Controllably loaded gas resistant radiation preserving gain optical fiber

Abstract

The application discloses a controllable gas-loaded anti-radiation polarization maintaining gain optical fiber, which has a cross-section structure including a high-refraction coating layer, a low-refraction coating layer, a fiber cladding, a gain fiber core, a hollow stress area and glass microspheres filled in the hollow holes of the stress area. The optical fiber can realize controllable gas loading according to the change of visible light power, so as to improve the anti-radiation performance of the polarization maintaining gain optical fiber. The principle is that the hollow glass microspheres doped with transition metals have a photo-induced vibration effect, and the glass microspheres irradiated by visible light form gas diffusion channels on the walls of the glass microspheres. The controllable gas loading of the glass microspheres can be realized under the conditions of pressurization or normal pressure. The anti-radiation capacity of the optical fiber is improved by controlling the gas loading, and the gas preservation life of the optical fiber is prolonged by controlling the gas release. The application can significantly improve the anti-radiation performance and the gas preservation life of the polarization maintaining gain optical fiber, and can fill the related field blank of the high-reliability long-life space polarization maintaining gain optical fiber, so as to provide a powerful guarantee for the execution of space tasks.

Description

TECHNICAL FIELD

[0001] The application relates to the field of laser technology and discloses a controllable anti-radiation polarization-maintaining gain optical fiber with gas loading and releasing, glass microspheres in the optical fiber can open gas diffusion channels under visible light excitation, so that the controllable gas loading and releasing of the optical fiber can be realized under pressurized / normal pressure conditions, the anti-radiation characteristics and gas preservation life of the optical fiber can be significantly improved, and the application can fill the blank in the related field of high-reliability long-life polarization-maintaining gain optical fibers for space use. BACKGROUND

[0002] The polarization-maintaining gain optical fiber is a core device for outputting high-power, narrow-linewidth and high-polarization-extinction-ratio laser, but in the irradiation environment, the performance of the polarization-maintaining gain optical fiber gradually deteriorates with the accumulation of irradiation dose, such as the reduction of output power and polarization extinction ratio, the increase of optical fiber temperature and the like, and even the burning of the optical fiber laser, so it is of great research value to improve the anti-radiation characteristics of the polarization-maintaining gain optical fiber.

[0003] The gas loading on the gain optical fiber can effectively improve the anti-radiation characteristics, and common gas types include hydrogen, deuterium, oxygen and the like, and the current gas loading scheme mainly has the following disadvantages: the high-pressure environment can effectively load the gas in the optical fiber, but in the normal pressure environment, the gas in the optical fiber will gradually escape over time, and research shows that the gas loading amount will decrease to zero after three months, at which time the gain optical fiber has completely lost the anti-radiation capability, so it is necessary to design a microstructure for storing the gas in the optical fiber to improve the gas preservation life; the glass microsphere structure can effectively store the gas, but the temperature for loading and releasing the gas needs to be above 300 DEG C, and the coating layer of the optical fiber will be damaged at this high temperature, so it has great application prospect to realize the loading and releasing of the glass microspheres at normal temperature. SUMMARY

[0004] The application solves the technical problem of overcoming the disadvantages of the prior art and providing a controllable anti-radiation polarization-maintaining gain optical fiber with gas loading and releasing, which can significantly improve the anti-radiation characteristics and gas preservation life of the polarization-maintaining gain optical fiber, and fill the blank in the related field of high-reliability long-life polarization-maintaining gain optical fibers for space use, thereby providing strong guarantee for space missions.

[0005] The technical scheme of the application is as follows: a controllable anti-radiation polarization-maintaining gain optical fiber with gas loading and releasing comprises a high-refraction coating layer, a low-refraction coating layer, an optical fiber cladding and a gain core which are covered layer by layer from outside to inside; hollow stress zones are symmetrically distributed on both sides of the gain core; glass microspheres serving as carriers for loading and releasing the gas are filled in the hollow holes of the hollow stress zones; the high-refraction coating layer has wear-resistant properties and is used for protecting the optical fiber; the low-refraction coating layer is used for realizing the total reflection propagation of pump light; the cladding is used for realizing the total reflection propagation of polarized laser; the gain core is used for generating and transmitting polarization-maintained laser; and the hollow stress zones are used for providing the stress required by laser polarization propagation.

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

[0007] The high-refractive coating layer is composed of polyacrylate and polyimide, has a tensile strength greater than or equal to 10 MPa, and has a refractive index equal to 1.55±0.1 in the 1-micron wave band.

[0008] The low-refractive coating layer is composed of polyacrylate and polyimide, has a tensile strength greater than or equal to 9 MPa, and has a refractive index equal to 1.35±0.1 in the 1-micron wave band.

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

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

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

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

[0013] The response wave 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 wave band is 350-700 nm.

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

[0015] (1) The size of the hollow hole of the stress region can be adjusted, the size and composition of the glass microspheres can be adjusted, and the related parameters can be flexibly designed to meet various application requirements. Under the premise of meeting the polarization maintaining performance, different hollow hole sizes of boron-doped quartz rods 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 demand of the optical fiber for the carrier gas in different application scenarios; the size and composition of the glass microspheres can be adjusted, the appropriate size of the glass microspheres is selected to match the size of the hollow hole of the stress region, and the doping composition of the glass microspheres is adjusted to adjust the response wave band of the glass microspheres to visible light, so that the response wave band can be flexibly adjusted according to the working wave band of the laser.

[0016] (2) The controllable carrier / gas release in the application only needs to pass light and pressurize to complete, without high-temperature environment, avoiding the safety hazard of dangerous gases such as hydrogen at high temperature, so that the types of loadable gases are various, and the types of carrier gases can be flexibly adjusted according to actual needs.

[0017] (3) The glass microspheres in the application can repeatedly load and release gas, and the economy of the optical fiber is better. The gas retention life of the glass microspheres with excellent performance can be more than 1 year, and there is no gas leakage problem after being irradiated by rays, and only visible light of a specific waveband and high temperature are sensitive, which is suitable for irradiation environment; the glass microspheres can repeatedly load and release gas, and the optical fiber also has the ability of repeated use, and the economy is better. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 A cross-sectional schematic view of the controllable carrier / gas release anti-radiation polarization maintaining gain optical fiber provided by the application is shown.

[0019] Figure 2 The left side is the controllable carrier gas process of the optical fiber in the air bed, and the right side is the controllable gas release process of the optical fiber in actual application. DETAILED DESCRIPTION

[0020] As shown in Figure 1 A controllable carrier / gas release anti-radiation polarization maintaining gain optical fiber, including high-refractive coating layer 101, low-refractive coating layer 102, optical fiber cladding 103, gain fiber core 104, which are covered layer by layer from outside to inside; there are hollow stress zones 105 symmetrically distributed on both sides of the gain fiber core 104; glass microspheres 106 are filled in the hollow holes of the hollow stress zones 105 as carriers for loading and releasing gas; wherein the high-refractive coating layer 101 has wear-resistant properties for protecting 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; the gain fiber core 104 is used to generate and transmit polarization maintaining laser; the hollow stress zone 105 is used to provide the stress required for laser polarization propagation.

[0021] After parameter design and sample preparation, the optical fiber product of 20 / 400 μm specification is made, and each parameter is as follows: the refractive index of high-refraction coating layer is 1.55 at 1 μm wave band, the tensile strength is 10 MPa, and the thickness is 30 μm; the refractive index of low-refraction coating layer is 1.38 at 1 μm wave band, the tensile strength is 9.5 MPa, and the thickness is 40 μm; the refractive index of fiber cladding drawn from a quartz rod is 1.46 at 1 μm wave band, the diameter is 400 μm, the numerical aperture between the low-refraction coating layer and the fiber cladding is about 0.49, and the common 976 nm pumping light propagation can be met; the gain core is deposited by Yb, Al and P doped SiO2, the refractive index is 1.4614 at 1 μm wave band, the diameter is 20 μm, the numerical aperture between the fiber cladding and the gain core is about 0.064, and the 1064 nm polarized laser propagation can be met; the hollow stress region is drawn by a boron-doped hollow quartz rod, the outer diameter is 105 μm, and the hollow hole diameter is 30 μm; and the glass microsphere is made of titanium-doped alkali borosilicate glass, the response wave band of the glass microsphere to visible light is 400-600 μm, the microsphere diameter is distributed between 10-28 μm, the microsphere wall thickness is less than 5 μm, and the microsphere is filled into the hollow hole of the stress region by air flow after the optical fiber is drawn.

[0022] Firstly, the controllable carrier gas process is carried out, the optical fiber product with a length of 13 m is fused with the tail fiber of a 532 nm light source, and then the optical fiber is placed in a deuterium filling bed; the 532 nm light source is turned on, the glass microsphere is excited by light to open the gas diffusion channel, deuterium is filled into the filling bed and gradually pressurized, and the carrier gas content in the optical fiber gradually increases with the gradual increase of the gas pressure; after the carrier gas content in the optical fiber reaches the designed value, the 532 nm light source is turned off, and the gas diffusion channel of the glass microsphere is closed, a small amount of deuterium is released from the glass microsphere in this process, and after the carrier gas content in the optical fiber is stable, the remaining carrier gas in the filling bed is depressurized and emptied. Figure 2 As shown in the left side of the figure.

[0023] Then, the controllable gas release process is carried out, the optical fiber after being filled with carrier gas is used as a gain optical fiber, an anti-radiation polarization maintaining optical fiber laser is made, and the laser is placed in a radiation environment for work, and the output power can reach 1 kW; after a long time of work, the output power of the laser decreases by about 20%, indicating that part of the carrier gas in the optical fiber escapes; the 532 nm light source in the laser is turned on, the glass microsphere in the optical fiber is excited by light to open the gas diffusion channel, and the deuterium stored in the microsphere slowly escapes and diffuses in the optical fiber, and after the 532 nm light source is turned off, the output power is recovered to 0.92 kW when the light is turned on again, indicating that the anti-radiation performance of the optical fiber is restored, and the gas preservation life of the glass microsphere can reach more than one year. At this time, the controllable gas release process of the optical fiber in the application is completed, as shown in the right side of the figure. Figure 2 As shown in the left side of the figure.

[0024] The test results of the embodiment show that the application can realize controllable loading and releasing of gas according to the change of visible light power, so as to improve the anti-radiation performance and gas preservation life of the polarization maintaining gain optical fiber, and finally enhance the application performance of the polarization maintaining fiber laser in the radiation environment. The parameter design of the application is flexible and reusable, has great application prospect, can fill the related field blank of the high-reliability long-life polarization maintaining gain optical fiber in space, and provides strong guarantee for performing space tasks.

[0025] Although the application has been disclosed with the above preferred embodiments, it is not intended to limit the application, and any person skilled in the art can make possible changes and modifications to the technical solutions of the application by using the disclosed methods and technical contents without departing from the spirit and scope of the application. Therefore, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the application, which does not depart from the technical solutions of the application, belongs to the protection scope of the technical solutions of the application.

Claims

1. A controllably loaded, radiation resistant, polarization maintaining gain fiber, characterized by: The high-refractive coating layer (101), the low-refractive coating layer (102), the fiber cladding (103), and the gain core (104) are sequentially coated from outside to inside; the hollow stress region (105) is symmetrically distributed on both sides of the gain core (104); the glass microspheres (106) are filled in the hollow holes of the hollow stress region (105) as carriers for releasing gas; the high-refractive coating layer (101) has wear-resistant property and is used for protecting the optical fiber; the low-refractive coating layer (102) is used for realizing total reflection propagation of pump light; the fiber cladding (103) is used for realizing total reflection propagation of polarized laser; the gain core (104) is used for generating and transmitting polarized laser; and the hollow stress region (105) is used for providing stress required by laser polarization propagation.

2. The controllable-clad-gas-loaded radiation resistant gain fiber according to claim 1, wherein: The refractive index of the low-refractive coating layer (102) is lower than that of the fiber cladding (103); and the refractive index of the fiber cladding (103) is lower than that of the gain core (104).

3. The controllable-clad-gas-loaded radiation resistant gain fiber according to claim 1, wherein: The high-refractive coating layer (101) is composed of polyacrylate and polyimide, the tensile strength is greater than or equal to 10 MPa, and the refractive index in the 1 μm band is 1.55±0.

1.

4. The controllable-clad-gas-loaded radiation resistant gain fiber according to claim 1, wherein: The low-refractive coating layer (102) is composed of polyacrylate and polyimide, the tensile strength is greater than or equal to 9 MPa, and the refractive index in the 1 μm band is 1.35±0.

1.

5. The controllable-clad-gas-loaded radiation resistant gain fiber according to claim 1, wherein: The fiber cladding (103) is composed of quartz material, the refractive index is adjusted by doping F and Ge elements, the refractive index in the 1 μm band is 1.46±0.02, and the fiber cladding (103) realizes total reflection propagation of pump light on the interface with the low-refractive coating layer (102).

6. The controllable-clad-gas-loaded radiation resistant gain fiber according to claim 1, wherein: The gain core (104) is composed of quartz material and doped with multiple elements, including Yb, Tm, Ho, Er, Nd, Al, P, Ce, and F, the refractive index in the 1 μm band is 1.4615±0.02, and the gain core (104) realizes total reflection propagation of polarized laser on the interface with the fiber cladding (103).

7. The controllable-clad-gas-loaded radiation resistant gain fiber according to claim 1, wherein: The material of the hollow stress region (105) is a hollow boron-doped quartz rod, the outer diameter of the hollow stress region is 1 / 4 of the diameter of the fiber cladding (103), and the diameter of the hollow hole of the hollow stress region (105) is not greater than 1 / 3 of the outer diameter of the hollow stress region (105).

8. The controllable-clad-gas-loaded radiation resistant gain fiber according to claim 1, wherein: The glass microspheres (106) are hollow structures, the outer diameter is less than or equal to 60 μm, the wall thickness is less than or equal to 5 μm, and the material is transition metal-doped alkali borosilicate glass.

9. A controllable-clad-gas-filled radiation-resistant gain fiber according to claim 8, characterized in that: The response band of the glass microspheres (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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