Radiation-resistant erbium-ytterbium co-doped silica fiber with high laser performance and preparation method thereof

Abstract

The invention relates to a radiation-resistant erbium-ytterbium co-doped silica optical fiber with high laser performance and a preparation method thereof, and relates to the field of optical fiber manufacturing, the radiation-resistant erbium-ytterbium co-doped silica optical fiber comprises a fiber core, a cladding layer and a coating layer; the Er-Yb-Al-P co-doped optical fiber is characterized in that the fiber core is made of Er-Yb-Al-P co-doped silica glass; the cladding is made of a quartz-based glass material; and the coating layer is composed of a fluorine-doped acrylate material with a low refractive index and an acrylate material with a high refractive index. The erbium-ytterbium co-doped optical fiber is prepared by adopting an improved chemical vapor deposition (MCVD) combined solution doping method, Ce is not co-doped in the preparation process, and Al is co-doped, so that the laser performance of the irradiation-resistant erbium-ytterbium co-doped optical fiber can be greatly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical fiber preparation, and particularly relates to a radiation-resistant erbium-ytterbium co-doped quartz optical fiber with high laser performance and a preparation method thereof. BACKGROUND

[0002] The radiation-resistant erbium-ytterbium co-doped quartz optical fiber is widely used in the field of space laser communication, etc. However, under the action of space rays, the laser gain provided by the erbium-ytterbium co-doped quartz optical fiber will gradually decrease, resulting in a decrease in the output of the fiber laser.

[0003] It has been proved in documents that the decrease in the radiation resistance of the optical fiber is mainly caused by the color center formed by the P element in the irradiation process, resulting in an increase in the loss of the optical fiber (DOI: 10.1109 / jlt.2012.2233196). In the erbium-ytterbium optical fiber, in order to improve the solubility and dispersity of the Er and Yb light-emitting rare earth elements, co-doped elements are necessary (DOI: 10.7567 / 1347-4065 / ab17e4), and the radiation resistance of the optical fiber cannot be improved by removing the P element.

[0004] The main technology at present is to improve the radiation resistance of the optical fiber in the space ray environment by doping an aliovalent element (mainly Ce, and also including Ge, etc.), such as 202411383405.8, 201910872955.9, etc., but it will cause a decrease in the laser performance of the erbium-ytterbium co-doped quartz optical fiber, so that the laser slope efficiency of the radiation-resistant erbium-ytterbium co-doped quartz optical fiber is lower than that of the conventional erbium-ytterbium co-doped quartz optical fiber. At the same time, the doping of the Ce and Ge elements will cause an increase in the refractive index of the fiber core, and the numerical aperture needs to be adjusted by controlling the refractive index of the fiber core, which also causes the Er and Yb rare earth elements in the fiber core to be unable to obtain a higher doping concentration, finally resulting in a decrease in the overall light-emitting efficiency. Therefore, in the current technical route of component optimization, the laser performance of the optical fiber is decreased to different degrees. SUMMARY

[0005] In order to solve the problem of relatively poor laser performance of the radiation-resistant erbium-ytterbium co-doped optical fiber, the present application provides a radiation-resistant erbium-ytterbium co-doped quartz optical fiber with high laser performance and a preparation method thereof. The Ce element is not doped, the Al element is additionally doped, and the components of the optical fiber are adjusted. The laser performance is improved by more than 13% while the radiation resistance is similar to that of the Ce-doped radiation-resistant optical fiber.

[0006] In a first aspect, the present application provides a radiation-resistant erbium-ytterbium co-doped quartz optical fiber with high laser performance. The erbium-ytterbium co-doped quartz optical fiber comprises, from inside to outside, a quartz core, a quartz cladding and a coating layer, wherein

[0007] The quartz core is composed of Er, Yb, Al and P co-doped silica glass;

[0008] The quartz cladding is made of quartz-based glass material;

[0009] The coating layer includes a low-refractive-index coating inner layer directly coated outside the quartz cladding and a high-refractive-index coating outer layer covering the inner layer.

[0010] Further, the concentration of the quartz core doping components ranges from Er: 0.10-0.35wt%, Yb: 2.5-5.0wt%, Al: 0.05-1.5wt%, and P: 5.0-9.0wt%.

[0011] Preferably, the concentration of the quartz core doping components ranges from Er: 0.15-0.35wt%, Yb: 3.0-4.5wt%, Al: 0.5-1.5wt%, and P: 7.5-9.0wt%.

[0012] Further, the diameter of the quartz core ranges from 4 to 40μm.

[0013] Further, the numerical aperture of the quartz core ranges from 0.05 to 0.25.

[0014] Further, the cross-sectional shape of the quartz cladding of the quartz optical fiber is a regular polygon.

[0015] More specifically, the regular polygon is a regular octagon, and the ratio of the longest diagonal of the quartz cladding of the quartz optical fiber to the diameter of the quartz core ranges from 3 to 35.

[0016] Further, the quartz optical fiber cladding includes a pair of axisymmetric stress regions, which form a polarization maintaining fiber structure, and the birefringence coefficient of the quartz optical fiber at a wavelength of 1550nm is greater than 1*10 -4 .

[0017] More specifically, the stress regions are circular boron-doped quartz rods, the ratio of the diameter of the boron-doped quartz rod to the diameter of the quartz core ranges from 1 to 10, and the ratio of the distance between the center of the boron-doped quartz rod and the center of the quartz core to the diameter of the quartz core ranges from 2 to 15.

[0018] Further, the low-refractive-index coating inner layer is made of fluorine-doped acrylate material, and the high-refractive-index coating outer layer is made of acrylate material.

[0019] Further, the background loss of the quartz optical fiber at a wavelength of 1200nm is less than 50dB / km, the cladding absorption at 915nm is greater than 1.5dB / m, and the core absorption at 1535nm is greater than 20dB / m.

[0020] In another aspect, the present application also provides a preparation method of a high-laser-performance radiation-resistant erbium-ytterbium co-doped quartz optical fiber, mainly including the following steps:

[0021] S1: preparing a preform core rod of a quartz optical fiber, wherein a fiber core part is Er, Yb, Al, P co-doped silica glass, and a tube wall is quartz;

[0022] S2: processing a preform sleeve, and selecting a processing method according to a required fiber type, mainly including:

[0023] a) for a non-polarization maintaining optical fiber, processing a cross section of the sleeve into a regular polygon; or

[0024] b) for a polarization maintaining optical fiber, punching symmetric circular holes on both sides of the sleeve and inserting a boron-doped quartz rod;

[0025] S3: combining the preform core rod and the preform sleeve obtained in steps S1 and S2 to draw into an optical fiber, and sequentially coating the outer part with an inner layer of a low refractive index material and an outer layer of a high refractive index material;

[0026] Optionally, when there is a higher requirement on the radiation resistance of the optical fiber, the preparation method further includes:

[0027] S4: pretreating the optical fiber obtained in step S3, including carrier gas treatment and irradiation treatment in sequence.

[0028] Further, in the step S1, the preparation of the preform core rod adopts a modified chemical vapor deposition method (MCVD) combined with a solution doping method.

[0029] Further, in the step S2, the regular polygon is a regular octagon.

[0030] Further, in the step S2, a ratio of the diameter of the circular hole to the diameter of the fiber core is 1.0-9.0, and a ratio of a distance between the edge of the circular hole and the edge of the quartz fiber core to the diameter of the fiber core is 0.5-8.0.

[0031] Further, in the step S4, the carrier gas treatment satisfies the following conditions: the carrier gas environment is a mixed gas of deuterium and helium, wherein the deuterium accounts for 20%-100%, the pressure is 4-8 MPa, the temperature is 25-80℃, and the carrier gas treatment time is 12-720 hours.

[0032] Further, in the step S4, the irradiation treatment satisfies the following conditions: the irradiation environment is X-ray or γ-ray, the irradiation dose rate is 0.2-50 krad / min, and the total irradiation dose is 20-500 krad.

[0033] Compared with the prior art, the present application has the following advantages:

[0034] Since the core numerical aperture needs to be controlled in the optical fiber, the Er and Yb element concentration affecting the fiber laser performance in the core is limited. Compared with the existing radiation-resistant erbium-ytterbium co-doped optical fiber, the optical fiber prepared by the application optimizes the doping elements and content, removes the Ce element, and adds a certain amount of Al element. Since the influence of the Al element on the core numerical aperture is relatively small, the doping concentration of the Er and Yb elements can be increased, so that the optical fiber has a higher cladding absorption coefficient, and the laser efficiency and output power are increased by more than 13%;

[0035] In addition to the above advantages, compared with the existing radiation-resistant erbium-ytterbium co-doped optical fiber, since a certain amount of Al element is doped, even if the Ce element is not doped, the optical fiber prepared by the application does not have obvious weakening in the radiation resistance performance;

[0036] In addition to the above advantages, the application can be pre-processed according to the actual needs, and in the case of partially reducing the laser performance of the optical fiber, the radiation resistance performance of the optical fiber can be greatly improved (the power attenuation is reduced by more than 60% under the same environment);

[0037] Compared with the preparation method of the traditional optical fiber, the preparation difficulty of the optical fiber of the application is similar, the processing process is relatively simple, and it is easy to produce and manufacture; there is no special requirement, and it can be used to prepare a regular octagonal radiation-resistant erbium-ytterbium co-doped optical fiber or a panda type polarization maintaining radiation-resistant erbium-ytterbium co-doped optical fiber. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 is the technical roadmap provided by the application;

[0039] Figure 2 is a structural schematic diagram of a high-laser-performance non-polarization radiation-resistant erbium-ytterbium co-doped quartz optical fiber provided by the embodiment of the application;

[0040] Figure 3 is a structural schematic diagram of a high-laser-performance polarization maintaining radiation-resistant erbium-ytterbium co-doped quartz optical fiber provided by the embodiment of the application;

[0041] Figure 4 (a) is a graph of the relationship between the laser output power and the pump power of the comparative example 2 and the comparative example 4 of the application; (b) is a graph of the laser gain change under continuous irradiation of the comparative example 2 and the comparative example 4 of the application;

[0042] Figure 5 (a) is a graph of the relationship between the laser output power and the pump power of the embodiment 1 and 2 and the comparative example 1 and 2 of the application; (b) is a graph of the laser gain change under continuous irradiation of the embodiment 1 and 2 and the comparative example 1 and 2 of the application;

[0043] Figure 6(a) is a graph of laser output power versus pump power for inventive examples 2 and 3 and comparative examples 2 and 3; (b) is a graph of laser gain variation under continuous irradiation for inventive examples 2 and 3 and comparative examples 2 and 3;

[0044] Figure 7 (a) is a graph of laser output power versus pump power for inventive example 3 and comparative example 2; (b) is a graph of laser gain variation under continuous irradiation for inventive example 3 and comparative example 2;

[0045] Figure 8 (a) is a graph of laser output power versus pump power for inventive comparative example 5 and inventive example 2; (b) is a graph of laser gain variation under continuous irradiation for inventive comparative example 5 and inventive example 2;

[0046] Figure 9 (a) is a graph of laser output power versus pump power for inventive comparative examples 2, 5 and inventive examples 2, 5, 6; (b) is a graph of laser gain variation under continuous irradiation for inventive comparative examples 2, 5 and inventive examples 2, 5, 6;

[0047] BRIEF DESCRIPTION OF DRAWINGS

[0048] 1 - quartz core; 2 - octagonal quartz cladding; 3a - inner layer of low refractive index coating; 3b - outer layer of high refractive index coating; 4 - circular quartz cladding with stress region; 5 - boron-doped quartz rod. DETAILED DESCRIPTION

[0049] It should be noted that these embodiments are provided so that the disclosure can be more thoroughly understood, and so that the scope of the disclosure can be completely conveyed to those skilled in the art, and the disclosure can be implemented in various forms, and should not be limited by the embodiments set forth herein.

[0050] Figure 1 The technical roadmap of the present disclosure is as follows:

[0051] 1) Preparation of preform rod: an erbium-ytterbium co-doped optical fiber preform rod core rod is prepared by a modified chemical vapor deposition (MCVD) method combined with a solution doping method, the core rod core region is an Er-Yb-Al-P co-doped silica glass, the theoretical doping composition range is: Er: 0.10-0.35wt%, Yb: 2.5-5.0wt%, Al: 0.01-1.50wt%, P: 5.0-8.5wt%, and the tube wall is pure quartz;

[0052] 2) Preform rod processing: the quartz sleeve is adjusted in geometric structure according to requirements, and then polished, the geometric structure adjustment includes but is not limited to:

[0053] When preparing non-deflected optical fiber, the cross-sectional structure is changed, the outer wall of the sleeve is processed into a regular octagon, and the ratio of the cladding diagonal to the quartz core diameter is 3-35;

[0054] When preparing polarization-maintaining optical fiber, microstructure holes are processed. Two axially symmetrical circular holes are drilled in the cross section of the sleeve. The ratio of the diameter of the circular hole to the diameter of the core area is 1.0-9.0, and the ratio of the distance between the edge of the circular hole and the edge of the quartz core to the core diameter is 0.5-8.0. Then, a boron-doped quartz rod of the same specifications is inserted;

[0055] 3) Preform drawing: The finished preform core rod and sleeve are combined and drawn into an optical fiber, and the outermost layer is coated with a low refractive index coating inner layer and a high refractive index coating outer layer in sequence;

[0056] Furthermore, according to actual requirements for radiation resistance, the optical fiber in step 3) may be pretreated as follows:

[0057] 4) Fiber pretreatment: including:

[0058] 4a) Carrier gas treatment: placing the optical fiber in a mixture of deuterium and helium, wherein the deuterium accounts for 20% to 100%, the pressure is 4 to 8 MPa, the temperature is 25 to 80° C., and the carrier gas treatment time is 12 to 720 hours;

[0059] 4b) irradiation treatment: placing the optical fiber described in 4a) under X-rays, irradiating 20-500 krad at a dose rate of 0.2-50 krad / min;

[0060] In order to evaluate the various performance indicators of the optical fiber prepared by the present invention, the optical fiber was subjected to the following performance tests:

[0061] 5) Performance Testing: A fiber amplifier was constructed using the prepared optical fiber, and the laser output power and laser slope efficiency under the same conditions were tested to characterize the laser efficiency of the optical fiber. Simultaneously, the optical fiber prepared by the present invention in the optical fiber amplifier was placed under the same irradiation source, and the change in laser output power under the same conditions was tested to characterize the radiation resistance of the optical fiber.

[0062] The non-biased radiation-resistant erbium-ytterbium co-doped optical fiber obtained by the preparation method in the above technical route has a structural schematic diagram as shown in FIG. Figure 2 As shown, it includes a quartz core 1, a regular octagonal quartz cladding 2, an inner coating layer 3a, and an outer coating layer 3b;

[0063] The structure diagram of the polarization-maintaining radiation-resistant erbium-ytterbium co-doped optical fiber obtained by the preparation method in the above technical route is as follows: Figure 3 As shown, it includes a quartz fiber core 1, a circular quartz cladding 4 containing a stress region, an inner coating layer 3a, an outer coating layer 3b, and a boron-doped quartz rod 5;

[0064] The radiation-resistant Er-Yb co-doped quartz optical fiber and the manufacturing method thereof of the present application are specifically described below through five specific comparative examples and five examples:

[0065] Comparative Example 1

[0066] The Er-Yb co-doped optical fiber comprises, from the center of the circle outward, a quartz core, a quartz cladding, a low-refractive-index coating inner layer and a high-refractive-index coating outer layer; the quartz core is Er-Yb-P-Ce co-doped silica glass, the doping component concentration is: Er: 0.15wt%, Yb: 3.0wt%, P: 7.5wt%, Ce: 1.0wt%, and the diameter is 12μm; the quartz cladding is pure quartz, and the cross section is regular octagon; the numerical aperture (NA) between the quartz core and the quartz cladding is 0.19, and the NA between the quartz cladding and the low-refractive-index coating inner layer is 0.46; the component of the low-refractive-index coating inner layer is fluorine-doped acrylate; the component of the high-refractive-index coating outer layer is acrylate; the ratio of the diameter of the quartz core to the diagonal of the cladding is 1:10.42; the background loss of the optical fiber is 20dB / km, the 915nm cladding absorption is 2.3dB / m, and the 1535nm core absorption is 42dB / m;

[0067] The main preparation process steps are as follows:

[0068] 1) Preparation of preform rod: an Er-Yb co-doped optical fiber preform rod core rod is prepared by using a modified chemical vapor deposition (MCVD) method combined with a solution immersion process;

[0069] 2) Processing of preform rod: the outer tube wall of the quartz sleeve is polished to octagon and polished;

[0070] 3) Preform rod drawing: the processed preform rod core rod and the sleeve are combined and drawn into an optical fiber, and the low-refractive-index coating inner layer and the high-refractive-index coating outer layer are sequentially wrapped outside the quartz cladding;

[0071] 4) Performance test: an optical fiber amplifier is built using the optical fiber, a 200mW 1550nm signal light and a 0-12W 940nm reverse pumping light are fixed to work under the condition, the maximum laser output power and the laser slope efficiency are tested; under the above laser performance test condition, the optical fiber in the optical fiber amplifier is placed under the irradiation of high-energy X-rays with a dose rate of 60Gy / h, the continuous irradiation dose is 100Gy, and the change of the laser output power is recorded.

[0072] Comparative Example 2

[0073] The erbium-ytterbium co-doped optical fiber comprises, from the center outward, a quartz core, a quartz cladding, a low refractive index coating inner layer, and a high refractive index coating outer layer; in addition, the quartz cladding further comprises two circular boron-doped quartz rods, which are symmetrically distributed around the quartz core; the quartz core is Er-Yb-P-Ce co-doped silica glass, and the doping component concentrations are: Er: 0.15wt%, Yb: 3.0wt%, P: 7.5wt%, and Ce: 1.0wt%, and the diameter is 12μm; the quartz cladding is pure quartz, and the cross section is circular; the numerical aperture (NA) between the quartz core and the quartz cladding is 0.19, and the NA between the quartz cladding and the low refractive index coating inner layer is 0.46; the composition of the low refractive index coating inner layer is fluorine-doped acrylate; the composition of the high refractive index coating outer layer is acrylate; the ratio of the diameter of the quartz core to the diameter of the cladding is 1:10.42; the ratio of the diameter of the quartz core to the diameter of the boron-doped quartz rod is 1:3, and the ratio of the diameter of the quartz core to the distance between the center of the boron-doped quartz rod and the center of the quartz core is 1:2.9; the background loss of the optical fiber is 29dB / km, the 915nm cladding absorption is 2.7dB / m, and the 1535nm core absorption is 41dB / m; the birefringence coefficient of the optical fiber is 1.56*10 -4 .

[0074] The main preparation process steps are as follows:

[0075] 1) Preparation of a preform rod: an erbium-ytterbium co-doped optical fiber preform rod core rod is prepared by using a modified chemical vapor deposition (MCVD) method combined with a solution immersion process;

[0076] 2) Processing of the preform rod: two axisymmetric circular holes are punched on both sides of a quartz sleeve tube with the core as the center, and then polishing treatment is performed, and a boron-doped quartz rod is inserted;

[0077] 3) Preform rod drawing: the processed preform rod core rod and the sleeve tube are combined and drawn into an optical fiber, and a low refractive index coating inner layer and a high refractive index coating outer layer are sequentially wrapped outside the quartz cladding;

[0078] 4) Performance testing: an optical fiber amplifier is built using the optical fiber, and the maximum laser output power and the laser slope efficiency are tested under the condition that the working 200mW 1550nm signal light and 0-12W 940nm reverse pumping light are fixed; under the above laser performance test conditions, the optical fiber in the optical fiber amplifier is placed under high-energy X-rays with a dose rate of 60Gy / h, and the continuous irradiation dose is 100Gy, and the change of the laser output power is recorded;

[0079] Comparative Example 3

[0080] A high laser performance radiation resistant Er-Yb co-doped quartz optical fiber, the fiber parameters are the same as those of the comparative example 2, the background loss of the fiber is 35 dB / km, the 915 nm cladding absorption is 2.7 dB / m, and the 1535 nm core absorption is 41 dB / m; the birefringence coefficient of the fiber is 1.56*10 -4 .

[0081] The comparative example 3 is prepared on the basis of the fiber preparation process flow of the comparative example 2, and a pretreatment step is added, and other preparation steps are the same as those of the comparative example 2. The Er-Yb co-doped fiber prepared has the following steps after 3) preform rod drawing:

[0082] 4) pretreatment, including:

[0083] 4a) carrier gas treatment: the fiber is placed in a mixed gas of deuterium and helium, wherein the deuterium accounts for 50%, the pressure is 5 MPa, and the temperature is 65°C, and the carrier gas treatment time is 120 hours;

[0084] 4b) irradiation treatment: the fiber is placed under X-ray irradiation, the irradiation is 200 krad, and the dose rate is 2 krad / min;

[0085] 5) vacuum treatment: the fiber is placed in an environment with a pressure of less than 10 Pa for 240 hours; this step is to simulate a vacuum environment to exclude the influence of residual gas in the pretreatment on the radiation resistance performance test.

[0086] In addition, the original 4) performance test is changed to 6) performance test

[0087] Comparative example 4

[0088] A high laser performance radiation resistant Er-Yb co-doped quartz optical fiber, other fiber parameters are the same as those of the comparative example 2, except that the theoretical composition of the quartz core of the Er-Yb co-doped fiber prepared is: Er: 0.15wt%, Yb: 3.0wt%, P: 7.0wt%, and Ce: 1.3wt%; the background loss of the fiber is 31 dB / km, the 915 nm cladding absorption is 2.6 dB / m, and the 1535 nm core absorption is 42 dB / m; the birefringence coefficient of the fiber is 1.62*10 -4 .

[0089] The preparation steps are the same as those of the comparative example 2.

[0090] Comparative example 5

[0091] A high laser performance radiation resistant Er-Yb co-doped quartz optical fiber, other fiber parameters are the same as those of the comparative example 2, except that the prepared Er-Yb co-doped fiber has a quartz core theoretical composition of Er: 0.30wt%, Yb: 4.5wt%, and P: 8.5wt%; the background loss of the fiber is 25dB / km, the 915nm cladding absorption is 3.3dB / m, and the 1535nm core absorption is 63dB / m; the birefringence coefficient of the fiber is 1.58*10 -4 .

[0092] The preparation steps are the same as those of the comparative example 2.

[0093] Examples 1-3 described below respectively use the same preparation process as comparative examples 1-3, except that the conventional doping system in the comparative examples is replaced by the optimized doping system of the application, and the remaining process parameters remain unchanged.

[0094] Example 1

[0095] A high laser performance radiation resistant Er-Yb co-doped quartz optical fiber, other fiber parameters are the same as those of the comparative example 1, except that the prepared Er-Yb co-doped fiber has an Er-Yb-Al-P co-doped silica glass quartz core with a theoretical composition of Er: 0.30wt%, Yb: 4.5wt%, Al: 0.5wt%, and P: 7.5wt%; the background loss of the fiber is 18dB / km, the 915nm cladding absorption is 3.6dB / m, and the 1535nm core absorption is 69dB / m;

[0096] The preparation steps are the same as those of the comparative example 1.

[0097] Example 2

[0098] A high laser performance radiation resistant Er-Yb co-doped quartz optical fiber, other fiber parameters are the same as those of the comparative example 2, except that the prepared Er-Yb co-doped fiber has an Er-Yb-Al-P co-doped silica glass quartz core with a theoretical composition of Er: 0.30wt%, Yb: 4.5wt%, Al: 0.5wt%, and P: 7.5wt%; the background loss of the fiber is 24dB / km, the 915nm cladding absorption is 3.8dB / m, and the 1535nm core absorption is 71dB / m; the birefringence coefficient of the fiber is 1.93*10 -4 .

[0099] The preparation steps are the same as those of the comparative example 2.

[0100] Example 3

[0101] Example 3 is obtained based on the fiber preparation process flow of Example 2 by adding a pretreatment step.

[0102] A high laser performance radiation resistant Er-Yb co-doped quartz optical fiber, other fiber parameters are the same as those of Comparative Example 3, except that the prepared Er-Yb co-doped optical fiber has a quartz core of Er-Yb-Al-P co-doped silica glass with a theoretical composition of Er: 0.30wt%, Yb: 4.5wt%, Al: 0.5wt%, and P: 7.5wt%; the background loss of the optical fiber is 31dB / km, the 915nm cladding absorption is 3.8dB / m, and the 1535nm core absorption is 71dB / m; and the birefringence coefficient of the optical fiber is 1.93*10 -4 .

[0103] The preparation steps are the same as those of Comparative Example 3.

[0104] Example 4

[0105] A high laser performance radiation resistant Er-Yb co-doped quartz optical fiber, other fiber parameters are the same as those of Example 2, except that the prepared Er-Yb co-doped optical fiber has a quartz core with a theoretical composition of Er: 0.35wt%, Yb: 5.0wt%, Al: 1.5wt%, and P: 9.0wt%; the background loss of the optical fiber is 18dB / km, the 915nm cladding absorption is 3.4dB / m, and the 1535nm core absorption is 61dB / m; and the birefringence coefficient of the optical fiber is 1.84*10 -4 .

[0106] The preparation steps are the same as those of Comparative Example 2.

[0107] Example 5

[0108] A high laser performance radiation resistant Er-Yb co-doped quartz optical fiber, other fiber parameters are the same as those of Example 2, except that the prepared Er-Yb co-doped optical fiber has a quartz core with a theoretical composition of Er: 0.15wt%, Yb: 3.0wt%, Al: 0.05wt%, and P: 5.0wt%; the background loss of the optical fiber is 23dB / km, the 915nm cladding absorption is 2.2dB / m, and the 1535nm core absorption is 39dB / m; and the birefringence coefficient of the optical fiber is 1.89*10 -4 .

[0109] The preparation steps are the same as those of Comparative Example 2.

[0110] Example 6

[0111] A high laser performance radiation resistant erbium-ytterbium co-doped quartz optical fiber, other fiber parameters are the same as example 2, the difference is that the prepared erbium-ytterbium co-doped optical fiber has a quartz core theoretical composition of: Er: 0.10wt%, Yb: 2.5wt%, Al: 0.5wt%, P: 8.0wt%; the background loss of the optical fiber is 25dB / km, the 915nm cladding absorption is 2.1dB / m, and the 1535nm core absorption is 35dB / m; the birefringence coefficient of the optical fiber is 1.85*10 -4 .

[0112] The preparation steps are the same as those of comparative example 2.

[0113] Table 1: Test results of each comparative example and example

[0114]

[0115] Since the numerical aperture (NA) of the optical fiber itself needs to be controlled to be 0.19, the overall adjustment needs to be made when adjusting the content of the doping elements, and it is impossible to adjust a single element. In the preparation of the traditional radiation resistant erbium-ytterbium co-doped quartz optical fiber, the doping content of the remaining elements is limited due to the need to dope a certain amount of Ce element.

[0116] As shown in Figure 4 , it can be seen from comparative example 2 and comparative example 4 that in the preparation of the traditional radiation resistant erbium-ytterbium co-doped quartz optical fiber, increasing the content of Ce can enhance the radiation resistance of the optical fiber, but will cause the laser efficiency and output power of the optical fiber to decrease.

[0117] As shown in Figure 5 , it can be seen from examples 1 and 2 and comparative examples 1 and 2 that the non-polarization maintaining optical fiber and polarization maintaining optical fiber prepared by the present method have an increase of more than 13% in laser efficiency and output power under the same conditions of the optical fiber amplifier test platform, compared with the non-polarization maintaining optical fiber and polarization maintaining optical fiber prepared by the traditional method, and the radiation resistance has almost no change.

[0118] As shown in Figure 6 , it can be seen from examples 2 and 3 and comparative examples 2 and 3 that although the additional pretreatment step causes the slope efficiency and output power of the optical fiber to decrease to a certain extent, it can greatly improve the radiation resistance of the optical fiber, and the power attenuation of the optical fiber is reduced by more than 60% under the same irradiation dose.

[0119] As shown in Figure 7 , it can be seen from example 3 and comparative example 2 that even if the additional pretreatment step causes the laser performance of the optical fiber to decrease, it is still higher than that of the optical fiber prepared by the traditional method, and the slope efficiency and output power are increased by about 5%, and the power attenuation of the optical fiber is reduced by more than 65% under the same irradiation dose.

[0120] As shown in Table 1, the laser performance of the fiber of the present application is similar to that of the fiber of Comparative Example 1, but the power attenuation of the fiber of the present application is reduced by about 50% under the same irradiation dose. Figure 8 As shown in Table 1, the laser performance of the fiber of the present application is similar to that of the fiber of Comparative Example 1, but the power attenuation of the fiber of the present application is reduced by about 50% under the same irradiation dose.

[0121] Examples 2 and 4 mainly adjust the content of Al doping, and the specific effect is small, and the overall performance is similar.

[0122] As shown in Table 1, the laser performance of the fiber of the present application is similar to that of the fiber of Comparative Example 1, but the power attenuation of the fiber of the present application is reduced by about 50% under the same irradiation dose. Figure 9 As shown in Table 1, the laser performance of the fiber of the present application is similar to that of the fiber of Comparative Example 1, but the power attenuation of the fiber of the present application is reduced by about 50% under the same irradiation dose.

[0123] The present application is not limited to the above-mentioned embodiments, and some improvements can be made by those skilled in the art without departing from the principles of the present application, and these improvements are also considered to be within the scope of protection of the present application. The contents not described in detail in the specification belong to the prior art known to those skilled in the art.

Claims

1. A radiation-resistant erbium-ytterbium co-doped silica optical fiber with high laser performance, characterized in that: The erbium-ytterbium co-doped silica optical fiber comprises a silica core, a silica cladding and a coating layer from the inside out. The quartz fiber core is composed of Er, Yb, Al, and P co-doped silica glass; The quartz cladding is composed of a quartz-based glass material; The coating layer comprises an inner layer of a low-refractive-index coating layer directly coated on the outside of the quartz cladding layer and an outer layer of a high-refractive-index coating layer covering the inner layer.

2. The radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 1, characterized in that: The concentration range of the doping components of the quartz fiber core is: Er: 0.10-0.35wt%, Yb: 2.5-5.0wt%, Al: 0.05-1.5wt%, P: 5.0-9.0wt%.

3. The radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 2, characterized in that: The concentration range of the doping components of the quartz fiber core is: Er: 0.15-0.35wt%, Yb: 3.0-4.5wt%, Al: 0.5-1.5wt%, P: 7.5-9.0wt%.

4. The radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 1, characterized in that: The diameter of the quartz fiber core is 4-40 μm, and the numerical aperture of the quartz fiber core is 0.05-0.

25.

5. The radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 1, characterized in that: The cross-section of the quartz cladding is a regular polygon, and the ratio of the longest diagonal line of the quartz cladding to the diameter of the quartz fiber core is 3 to 35.

6. The radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 1, characterized in that: The quartz cladding includes a pair of axisymmetric stress zones to form a polarization-maintaining fiber structure, and the birefringence coefficient of the quartz fiber at a wavelength of 1550 nm is greater than 1*10 -4 .

7. The radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 6, characterized in that: The stress zone is a circular boron-doped quartz rod, the ratio of the diameter of the boron-doped quartz rod to the diameter of the quartz core is 1.0-9.0, and the ratio of the distance between the center of the boron-doped quartz rod and the center of the quartz core to the diameter of the quartz core is 0.2-8.

0.

8. The radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 1, characterized in that: The inner layer of the low-refractive-index coating layer is made of a fluorine-doped acrylate material; and the outer layer of the high-refractive-index coating layer is made of an acrylate material.

9. The radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 1, characterized in that: The background loss of the quartz optical fiber at a wavelength of 1200 nm is less than 50 dB / km, the cladding absorption at 915 nm is greater than 1.5 dB / m, and the core absorption at 1535 nm is greater than 20 dB / m.

10. The method for preparing a radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to any one of claims 1 to 9, characterized in that: The main steps include: S1: Prepare a preform core rod, where the core part is Er, Yb, Al, and P co-doped silica glass and the tube wall is quartz; S2: Processing preform sleeve; S3: The preform core rod and the preform sleeve are combined and drawn into an optical fiber, and the outside is sequentially coated with an inner layer of a low-refractive-index coating layer and an outer layer of a high-refractive-index coating layer covering the inner layer. Optionally, it also includes: S4: Pre-processing the optical fiber obtained in step S3, including carrier gas treatment and irradiation treatment in sequence.

11. The method for preparing a radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 10, wherein: In step S1 , the preform core rod is formed by using an improved chemical vapor deposition (MCVD) method combined with a solution doping method.

12. The method for preparing a radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 10, wherein: The step S2 includes: processing the cross section of the sleeve into a regular polygon for preparing a non-polarization-maintaining optical fiber.

13. The method for preparing a radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 12, wherein: The regular polygon is a regular octagon.

14. The method for preparing a radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 10, wherein: The step S2 includes: drilling symmetrical circular holes on both sides of the sleeve and inserting boron-doped quartz rods to prepare polarization-maintaining optical fiber.

15. The method for preparing a radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 14, wherein: The ratio of the circular hole diameter to the fiber core diameter is 1.0-9.0, and the ratio of the distance between the circular hole edge and the quartz fiber core edge to the fiber core diameter is 0.2-8.

0.

16. The method for preparing a radiation-resistant Er-Yb co-doped silica optical fiber with high laser performance according to claim 10, wherein: In step S4, the carrier gas treatment includes: the carrier gas environment is a mixed gas of deuterium and helium, wherein the deuterium gas accounts for 20%-100%, the pressure is 4-8 MPa, the temperature is 25-80°C, and the carrier gas treatment time is 12 to 720 hours; the irradiation treatment includes: the irradiation environment is X-ray or gamma ray, the irradiation dose rate is 0.2-50 krad / min, and the total irradiation dose is 20-500 krad.

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