CN103553319B - A kind of method that uses nanoassemble fabrication techniques rare-earth doped optical fibre - Google Patents

Abstract

The invention belongs to the field of optical fiber technology, and in particular relates to a method for making rare earth-doped optical fiber using nanometer self-assembly technology. The method of the invention utilizes the nano assembly technology to make the rare earth ions evenly distributed in the optical fiber, and reduces the reduction of laser efficiency caused by the quenching and scattering caused by the uneven distribution of the ions. The method of the invention makes the rare earth ions and _SiO2 form a uniform and ordered structure by adopting the nanostructure assembly technology during condensation, so as to realize the uniform distribution of the rare earth ions under the condition of high doping concentration. It is beneficial to the production of high-concentration doped optical fibers.

Description

A method of making rare earth-doped optical fiber using nanometer self-assembly technology

technical field

The invention belongs to the field of optical fiber technology, and in particular relates to a method for making rare earth-doped optical fiber using nanometer self-assembly technology.

Background technique

At present, in the production of doped optical fibers, the wet doping process of using MCVD technology to make a loose layer and then soaking in a rare earth salt solution is widely used, and is currently the most important technical means for making doped optical fibers.

The process of making doped optical fiber by MCVD method is as follows: First, deposit the barrier layer (cladding layer) at high temperature as in the ordinary optical fiber manufacturing process, and then lower the temperature of the heating device (controlled at 1200 ° C ~ 1400 ° C) when depositing the core layer, At this temperature, the particles attached to the inner surface of the tube wall do not sinter to form a glass layer when heated, but exist in the form of a porous layer (soot). The method of immersing the rare earth salt solution makes the rare earth ions enter the loose layer. Then it is dried, dehydrated and other processes to remove moisture. The loose layer soaked in the rare earth salt solution is sintered and vitrified at high temperature. Finally, the rod is shrunk and drawn to produce a rare earth-doped optical fiber, which is used to make amplifiers and lasers.

The conditions of the loose layer deposited during the production of doped optical fiber preforms, such as particle size, uniformity, thickness, density, adhesion strength, etc., will affect the distribution and content of dopants in the preform. The properties of heterofibers play a crucial role.

In the case of conventional MCVD deposition, the reaction product particles form a longer tailing track under the action of the airflow, and adhere to the inner wall of the quartz tube in a longer area, and some reaction product particles are not attached to the tube wall but are lost with the airflow . When the flow rate of the reactant is increased in order to improve the deposition efficiency, the tailing track will be lengthened by the increase of the gas flow velocity, and the attachment area will also be lengthened accordingly. Excessive tailing causes some reaction product particles to go through a long process before deposition. In this process, due to the interaction between the gas flow and the reaction product particles, the uniformity of the particle layer finally attached to the tube wall will become poor, and The difference between particles undergoing different trajectories also increases significantly. This is especially evident in the low-temperature deposition of loose layers for doped optical fibers.

It can be seen that the traditional process is first to make a porous loose layer of _SiO2 , and then bring the rare earth components into the loose layer by soaking the rare earth salt solution. The rare earth doping components are concentrated in the pores of the loose layer, and its uniformity depends on the porous layer. The morphology of the loose layer is very sensitive to various parameters such as temperature and composition and is difficult to control; in addition, due to the high melting point of rare earth oxides during the melting process, it is easy to cause clusters of rare earth ions and the formation of microcrystals. In order to completely change this problem, we must start from the micro-nano structure of rare earth ion-doped quartz materials. The rapid development of nanotechnology in the field of materials makes it possible to effectively control the micro-structure of materials. Assembling nanomaterials into ordered structures of various scales will produce more excellent overall synergistic properties, so we propose to use nanostructure assembly technology in the manufacture of optical fiber preforms to make rare earth ions and _SiO2 form a uniform and ordered structure during condensation, In this way, the uniform distribution of rare earth ions under the condition of high doping concentration is realized.

Contents of the invention

The purpose of the present invention is to provide a method for making rare earth doped optical fiber using nanometer self-assembly technology, and improve the distribution uniformity of rare earth ions in optical fiber preform rod and optical fiber by using nanometer assembly technology. In order to achieve the above purpose, the present invention applies the silica nano-assembly technology in the field of materials to the fabrication of doped optical fiber preforms to form a uniform and ordered structure through nano-material assembly to achieve uniform distribution of rare earth ions in the silica optical fiber.

A method for making rare-earth-doped optical fibers using nano-self-assembly technology, which uses nano-assembly technology to distribute rare-earth ions evenly in the optical fiber, reducing the reduction in laser efficiency caused by quenching and scattering caused by uneven ion distribution , the specific schemes include the following two types: a and b:

a. Use nano self-assembly technology to build a uniform porous layer, and then use the rare earth solution doping method to uniformly dope rare earth ions into the porous layer. The specific steps are as follows:

(1) Place the quartz substrate tube for making the preform on the lathe for polishing and barrier layer deposition pretreatment;

(2) Using nano-assembly technology to build a uniform porous silica film layer on the inner wall of the quartz-based tube;

(3) After constructing the porous microstructure, the rare earth ion solution can be added into the quartz tube by online doping or offline doping.

(4) Shrunk and sintered to form a prefabricated rod of rare earth doped optical fiber.

b. Directly mix the solution containing rare earth ions with the self-assembly mother solution to directly construct a silicon dioxide film layer containing rare earth ions, the specific steps are as follows:

(1) Place the quartz substrate tube for making the preform on the lathe for polishing and barrier layer deposition pretreatment;

(2) Use nano-assembly technology to build a uniform porous silica film layer on the inner wall of the quartz-based tube, and at the same time mix the rare earth salt solution to evenly distribute the rare earth ions in the porous structure;

(3) Shrunk and sintered to form a prefabricated rod of rare earth doped optical fiber.

The on-line doping is to inject the rare earth salt solution directly from the end of the quartz tube under pressure without removing the quartz tube from the lathe.

The off-line doping is to remove the quartz tube and directly soak it in the rare earth salt solution.

The nano-assembly technology is a template technology.

In the step (1), the technology combined with MCVD is used to deposit a loose layer on the inner wall of the quartz tube when the preform is made, so as to increase the contact area and facilitate the combination with the thin film constructed by nano-assembly.

In the step (1), the technology combined with MCVD is used to perform nanometer assembly on the inner wall of the quartz tube during the fabrication of the preform rod, so as to prevent external pollution and ensure the purity of the optical fiber preform rod.

The rare earth element is Er.

The beneficial effects of the present invention are:

(1) Good doping uniformity. The uniform characteristics of the porous layer constructed by the nano-assembly method or the doped layer directly constructed are better than the void distribution characteristics of the loose layer fabricated by the traditional MCVD method.

(2) Not only rare earth ions, but also all special optical fibers that can be prepared by immersion method.

The method of the invention makes the rare earth ions and _SiO2 form a uniform and ordered structure by adopting the nanostructure assembly technology during condensation, so as to realize the uniform distribution of the rare earth ions under the condition of high doping concentration. It is beneficial to the production of high-concentration doped optical fibers.

Description of drawings

Fig. 1 is the structural representation of quartz tube of the present invention;

Fig. 2 is a schematic diagram of the structure of the deposition barrier layer on the inner wall of the quartz tube of the present invention;

Fig. 3 is the schematic diagram of the structure of the silicon dioxide thin film porous layer or doped layer made on the inner wall by the nano-assembly method of the present invention;

Fig. 4 is the schematic diagram of the structure of the preform made of the dehydration shrinkage rod of the present invention;

Labels in the figure:

detailed description

Example 1

A fiber-grade high-purity quartz tube with a size of 18mm×1.5mm (outer diameter×wall thickness) was selected as the deposition tube, and the barrier layer was deposited by the MCVD method. Shrink the two ends of the pre-high-purity quartz tube after depositing the barrier layer. Then add 20～100ml concentration of Er ³⁺ ion mother solution of 0.1～3.0mol/l from tailpipe end with feeding device on-line then, described Er ³⁺ ion mother solution is that Er ³⁺ ion solution is added ion surfactant and The template aqueous solution prepared by mixing hydrochloric acid is prepared by adding silicate, specifically adding surfactant to water, then adding Er ³⁺ ion (Er ₂ Cl ₃ ) solution, and using hydrochloric acid to control the pH value of the solution to 1-4 , and stir evenly to obtain a template aqueous solution; wherein the concentration of the surfactant is 0.5-3 mmol/L, adding a non-polar organic solvent or a polar organic solvent to the obtained template aqueous solution to make an oil-water mixture, wherein the non-polar organic The concentration of the solvent is 0.3-10mmol/L, the concentration of the polar organic solvent is 0.1-2mmol/L; the prepared oil-water mixture is added to the silicate, and the concentration of the silicate in the obtained mixture is 2.0-10mmol/L . After adding the Er ³⁺ ion mother solution, withdraw the feeding device, start to rotate the preform for 20 minutes to 200 minutes, unload the preform from the MCVD lathe, pour out the residual mother solution from the end of the tail pipe, and put it on the MCVD lathe again. The lathe rotates at a rotation rate of 10 rpm to 100 rpm for 30 minutes to 300 minutes to complete the self-assembly process (making the silica assembled into a uniform porous structure, and the Er ³⁺ ion salt solution is evenly distributed in it), and the completion doping. Then, in the case of passing high-purity oxygen and helium into the quartz tube (the volume ratio of the two is (1-10):1), heat at 100-200°C for 30-300 minutes to remove water vapor and surface Active agent residue, then pass high-purity chlorine gas and helium gas (the volume ratio of the two is (1:10) to (10:1)) at a temperature of 700-1000 ° C, further dehydration treatment for 20-200 minutes, and finally The silicon dioxide microstructure thin layer assembled by passing through high-purity oxygen is subjected to vitrification treatment at a temperature of 1500-1900°C for 10-60 minutes. If you need to further increase the thickness, you can repeat the above steps to deposit multiple times on the basis of this layer until the required thickness is reached.

Claims (7)

1. A method of using nanometer self-assembly technology to make rare-earth-doped optical fibers, characterized in that: the technology combined with MCVD is used to deposit a loose layer on the inner wall of the quartz tube during preform production, so as to increase the contact area and facilitate nanometer assembly The constructed film is combined, and then using nano-assembly technology, combined with the rotation of the quartz tube on the lathe, a uniform porous silica film layer is constructed on the loose layer, and the rare earth ions are evenly doped into the porous layer, so that the rare earth ions in the optical fiber The medium can be evenly distributed, and the reduction of laser efficiency caused by quenching and scattering caused by uneven distribution of ions is reduced. 2. The method according to claim 1, characterized in that, utilize nano self-assembly technology to construct a uniform porous layer, and then utilize rare earth solution doping method to uniformly dope rare earth ions into the porous layer, and the specific steps are as follows: (1) Place the quartz substrate tube for making the preform on a lathe for polishing and barrier layer deposition pretreatment; (2) Construct a uniform porous silicon dioxide film layer on the inner wall of the quartz-based tube using nano-assembly technology; (3) After constructing the porous microstructure, the rare earth ion solution can be added to the quartz tube by online doping or offline doping; (4) Shrunk and sintered to form a prefabricated rod of rare earth doped optical fiber. 3. method according to claim 1, is characterized in that, directly the solution that contains rare earth ion is mixed with self-assembly mother solution and directly builds the silicon dioxide film layer that contains rare earth ion, and concrete steps are as follows: (1) Place the quartz substrate tube for making the preform on a lathe for polishing and barrier layer deposition pretreatment; (2) Using nano-assembly technology to construct a uniform porous silicon dioxide film layer on the inner wall of the quartz-based tube, at the same time mixing a rare earth salt solution to evenly distribute the rare earth ions in the porous structure; (3) Shrunk and sintered to form a prefabricated rod of rare earth doped optical fiber. 4. The method according to claim 2, characterized in that: the online doping is directly injecting the rare earth salt solution from the tail end with a thin tube under pressure without removing the quartz tube from the lathe. 5. The method according to claim 2, characterized in that: the off-line doping is to remove the quartz tube and directly soak it in the rare earth salt solution. 6. The method according to claim 2 or 3, characterized in that the nano-assembly technology is template technology. 7. The method according to claim 2 or 3, characterized in that: the rare earth element is Er.