C-band narrowband small signal amplification.

[0006] Another object of the present invention is to provide a method for preparing erbium-doped glass optical fiber used as a gain medium.

[0007] Another object of the present invention is to provide an application of the erbium-doped glass optical fiber as the above gain medium.

[0008] The purpose of the present invention is achieved through the following technical solutions:

[0009] An erbium-doped glass optical fiber used as a gain medium consists of a core and a cladding, wherein the core is made of the following raw materials in molar percentage: %,

[0010] SiO 2 :77.5~98

[0011] Cs 2 CO 3 :1~20

[0012] Er 2 O 3 :0.5~2.5.

[0013] Preferably, the fiber core is made of the following raw materials in molar percentage: %,

[0014] SiO 2 :83.5~94

[0015] Cs 2 CO 3 :5~15

[0016] Er 2 O 3 :1~1.5.

[0017] Preferably, the cladding is quartz glass;

[0018] The erbium-doped glass optical fiber used as a gain medium is prepared by a core melting method.

[0019] The method for preparing the erbium-doped glass optical fiber used as a gain medium specifically comprises the following steps:

[0020] (1) Preparation of a core glass sinter: The raw materials are mixed evenly, pressed into sheets to obtain a bulk mixture, evenly cut into square sheets, heated to obtain a glass melt, cooled to room temperature to obtain erbium-doped glass, ground into erbium-doped glass powder, sieved, pressed into strips, and sintered at high temperature to obtain a core glass sinter; the raw material is SiO 2 , Cs 2 CO 3 And Er 2 O 3 ;

[0021] (2) Processing of a preform: processing a core glass sintered body into a rod shape, placing the core glass sintered rod in a tubular cladding material to obtain a preform; the diameter of the core glass sintered rod is smaller than the inner diameter of the tubular cladding material; the tubular cladding material is a quartz glass tube;

[0022] (3) Fiber drawing: The preform rod is drawn into an optical fiber, that is, an erbium-doped glass optical fiber used as a gain medium is obtained.

[0023] Preferably, in step (1), the uniform mixing is grinding, and the heating is placing in a gas suspension furnace chamber using CO 2 The laser is used for heating, and the heating temperature is 1700-2000° C.; the high temperature sintering temperature is 1300-1450° C., and the heat preservation time is 4-6 hours.

[0024] Preferably, in step (1), the block mixture is a cylindrical thin sheet block mixture with a diameter of 15 to 20 mm, the size of the square sheet is 3 mm*3 mm to 5 mm*5 mm, the tableting pressure is 2-20 MPa, and the pressure is maintained for 2 to 5 minutes;

[0025] The pressure of the layering strip is 10-30 MPa, and the pressure is maintained for 10-20 minutes to obtain a rectangular block with a size of 40-50 mm*8-10 mm*4-5 mm.

[0026] Preferably, the diameter of the fiber core glass sintered rod in step (2) is 1 to 3 mm, and the fiber core glass sintered rod is polished and pickled before being placed in the tubular cladding material.

[0027] Preferably, in step (1), when Cs 2 CO 3 When the molar percentage is higher than 10%, the raw materials are mixed evenly, and the obtained mixture is directly placed in a mold for molding, and a fiber core glass sintered body is obtained after high-temperature sintering.

[0028] Preferably, the preform rod in step (3) is used to draw an optical fiber in an optical fiber drawing tower. The drawing conditions are as follows: the preform rod is fixed on the drawing tower and argon gas is introduced for protection. The drawing temperature is 2000-2100° C., the drawing speed is 5-30 m / min, and the diameter of the drawn optical fiber is 125 μm.

[0029] The outer layer of the optical fiber is coated with ultraviolet curing resin, and the diameter of the coating layer is 250 μm.

[0030] The erbium-doped glass optical fiber used as a gain medium is used in an optical fiber laser as a gain medium.

[0031] Compared with the prior art, the present invention has the following advantages and effects:

[0032] (1) The method of the present invention overcomes the problem of limited hybrid ion doping concentration in preparing erbium-doped gain optical fiber by MCVD method;

[0033] (2) The method of the present invention effectively solves the limitation of the melting point and material properties of the core layer material of the preform rod by the traditional hot drawing method;

[0034] (3) By adopting the method of the present invention, the erbium-doped glass optical fiber has narrowband emission with high energy concentration and C-band small signal amplification, and it is easier to obtain high-efficiency gain;

[0035] (4) The method of the present invention can be used for the gain medium in a fiber laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a fiber microscope image of the erbium-doped optical fiber prepared in Example 1;

[0037] Figure 2 1 is a fluorescence spectrum diagram of the erbium-doped glass and the quartz erbium-doped glass of Example 1;

[0038] Figure 3 The small signal gain spectrum of the erbium-doped glass optical fiber prepared in Example 1;

[0039] Figure 4 This is a fiber microscope image of the erbium-doped optical fiber prepared in Example 2;

[0040] Figure 5 The fluorescence spectra of the erbium-doped glass and the quartz erbium-doped glass of Example 2;

[0041] Figure 6 The small signal gain spectrum of the erbium-doped glass optical fiber prepared in Example 2;

[0042] Figure 7 This is a fiber microscope image of the hollow-core optical fiber prepared in Comparative Example 1. DETAILED DESCRIPTION

[0043] The present invention will be further described in detail below in conjunction with the examples, but the embodiments of the present invention are not limited thereto. For process parameters not particularly noted, conventional techniques may be used.

[0044] High purity SiO 2 , Cs 2 CO 3 , Er 2 O 3 : Purchased from Aladdin, purity is 99.99%.

[0045] Example 1

[0046] This embodiment provides a method for preparing an erbium-doped gain glass optical fiber, comprising the following steps:

[0047] (1) Select high-purity SiO 2 , Cs 2 CO 3 , Er 2 O 3 As raw materials, SiO 2 :Cs 2 CO 3 :Er 2 O 3 The molar ratio of 94:5:1 was 15 g of the raw materials were weighed, and the raw materials were ground in an agate mortar for 30 min to obtain a fully mixed raw material;

[0048] (2) placing the obtained glass mixture in a mold and pressing the mixture into sheets, setting the pressure to 2-20 MPa, maintaining the pressure for 2-5 min, obtaining a 15 mm cylindrical sheet block mixture, and then evenly cutting it into 3 mm*3 mm square sheets with a blade; using pneumatic suspension melting technology, placing the obtained block in a gas suspension furnace cavity, using CO 2 The laser heats it to 1700-2000℃ to obtain a glass melt, and the CO 2 The laser cools the obtained glass melt to room temperature to obtain the erbium-doped glass.

[0049] (3) Grind the obtained erbium-doped glass into powder using a mortar and pestle, pass the obtained erbium-doped glass powder through an 800-mesh sieve, place the obtained erbium-doped glass powder in a mold, set the pressure to 10-30 MPa, maintain the pressure for 10 to 20 minutes, and obtain a rectangular block with a size of 40 mm*8 mm*4 mm. Use a high-temperature electric furnace to sinter it into a dense fiber core glass sintered body. The sintering process has a sintering temperature of 1400 to 1450°C and is kept warm for 4 hours.

[0050] (4) processing the core glass sintered body obtained in step (3) into a rod with a diameter of 1 to 3 mm, polishing and pickling the core glass sintered rod, and then placing it in a tubular cladding material to obtain a preformed rod; the diameter of the core glass sintered rod is smaller than the inner diameter of the tubular cladding material; the tubular cladding material is a quartz glass tube;

[0051] (5) Drawing the preform rod prepared in (4) into an optical fiber, and drawing the optical fiber in an optical fiber drawing tower; the drawing conditions are as follows: fixing the preform rod on the drawing tower and passing argon gas for protection, the drawing temperature is 2050°C, and the drawing speed is 5-30m / min; the diameter of the optical fiber after drawing is 125μm; the outer layer of the optical fiber is coated with ultraviolet light-curing resin, and the coating layer diameter is 250μm.

[0052] The prepared optical fiber was characterized. Figure 1This is a fiber microscope picture of the erbium-doped optical fiber prepared in Example 1. The prepared erbium-doped glass optical fiber has good light transmission performance, a complete core-clad structure, and good optical fiber flexibility. Figure 2 : is the fluorescence spectrum of the erbium-doped glass prepared in Example 1. The fluorescence full width at half maximum of the erbium-doped glass obtained in Example 1 is 30 nm, which is 10 nm smaller than that of the quartz erbium-doped glass. Figure 3 This is the small signal gain spectrum of the erbium-doped glass fiber prepared in Example 1 under 980nm laser pumping. The obtained erbium-doped glass fiber gain spectrum is similar to the erbium-doped glass fluorescence spectrum. It has C-band narrowband gain under 980nm pumping, a 3dB bandwidth of about 6nm, high energy concentration, and is easier to obtain efficient gain at the central wavelength. It has the potential to be used as a gain medium in narrow-linewidth fiber lasers.

[0053] Example 2

[0054] This embodiment provides a method for preparing an erbium-doped gain glass optical fiber, comprising the following steps:

[0055] (1) Select high-purity SiO 2 , Cs 2 CO 3 , Er 2 O 3 As raw materials, SiO 2 :Cs 2 CO 3 :Er 2 O 3 The molar ratio of 83.5:15:1.5 was 83.5:15:1.5, and 15 g of the raw materials were weighed and ground in an agate mortar for 30 min to obtain a fully mixed raw material;

[0056] (2) The obtained mixed raw material is passed through an 800-mesh sieve, and the obtained mixed raw material powder is placed in a mold for pressing, and the pressure is set to 10-30 MPa, and the pressure is maintained for 10 to 20 minutes to obtain a rectangular block with a size of 40 mm*8 mm*4 mm, which is sintered into a dense fiber core sintered body using a high-temperature electric furnace. The sintering process has a sintering temperature of 1300°C and is kept warm for 4 hours.

[0057] (4) processing the core sintered body obtained in step (3) into a rod with a diameter of 1 to 3 mm, polishing and pickling the core sintered rod, and then placing it in a tubular cladding material to obtain a preformed rod; the diameter of the core sintered rod is smaller than the inner diameter of the tubular cladding material; the tubular cladding material is a quartz glass tube;

[0058] (5) Drawing the preform prepared in (4) into an optical fiber. The optical fiber is drawn in an optical fiber drawing tower; the drawing conditions are that the preform is fixed on the drawing tower and argon gas is introduced for protection, the drawing temperature is 2030°C, and the drawing speed is 5-30m / min; the diameter of the optical fiber after drawing is 125μm; the outer layer of the optical fiber is coated with ultraviolet light curing resin, and the coating layer diameter is 250μm.

[0059] The prepared optical fiber was characterized. Figure 4 This is a fiber microscope picture of the erbium-doped optical fiber prepared in Example 2. The prepared erbium-doped glass optical fiber has good light transmission performance, a complete core-clad structure, and good optical fiber flexibility. Figure 5 This is the fluorescence spectrum of the erbium-doped glass prepared in Example 2. The fluorescence full width at half maximum of the obtained erbium-doped glass is 31 nm, which is 9 nm smaller than that of the quartz erbium-doped glass. Figure 6 This is the small signal gain spectrum of the erbium-doped glass fiber prepared in Example 2 under 980nm laser pumping. The obtained erbium-doped glass fiber gain spectrum is similar to the erbium-doped glass fluorescence spectrum. It has C-band narrowband gain under 980nm pumping, a 3dB bandwidth of about 10nm, high energy concentration, and is easier to obtain efficient gain at the central wavelength. The fiber has ultra-narrowband C-band emission and small signal gain, and has the potential to be used as a gain medium in narrow linewidth fiber lasers.

[0060] Comparative Example

[0061] This comparative example provides a method for preparing an erbium-doped gain glass optical fiber, comprising the following steps:

[0062] (1) Select high-purity SiO 2 , Cs 2 CO 3 , Er 2 O 3 As raw materials, SiO 2 :Cs 2 CO 3 :Er 2 O 3 The molar ratio of 94:5:1 was 15 g of the raw materials were weighed, and the raw materials were ground in an agate mortar for 30 min to obtain a fully mixed raw material;

[0063] (2) filling the obtained mixed raw material powder into a quartz glass cladding with an inner hole, and using a glass rod with a diameter of 1-3 mm to compact the mixed material until it does not naturally fall apart under the action of gravity, thereby obtaining a preform;

[0064] (3) Drawing the preform prepared in (2) into an optical fiber, and drawing the optical fiber in an optical fiber drawing tower; the drawing conditions are as follows: fixing the preform on the drawing tower and introducing argon gas for protection, the drawing temperature is 2050°C, and the drawing speed is 5 to 30 m / min; the diameter of the optical fiber after drawing is 125 μm.

[0065] The prepared optical fiber was characterized. Figure 7 This is a fiber microscope image of the optical fiber prepared in Comparative Example 1. The prepared optical fiber does not have the erbium-doped glass fiber core-cladding structure, and the optical fiber is hollow, wherein the core layer is air and the cladding is quartz, and has no ability to confine light for transmission in the core and the ability to serve as a gain medium.

[0066] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. An erbium-doped glass optical fiber used as a gain medium, Features: The glass optical fiber consists of a core and a cladding, and the core is made of the following raw materials in molar percentage: Not. 2 :83.5~94% Cs 2 WHAT 3 :5~15% Is 2 O 3 :1~1.5%; The cladding is quartz glass; The erbium-doped glass optical fiber used as a gain medium is prepared by a core melting method; specifically comprising the following steps: (1) Preparation of core glass sinter: Mix the raw materials evenly, press them into sheets to obtain a bulk mixture, evenly cut them into square sheets, heat them to obtain a glass melt, cool them to room temperature to obtain erbium-doped glass, grind them into erbium-doped glass powder, sieve them, press them into strips, and sinter them at high temperature to obtain a core glass sinter; (2) Processing of the preform: processing the core glass sintered body into a rod shape, placing the core glass sintered rod in a tubular cladding material to obtain a preform; the diameter of the core glass sintered rod is smaller than the inner diameter of the tubular cladding material; the tubular cladding material is a quartz glass tube; (3) Fiber drawing: The preform is drawn into an optical fiber, that is, an erbium-doped glass optical fiber used as a gain medium is obtained; The heating in step (1) is carried out by placing the mixture in a gas suspension furnace chamber using CO 2 Laser heating is performed at a temperature of 1700~2000 ℃.

2. A method for preparing the erbium-doped glass optical fiber used as a gain medium according to claim 1, Features: The specific steps include: (1) Preparation of core glass sinter: Mix the raw materials evenly, press them into sheets to obtain a bulk mixture, evenly cut them into square sheets, heat them to obtain a glass melt, cool them to room temperature to obtain erbium-doped glass, grind them into erbium-doped glass powder, sieve them, press them into strips, and sinter them at high temperature to obtain a core glass sinter; (2) Processing of the preform: processing the core glass sintered body into a rod shape, placing the core glass sintered rod in a tubular cladding material to obtain a preform; the diameter of the core glass sintered rod is smaller than the inner diameter of the tubular cladding material; the tubular cladding material is a quartz glass tube; (3) Fiber drawing: The preform rod is drawn into an optical fiber, that is, an erbium-doped glass optical fiber used as a gain medium is obtained.

3. The method for preparing the erbium-doped glass optical fiber used as a gain medium according to claim 2, Features: In step (1), the uniform mixing is uniform grinding, the high temperature sintering temperature is 1300-1450° C., and the temperature is kept for 4-6 hours.

4. The method for preparing the erbium-doped glass optical fiber used as a gain medium according to claim 2, Features: In step (1), the block mixture is a cylindrical thin sheet block mixture with a diameter of 15-20 mm, the size of the square thin sheet is 3 mm*3 mm~5 mm*5 mm, the tableting pressure is 2-20 Mpa, and the pressure is maintained for 2-5 min; The pressure of the layering strip is 10-30 Mpa, and the pressure is maintained for 10-20 min to obtain a rectangular block with a size of 40-50 mm*8-10 mm*4-5 mm.

5. The method for preparing the erbium-doped glass optical fiber used as a gain medium according to claim 2, Features: The diameter of the fiber core glass sintered rod in step (2) is 1-3 mm, and the fiber core glass sintered rod is polished and pickled before being placed in the tubular cladding material.

6. The method for preparing the erbium-doped glass optical fiber used as a gain medium according to claim 2, Features: In step (1), when Cs 2 CO 3 When the molar percentage is higher than 10%, the raw materials are mixed evenly, and the resulting mixture is directly placed in a mold for molding, and a core glass sintered body is obtained after high-temperature sintering.

7. The method for preparing the erbium-doped glass optical fiber used as a gain medium according to claim 2, Features: The preform rod in step (3) is used to draw an optical fiber in an optical fiber drawing tower. The drawing conditions are as follows: the preform rod is fixed on the drawing tower and argon gas is introduced for protection. The drawing temperature is 2000-2100 °C, the drawing speed is 5-30 m / min, and the diameter of the drawn optical fiber is 125 μm. The outer layer of the optical fiber is coated with ultraviolet curing resin, and the diameter of the coating layer is 250 μm.

8. The erbium-doped glass optical fiber used as a gain medium according to claim 1 is used in an optical fiber laser. Features: Used as a gain medium.

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