Polymer tube metal coating hollow-core optical fiber prepared through dual-wavelength ultraviolet activation and method

Abstract

The invention discloses a polymer tube metal coating hollow-core optical fiber prepared by dual-wavelength ultraviolet activation and a method thereof, which are characterized in that the surface of a polymer tube is treated by adopting a dual-wavelength ultraviolet activation method so as to enhance the bonding performance between the polymer tube and a metal coating; and the flexible and high-reliability long polymer tube metal coating hollow-core optical fiber applied to different frequency bands is prepared. Compared with the prior art, the dual-wavelength ultraviolet activation method is simple in process, low in cost, small in damage to the surface of the polymer pipe and capable of effectively improving the bonding performance between the silver plating layer and the polymer pipe. Therefore, the transmission stability, reliability and aging resistance of the optical fiber can be improved, and the optical fiber has a great practical prospect. When the long polymer tube is treated, each part can achieve a good pretreatment effect, and consistency and stability in the process of preparing long optical fibers in batches are expected to be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of hollow core optical fiber preparation, in particular to a polymer tube metal-plated hollow core optical fiber prepared by dual-wavelength ultraviolet activation and a method thereof. Background Art

[0002] The transmission of electromagnetic waves is an important technical link in the field of electromagnetic wave research. Wireless transmission in free space is easily affected by environmental factors such as humidity and dust, resulting in poor transmission efficiency, poor transmission stability and reliability. Optical fiber can effectively confine the signal inside the optical fiber structure to achieve efficient, stable and low-loss transmission. The types of optical fibers currently developed include solid core optical fiber, microstructured optical fiber, photonic crystal optical fiber, etc. Among them, metal-coated hollow core optical fiber has the advantages of simple structure, no end face reflection, high damage threshold and low transmission loss. It has broad application prospects in 6G terahertz wired communications, mid- and far-infrared laser transmission, optical fiber sensing and biomedicine.

[0003] The structure of metal-coated hollow-core optical fiber mainly includes a structural tube (metal, glass, polymer tube, etc.) and an inner / outer metal coating. The metal structural tube has good thermal and mechanical properties, but its surface roughness is large and its bending performance is poor; the glass structural tube has a smooth surface and strong bonding with the metal layer, but it is fragile and cannot be bent. The polymer tube has good flexibility and a smooth inner surface, but the bonding force between the polymer tube and the metal coating is an important factor affecting the performance of this type of optical fiber. Therefore, during the preparation process, it is necessary to select a suitable surface activation method to improve the interface bonding force in order to enhance the transmission reliability of the optical fiber.

[0004] Methods for improving the bonding strength between metal coatings and polymers include physical methods such as acid / base chemical etching and plasma activation. Chemical etching of the inner surface of the polymer optical fiber structure tube using acid / base solutions will increase the surface roughness and increase the transmission loss of the optical fiber. Chemical treatment also faces problems such as complex solution composition, residual contamination of the surface by some solution molecules, and affecting the uniformity and density of nucleation growth of the metal coating. The inner surface of the plasma-activated polymer optical fiber structure tube is relatively mild and controllable, which can significantly improve the interfacial bonding strength of the optical fiber. However, plasma activation is difficult to penetrate the polymer tube wall, and it is difficult to diffuse into the middle part of the polymer tube when processing longer capillaries. Therefore, the length of the polymer metal-coated optical fiber developed by the plasma activation method is relatively short. Therefore, it is particularly important to choose an efficient method to treat the surface of the polymer tube to improve the bonding performance between the polymer tube and the metal coating, and to develop a flexible, low-loss metal-coated polymer hollow-core optical fiber with longer length and high transmission reliability. Summary of the invention

[0005] The purpose of the present invention is to provide a polymer tube metal-coated hollow-core optical fiber and method prepared by dual-wavelength ultraviolet activation in response to the shortcomings of the existing polymer tube-based metal-coated hollow-core optical fiber technology. The surface of the polymer tube is treated by dual-wavelength ultraviolet activation, and metal coatings are prepared on the inner and outer surfaces of the polymer tube to obtain a polymer tube metal-coated hollow-core optical fiber. Dual-wavelength ultraviolet activation can achieve surface modification of longer length polymer tubes and improve the bonding performance between interfaces, thereby preparing optical fibers with longer length and higher reliability. The optical fiber prepared by the method described in the present invention has the advantages of good flexibility, low loss, strong transmission reliability and stability, and excellent aging resistance. It has important research value and broad application prospects in the fields of aerospace, infrared / terahertz / microwave sensing and next-generation communications.

[0006] The specific technical solution for achieving the purpose of the present invention is: A method for preparing a polymer tube metal-coated hollow-core optical fiber by dual-wavelength ultraviolet activation, wherein a polymer tube is treated by a dual-wavelength ultraviolet activation process to prepare a polymer tube metal-coated hollow-core optical fiber for use in different transmission frequency bands. The method comprises the following specific steps: Step 1: Treat the surface of the polymer tube using a dual-wavelength UV activation method; Step 2: preparing a metal coating on the outer surface of the polymer tube to obtain a polymer tube metal outer coating hollow core optical fiber; or preparing a metal coating on the inner surface of the polymer tube to obtain a polymer tube metal inner coating hollow core optical fiber; in addition, preparing a dielectric layer on the metal coating surface of the polymer tube metal inner coating hollow core optical fiber to obtain a polymer tube metal / dielectric coating hollow core optical fiber; Wherein: the central wavelengths of the dual-wavelength ultraviolet light for the dual-wavelength ultraviolet activation are 184.9 nm and 253.7 nm respectively; the specific activation process includes: Step 1.1: Clean the surface of the polymer tube using detergent, ethanol and deionized water respectively; Step 1.2: placing the polymer tube in a dual-wavelength ultraviolet irradiation environment for surface activation, and the activation time is 1-45 minutes; wherein, when a metal coating is prepared on the outer surface of the polymer tube, during the activation process of the outer surface of the polymer tube, ozone-containing air is directly introduced into the ultraviolet irradiation environment to enhance the activation effect; when a metal coating is prepared on the inner surface of the polymer tube, during the activation process of the inner surface of the polymer tube, ozone-containing air is introduced into the interior of the polymer tube.

[0007] The metal plating includes chemical liquid deposition, physical vapor deposition and electroplating, and the metal plating materials include silver, copper, gold, aluminum, nickel and platinum.

[0008] The dielectric layer is made of materials including silver iodide, cuprous iodide, cycloolefin polymer, cycloolefin copolymer, polyethylene, polystyrene, polypropylene and polytetrafluoroethylene.

[0009] A polymer tube metal-coated hollow-core optical fiber prepared based on the above method. A polymer tube is used as the structural tube of the hollow-core optical fiber, the polymer tube has a certain transmittance to ultraviolet light, and the polymer includes polypropylene, polyimide, polyethylene, polystyrene, polycarbonate, polytetrafluoroethylene, polymethyl methacrylate, polyethylene terephthalate and cycloolefin copolymer.

[0010] Compared with the prior art, the present invention has the following beneficial technical effects and significant improvements: 1) Compared with chemical methods for treating polymer tubes, the dual-wavelength UV treatment process is simpler, more environmentally friendly and less costly, and has less impact on the surface roughness of polymer tubes; 2) Compared with the plasma method in the physical method to pre-treat the structural tube, the plasma method cannot treat the inner surface of the middle part of the long polymer tube. The dual-wavelength UV activation can achieve high-quality modification effects on the inner / outer surface and different positions of the polymer tube. It is expected to achieve consistency and stability in the process of mass production of long optical fibers; 3) Dual-wavelength UV-activated polymer tube surface improves the bonding performance between the polymer tube and the metal layer, enhances the bending resistance, transmission stability and reliability, aging resistance and temperature resistance of the optical fiber, and increases the service life of the optical fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of the dual-wavelength ultraviolet activation chamber of the present invention. DETAILED DESCRIPTION

[0012] The present invention is further described and illustrated below by taking the preparation of hollow-core optical fibers with different structures and suitable for different frequency bands as an example. Example

[0013] See also Figure 1 , placing the polymer tube in a dual-wavelength ultraviolet activation chamber for treatment, and preparing a silver coating in the structure tube by liquid phase chemical deposition after activation to obtain a polymer tube hollow core optical fiber with an inner silver coating layer. The specific preparation includes the following steps: Step 1: Select a polypropylene tube as the structural tube, with an inner and outer diameter of 4.0 and 4.7 mm respectively and a length of 5.0 m. Use detergent, ethanol and deionized water to clean its surface in turn, and the cleaning time is 5 min each; Step 2: using a dual-wavelength ultraviolet activation method to perform surface treatment on the structural tube, the treatment time is 30 min; when preparing the silver layer on the inner surface of the structural tube, an external ozone generator is used to introduce ozone-containing air into the structural tube during the dual-wavelength ultraviolet activation process, wherein the ozone generator generates 3 g of ozone per hour; the power of the low-pressure mercury lamp used in the dual-wavelength ultraviolet activation process is 100 W; Step 3: Use a peristaltic pump to introduce SnCl2 sensitizing solution into the structural tube for 5 min and deionized water for 1 min; Step 4: Use a peristaltic pump to simultaneously introduce glucose solution and silver ammonia solution into the structural tube, and deposit a silver layer on the inner surface of the structural tube through a silver mirror reaction. The reaction time is 15 min. Step 5: Use a peristaltic pump to pass deionized water into the structural tube for cleaning. The cleaning time is 2 minutes. Step 6: Blow dry air into the structural tube for 4 hours to obtain a hollow-core optical fiber with a silver layer coated in a polypropylene tube.

[0014] The hollow-core optical fiber prepared above has been tested to have a linear loss of less than 2.0 dB / m when transmitting terahertz waves with a frequency of 0.1 THz. In addition, the prepared optical fiber sample still maintains good transmission performance after 200 hours of wet heat aging (60°C, 85 RH%) and 10 vibration sweep tests (sweep frequency range 10-500 Hz). Example

[0015] See also Figure 1 The polymer tube is placed in a dual-wavelength ultraviolet activation chamber for treatment. After activation, a silver layer and a silver iodide reflective film are sequentially prepared on the inner wall of the structure tube by liquid phase chemical deposition to obtain a metal / dielectric coated polymer tube hollow core optical fiber. The specific preparation includes the following steps: Step 1: Select a polyimide tube as the structural tube, with an inner and outer diameter of 2.00 and 2.60 mm, respectively, and a length of 1.0 m. Use detergent, ethanol, and deionized water to clean its surface in turn, with the cleaning time being 5 min each. Step 2: using a dual-wavelength ultraviolet activation method to perform surface treatment on the structural tube, the treatment time is 40 min; when the silver layer is prepared on the inner surface of the structural tube, an external ozone generator is used to introduce ozone-containing air into the structural tube during the dual-wavelength ultraviolet treatment, wherein the ozone generator generates 3 g of ozone per hour; the power of the low-pressure mercury lamp used in the dual-wavelength ultraviolet treatment is 100 W; Step 3: Use a peristaltic pump to introduce SnCl2 sensitizing solution into the structural tube for 5 min and deionized water for 1 min; Step 4: Use a peristaltic pump to simultaneously introduce glucose solution and silver ammonia solution into the structural tube, and deposit a silver layer on the inner surface of the structural tube through a silver mirror reaction. The reaction time is 15 min. Step 5: Use a peristaltic pump to pass an iodine solution with a mass fraction of 10 g / L into the optical fiber with the inner silver-plated layer, generate a silver iodide reflective film on the surface of the inner silver-plated layer through an iodination reaction, and then pass ethanol to clean it for 2 minutes; Step 6: Blow dry air into the structural tube for 2 h to obtain a metal / dielectric coated hollow core optical fiber with Ag / AgI layer plated inside the polyimide tube.

[0016] The metal / dielectric coated polymer tube hollow core optical fiber prepared above was tested and found that when transmitting infrared waves with a wavelength of 10.6 μm, the linear transmission loss was less than 1.0 dB / m. Example

[0017] See also Figure 1 The polymer tube is placed in a dual-wavelength ultraviolet activation chamber for treatment. After activation, a copper layer is deposited on the outer surface of the structure tube by electroplating to obtain a polymer tube outer copper-plated hollow-core optical fiber. The specific preparation includes the following steps: Step 1: Select a polypropylene tube as the structural tube, with an inner and outer diameter of 5.00 mm and 5.70 mm, respectively, and a length of 0.6 m. Use detergent, ethanol, and deionized water to clean its surface, with a cleaning time of 5 min each. Step 2: using a dual-wavelength ultraviolet method to perform surface treatment on the structural tube, the treatment time is 20 min; the power of the low-pressure mercury lamp used in the dual-wavelength ultraviolet treatment is 100 W; Step 3: Build an outer sleeve outside the structural tube. The inner diameter of the outer sleeve is 10.0 mm. The upper and lower ends of the structural tube are sealed and provided with support rings to prevent the structural tube from fitting with the outer sleeve. Step 4: Use a peristaltic pump to introduce SnCl2 sensitizing solution into the outer tube for 5 min and deionized water for 1 min; Step 5: Use a peristaltic pump to simultaneously introduce glucose solution and silver ammonia solution into the outer tube, and deposit a silver layer on the inner surface of the structural tube through a silver mirror reaction. The reaction time is 5 minutes; Step 6: Use a peristaltic pump to pass deionized water into the outer sleeve for cleaning. The cleaning time is 2 minutes. Step 7: Take out the structural tube with silver electrodes from the outer sleeve and place it in an electrolyte. The electrolyte for electroplating copper is composed of basic copper carbonate, citric acid, potassium sodium tartrate and sodium bicarbonate. The electroplating time is 60 minutes. After the electroplating is completed, the surface is cleaned with deionized water and then blown dry to obtain a hollow-core optical fiber with a copper layer plated on the outside of the polypropylene tube.

[0018] The above-prepared polymer tube copper-plated hollow-core optical fiber has been tested to have a linear loss of less than 2.0 dB / m when transmitting terahertz waves with a frequency of 0.1 THz. After 10 vibration cycle tests (sweep frequency range 10-500 Hz), the transmission loss of the waveguide remains basically unchanged.

[0019] The present invention greatly improves the bonding strength between the polymer tube and the metal layer by performing dual-wavelength ultraviolet activation on the surface of the polymer tube, and prepares a hollow-core optical fiber with a silver-plated layer inside the polymer tube by a chemical liquid phase lamination method. On the basis of the hollow-core optical fiber with a silver-plated layer inside the polymer tube, a silver iodide reflective film is generated on the inner silver-plated layer by an iodination reaction to prepare an Ag / AgI-plated polymer tube hollow-core optical fiber. A metal copper-plated layer is deposited on the outer surface of the polymer tube by an electroplating method to prepare a hollow-core optical fiber with a metal-plated layer outside the polymer tube. The present invention greatly improves the bonding strength between the polymer tube and the metal coating by performing dual-wavelength ultraviolet activation on the surface of the polymer tube, and improves the transmission stability, reliability and aging resistance of the optical fiber. When processing a relatively long polymer tube, each part can achieve a good pretreatment effect, and it is expected to achieve consistency and stability in the process of mass preparation of long optical fibers.

[0020] The above is only a further explanation of the present invention and is not intended to limit the present invention. Any equivalent implementation of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A method for preparing a polymer tube metal-coated hollow-core optical fiber by dual-wavelength ultraviolet activation, characterized in that: The method comprises the following specific steps: Step 1: Treat the outer surface or inner surface of the polymer tube using a dual-wavelength ultraviolet activation method; Step 2: preparing a metal coating on the outer surface of the polymer tube to obtain a polymer tube metal outer coating hollow core optical fiber; or preparing a metal coating on the inner surface of the polymer tube to obtain a polymer tube metal inner coating hollow core optical fiber; in addition, preparing a dielectric layer on the metal coating surface of the polymer tube metal inner coating hollow core optical fiber to obtain a polymer tube metal / dielectric coating hollow core optical fiber; Wherein: the central wavelengths of the dual-wavelength ultraviolet light for the dual-wavelength ultraviolet activation are 184.9 nm and 253.7 nm respectively; the specific activation process includes: Step 1.1: Clean the surface of the polymer tube using detergent, ethanol and deionized water respectively; Step 1.2: placing the polymer tube in a dual-wavelength ultraviolet irradiation environment for surface activation, the activation time is 1-45 minutes; wherein, during the activation process of the outer surface of the polymer tube, ozone-containing air is directly introduced into the ultraviolet irradiation environment; during the activation process of the inner surface of the polymer tube, ozone-containing air is introduced into the interior of the polymer tube.

2. The method according to claim 1, characterized in that The metal plating includes chemical liquid deposition, physical vapor deposition and electroplating, and the metal plating materials include silver, copper, gold, aluminum, nickel and platinum.

3. The method according to claim 1, characterized in that The dielectric layer is made of materials including silver iodide, cuprous iodide, cycloolefin polymer, cycloolefin copolymer, polyethylene, polystyrene, polypropylene and polytetrafluoroethylene.

4. A polymer tube metal-coated hollow-core optical fiber prepared by the method according to claim 1.

5. The polymer tube metal-coated hollow core optical fiber according to claim 4, characterized in that: A polymer tube is used as the structural tube of the hollow core optical fiber. The polymer tube is transparent to ultraviolet light, and the polymer includes polypropylene, polyimide, polyethylene, polystyrene, polycarbonate, polytetrafluoroethylene, polymethyl methacrylate, polyethylene terephthalate and cycloolefin copolymer.

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