Anti-irradiation polarization-maintaining gain optical fiber capable of controlling load and gas release

Abstract

The invention relates to an anti-radiation polarization-maintaining gain optical fiber capable of controlling loading and outgassing. The cross section structure of the anti-radiation polarization-maintaining gain optical fiber is divided into a high-folding coating layer, a low-folding coating layer, an optical fiber cladding layer, a gain fiber core, a hollow stress area and glass microspheres filled in hollow holes of the stress area. The optical fiber realizes controllable gas loading and releasing according to the change of visible light power so as to improve the radiation resistance of the polarization-maintaining gain optical fiber, and the principle is as follows: transition metal doped hollow glass microspheres have a light-induced vibration effect, a gas diffusion channel is formed on the wall of the glass microspheres irradiated by visible light, and the light-induced vibration effect is enhanced. Controllable gas loading and releasing of the glass microspheres can be achieved under the pressurization / normal pressure condition, the anti-irradiation capacity of the optical fiber is improved by conducting controllable gas loading on the optical fiber, and the gas retaining life of the optical fiber is prolonged by controlling the gas release. According to the invention, the anti-radiation characteristic and the gas retention life of the polarization-maintaining gain optical fiber can be obviously enhanced, the blank of the high-reliability long-life space polarization-maintaining gain optical fiber in the related field can be filled up, and a powerful guarantee is provided for executing space tasks.

Description

Technical Field

[0001] The present invention relates to the field of laser technology, and demonstrates a radiation-resistant polarization-maintaining gain optical fiber with controllable gas loading and release. The glass microspheres in the optical fiber can open gas diffusion channels under the stimulation of visible light. Therefore, controllable gas loading / release of the optical fiber can be achieved under pressurized / normal pressure conditions, which can significantly enhance its radiation resistance and gas retention life. The invention can fill the gap in the related field of high-reliability and long-life polarization-maintaining gain optical fibers for space use. Background Art

[0002] Polarization-maintaining gain fiber is a core device for outputting high-power, narrow-linewidth, and high polarization extinction ratio lasers. However, in an irradiated environment, many properties of polarization-maintaining gain fiber gradually deteriorate with the accumulation of irradiation dose, such as reduced output power and polarization extinction ratio, increased fiber temperature, and even causing the fiber laser to burn out. Therefore, improving the radiation resistance of polarization-maintaining gain fiber has important research value.

[0003] Carrier gas loading for gain optical fiber can effectively improve its radiation resistance. Common types of carrier gases include hydrogen, deuterium, oxygen, etc. The current carrier gas scheme has the following main shortcomings: high-pressure environment can effectively load gas into the optical fiber, but under normal pressure environment, the carrier gas in the optical fiber will gradually escape over time. Studies have found that its carrier gas volume will drop to zero after three months. At this time, the gain optical fiber has completely lost its radiation resistance. Therefore, it is necessary to design a gas storage microstructure in the optical fiber to increase its gas retention life; the glass microsphere structure can effectively store gas, but the loading / release temperature needs to reach above 300°C, and the optical fiber coating will be damaged at this high temperature. Therefore, the loading / release of glass microspheres at room temperature has great application prospects. Summary of the invention

[0004] The technical problem solved by the present invention is: to overcome the shortcomings of the existing solutions and provide a radiation-resistant polarization-maintaining gain optical fiber with controllable gas loading and release, which can significantly improve the radiation-resistant properties and gas retention life of the polarization-maintaining gain optical fiber, fill the gap in the related field of high-reliability and long-life polarization-maintaining gain optical fiber for space, and provide strong guarantee for the execution of space missions.

[0005] The technical solution of the present invention is: a controllable gas-carrying and radiation-resistant polarization-maintaining gain optical fiber, comprising a high-refractive coating layer, a low-refractive coating layer, an optical fiber cladding, and a gain core, which are coated layer by layer from the outside to the inside; hollow stress areas are symmetrically distributed on both sides of the gain core; glass microspheres are filled in the hollow holes of the hollow stress areas as carriers of the released gas; wherein the high-refractive coating layer has wear-resistant properties and is used to protect the optical fiber; the low-refractive coating layer is used to achieve total reflection propagation of pump light; the cladding is used to achieve total reflection propagation of polarized laser; the gain core is used to generate and transmit polarization-maintaining laser; and the hollow stress area is used to provide the stress required for laser polarization propagation.

[0006] The refractive index of the low-refractive coating layer is lower than that of the cladding; and the refractive index of the cladding is lower than that of the gain core.

[0007] The high-refractive coating layer is composed of polyacrylate and polyimide, has a tensile strength of ≥10Mpa, and a refractive index of 1.55±0.1 in the 1μm waveband.

[0008] The low-refractive coating layer is composed of polyacrylate and polyimide, has a tensile strength of ≥9Mpa, and a refractive index of 1.35±0.1 in the 1μm waveband.

[0009] The optical fiber cladding is composed of quartz material, and its refractive index is adjusted by doping F and Ge elements. The refractive index in the 1 μm band is 1.46±0.02. The optical fiber cladding realizes total reflection propagation of pump light at the interface with the low-refractive coating layer.

[0010] The gain fiber core is composed of quartz material and doped with multiple elements, including: Yb, Tm, Ho, Er, Nd, Al, P, Ce, F, and the refractive index in the 1μm band is 1.4615±0.02; the gain fiber core realizes total reflection propagation of polarized laser at the interface with the optical fiber cladding.

[0011] The material of the hollow stress zone is a hollow boron-doped quartz rod, the outer diameter of the hollow stress zone is 1 / 4 of the diameter of the optical fiber cladding, and the diameter of the hollow hole of the hollow stress zone is not greater than 1 / 3 of the outer diameter of the hollow stress zone.

[0012] The glass microspheres are hollow structures with an outer diameter of ≤60 μm and a wall thickness of ≤5 μm, and are made of transition metal-doped alkali borosilicate glass.

[0013] The response band of the glass microspheres to visible light is adjusted by adjusting the doping concentration of transition metals Fe, Co, Ni, and Ti, so that the final response band is 350 to 700 nm.

[0014] Compared with the prior art, the present invention has the following beneficial effects:

[0015] (1) In the present invention, the size of the hollow hole in the stress zone is adjustable, the size and composition of the glass microspheres are adjustable, and the relevant parameters can be flexibly designed to meet a variety of application requirements. Under the premise of meeting the polarization-maintaining performance, boron-doped quartz rods with different hollow hole sizes can be selected to prepare the optical fiber, and the capacity of the glass microspheres in the optical fiber can be changed to meet the differentiated requirements of the optical fiber for the amount of carrier gas in different application scenarios; the size and composition of the glass microspheres are adjustable, and the glass microspheres of appropriate sizes are selected to match the size of the hollow holes in the stress zone, and the doping composition of the glass microspheres is adjusted to adjust its response band to visible light, and its response band can be flexibly adjusted according to the working band of the laser.

[0016] (2) The controllable gas loading / release in the present invention can be completed by only passing light and pressurizing, without the need for a high temperature environment, thus avoiding the potential safety hazards of dangerous gases such as hydrogen at high temperatures. Therefore, a variety of gases can be loaded, and the type of carrier gas can be flexibly adjusted according to actual needs.

[0017] (3) The glass microspheres in the present invention can repeatedly load / release gas, and the economical efficiency of this type of optical fiber is good. The gas retention life of glass microspheres with excellent performance can reach more than 1 year, and there is no leakage problem after being irradiated by radiation. They are only sensitive to visible light in a specific band and high temperature, and are suitable for irradiation environments; glass microspheres can repeatedly load / release gas, and this type of optical fiber also has the ability to be reused, which is economical. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic cross-sectional view of the radiation-resistant polarization-maintaining gain optical fiber with controllable gas-carrying and gas-release provided by the present invention;

[0019] Figure 2 The left side shows the controllable gas-carrying process of the optical fiber in the air-filled bed, and the right side shows the controlled gas-releasing process of the optical fiber in actual application. DETAILED DESCRIPTION

[0020] like Figure 1 As shown, a controllable gas-carrying and radiation-resistant polarization-maintaining gain optical fiber comprises a high-refractive coating layer 101, a low-refractive coating layer 102, an optical fiber cladding 103, and a gain core 104, which are coated layer by layer from the outside to the inside; hollow stress regions 105 are symmetrically distributed on both sides of the gain core 104; glass microspheres 106 are filled in the hollow holes of the hollow stress regions 105 as carriers of the released gas; wherein the high-refractive coating layer 101 has a wear-resistant property and is used to protect the optical fiber; the low-refractive coating layer 102 is used to realize the total reflection propagation of the pump light; the cladding 103 is used to realize the total reflection propagation of the polarized laser; the gain core 104 is used to generate and transmit the polarization-maintaining laser; the hollow stress region 105 is used to provide the stress required for the polarization propagation of the laser.

[0021] After parameter design and sample preparation, 20 / 400μm optical fiber products were made. The parameters are as follows: the refractive index of the high-refractive coating layer in the 1μm band is 1.55, the tensile strength is 10Mpa, and the thickness is 30μm; the refractive index of the low-refractive coating layer in the 1μm band is 1.38, the tensile strength is 9.5Mpa, and the thickness is 40μm; the optical fiber cladding is drawn from a quartz rod, with a refractive index of 1.46 in the 1μm band and a diameter of 400μm. The numerical aperture between the low-refractive coating and the fiber cladding is about 0.49, which can meet the propagation of common 976nm pump light; the gain core is composed of Yb, Al, It is made of P-doped SiO2 deposited, with a refractive index of 1.4614 in the 1μm band, a diameter of 20μm, and a numerical aperture of about 0.064 between the optical fiber cladding, which can meet the propagation of 1064nm polarized laser; the hollow stress zone is drawn from a boron-doped hollow quartz rod, with an outer diameter of 105μm and a hollow hole diameter of 30μm; the glass microspheres are made of titanium-doped alkali borosilicate glass, with a response band of 400 to 600μm to visible light, a microsphere diameter ranging from 10 to 28μm, and a microsphere wall thickness of <5μm. After the optical fiber is drawn, the hollow hole in the stress zone is filled by airflow.

[0022] First, a controllable carrier gas process is performed. A 13m-long optical fiber product is fused with the pigtail of a 532nm light source, and then the optical fiber is placed in a deuterium gas-filled bed. The 532nm light source is turned on, and the glass microspheres are stimulated by light to open the gas diffusion channel. Deuterium gas is filled into the gas-filled bed and gradually pressurized. As the gas pressure gradually increases, the carrier gas content in the optical fiber gradually increases. After the carrier gas content in the optical fiber reaches the designed value, the 532nm light source is turned off, and the gas diffusion channel of the glass microspheres is closed. During this process, a small amount of deuterium escapes from the glass microspheres. After the carrier gas content in the optical fiber stabilizes, the remaining carrier gas in the gas-filled bed is depressurized and emptied. At this point, the optical fiber controllable carrier gas process of the present invention is completed. Figure 2 Shown on the left.

[0023] After that, a controlled gas release process is carried out, and the optical fiber after the carrier gas is used as the gain fiber to make an resistant radiation polarization-maintaining fiber laser, and the laser is placed in an irradiation environment for operation, and the output power can reach 1kW; after working for a long time, the output power of the laser drops by about 20%, indicating that part of the carrier gas in the optical fiber has escaped; the 532nm light source in the laser is turned on, and the glass microspheres in the optical fiber open the gas diffusion channel after being stimulated by light, and the deuterium stored in the microspheres slowly escapes and diffuses inside the optical fiber. After turning off the 532nm light source, the light is turned on again and it is found that the output power is restored to 0.92kW, indicating that the radiation resistance of this type of optical fiber has been restored, and the gas retention life of the glass microspheres can reach more than 1 year. At this point, the optical fiber controlled gas release process of the present invention is completed. Figure 2 Shown on the right.

[0024] The test results of this embodiment show that the present invention can realize controllable gas loading / release according to the change of visible light power, thereby improving the radiation resistance and gas retention life of the polarization-maintaining gain fiber, and finally enhancing the application performance of the polarization-maintaining fiber laser in the irradiated environment. The parameter design of the present invention is flexible and reusable, with great application prospects, which can fill the gap in the related fields of high-reliability and long-life polarization-maintaining gain fiber for space, and provide strong guarantee for the execution of space missions.

[0025] Although the present invention has been disclosed as above in the form of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications to the technical solution of the present invention by using the methods and technical contents disclosed above without departing from the spirit and scope of the present invention. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A radiation-resistant polarization-maintaining gain optical fiber with controllable gas release, characterized in that: The invention comprises a high-refractive coating layer (101), a low-refractive coating layer (102), an optical fiber cladding (103), and a gain core (104) which are coated layer by layer from the outside to the inside; hollow stress regions (105) are symmetrically distributed on both sides of the gain core (104); glass microspheres (106) are filled in the hollow holes of the hollow stress regions (105) as carriers for releasing gas; wherein the high-refractive coating layer (101) has a wear-resistant property and is used to protect the optical fiber; the low-refractive coating layer (102) is used to realize the total reflection propagation of pump light; the cladding (103) is used to realize the total reflection propagation of polarized laser light; the gain core (104) is used to generate and transmit polarization-maintaining laser light; and the hollow stress region (105) is used to provide the stress required for the polarization propagation of laser light.

2. The radiation-resistant polarization-maintaining gain optical fiber with controllable gas release according to claim 1, characterized in that: The refractive index of the low-refractive coating layer (102) is lower than that of the cladding (103); and the refractive index of the cladding (103) is lower than that of the gain core (104).

3. The controllable gas-carrying and release-radiation-resistant polarization-maintaining gain optical fiber according to claim 1, characterized in that: The high-refractive coating layer (101) is composed of polyacrylate and polyimide, has a tensile strength of ≥10Mpa, and a refractive index of 1.55±0.1 in the 1μm waveband.

4. The radiation-resistant polarization-maintaining gain optical fiber with controllable gas release according to claim 1, characterized in that: The low-refractive coating layer (102) is composed of polyacrylate and polyimide, has a tensile strength of ≥9Mpa, and a refractive index of 1.35±0.1 in the 1μm waveband.

5. The radiation-resistant polarization-maintaining gain optical fiber with controllable gas release according to claim 1, characterized in that: The optical fiber cladding (103) is made of quartz material, and its refractive index is adjusted by doping F and Ge elements, and the refractive index in the 1 μm band is 1.46±0.

02. The optical fiber cladding (103) realizes total reflection propagation of pump light at the interface with the low-refractive coating layer (102).

6. The radiation-resistant polarization-maintaining gain optical fiber with controllable gas release according to claim 1, characterized in that: The gain fiber core (104) is made of quartz material and doped with multiple elements, including: Yb, Tm, Ho, Er, Nd, Al, P, Ce, F, and has a refractive index of 1.4615±0.02 in the 1 μm band; the gain fiber core (104) realizes total reflection propagation of polarized laser light at the interface with the optical fiber cladding (103).

7. The radiation-resistant polarization-maintaining gain optical fiber with controllable gas release according to claim 1, characterized in that: The material of the hollow stress zone (105) is a hollow boron-doped quartz rod, the outer diameter of the hollow stress zone is 1 / 4 of the diameter of the optical fiber cladding (103), and the diameter of the hollow hole of the hollow stress zone (105) is not greater than 1 / 3 of the outer diameter of the hollow stress zone (105).

8. The controllable gas-carrying and -released radiation-resistant polarization-maintaining gain optical fiber according to claim 1, characterized in that: The glass microsphere (106) is a hollow structure with an outer diameter of ≤60 μm and a wall thickness of ≤5 μm, and is made of transition metal-doped alkali borosilicate glass.

9. The controllable gas-carrying and release-radiation-resistant polarization-maintaining gain optical fiber according to claim 8, characterized in that: The response band of the glass microsphere (106) to visible light is adjusted by adjusting the doping concentration of transition metals Fe, Co, Ni and Ti, so that the final response band is 350-700 nm.

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