CN106517759A - Homogenizing preparation method of rare-earth-doped quartz glass rods - Google Patents

Abstract

A method for homogenizing rare earth-doped quartz glass rods. The method uses a high-temperature micro-zone heating process, utilizes rotational shear stress, and performs secondary melting and homogenization treatment on the glass rods in an oxygen-enriched atmosphere, thereby improving the core rod glass. uniformity. The method utilizes an oxygen-enriched atmosphere to reduce the content of low-valence impurity ions, which is beneficial to reducing glass loss.

Description

Homogenization preparation method of rare earth doped quartz glass rod

technical field

The invention relates to an optical fiber prefabricated rod and laser glass, in particular to a preparation method of a large-mode field-doped rare earth-doped rare earth quartz optical fiber prefabricated rod core rod and a homogenized preparation method of quartz-based laser glass.

Background technique

In order to meet the higher laser power requirements of industrial processing applications, while reducing the laser power per unit area of rare earth-doped silica fibers, reducing nonlinear effects and laser damage, high-power laser fibers are developing in the direction of large-mode-field fibers. . Since 2004, the University of Southampton (Optics Express, 2004, Vol.12, No.25, pp.6088-6092) and the German Jena Photonic Technology Institute have joined forces with Heraeus (SPIE Conference Proceedings, Volume 6873 in 2008) , pp.687311-1-9) carried out the development of large mode field Yb-doped special optical fiber.

At present, the relatively mature preparation method of rare earth doped silica optical fiber preform is the improved chemical vapor deposition (MCVD) combined with solution immersion method. The disadvantage of this method is: due to the limitation of doping uniformity and stress control in the doping process, it is difficult to realize the preparation of a rare earth doped quartz core rod with a large core diameter. A United States patent (US 2010/0251771 A1) jointly applied by the Heraeus company of Germany and the Institute of Photon Technology of Germany Jena, which was published in 2010, proposes a method for preparing doped quartz glass. The method starts from an ammonia solution containing 50 wt% silicon oxide nanopowder, and adds an aqueous solution of AlCl ₃ and YbCl ₃ to form SiO ₂ particles uniformly doped with Al ³⁺ and Yb ³⁺ ions. Uniformly doped quartz glass is formed by granulation, drying, isostatic pressing, dehydration, sintering and vitrification. Using this method, a Yb-doped quartz glass core rod with a length of 200mm and a diameter of 15mm can be prepared, and a Yb-doped quartz large-mode-field rod optical fiber with a background loss of 50dB/km at 1200nm can be prepared by using it. But the limitation of this method is that it can only realize the preparation of Yb ³⁺ , Al ³⁺ co-doped quartz glass core rod, and cannot realize Yb ³⁺ , Al ³⁺ , P ⁵⁺ co-doping, so it is difficult to control high-power laser Photodarkening effect in case of output application. Moreover, this method starts from the solid phase of silicon oxide nanopowder, which is difficult to fundamentally solve the problem of optical uniformity of the core rod glass.

The invention patent of YOFC Optical Fiber and Cable Co., Ltd. published in March 2013, "A Rare Earth Uniformly Doped Prefabricated Rod and Its Preparation" (Publication No.: CN 102992613 A). The method adopts 10-200nm nano-silica powder as a raw material, dissolves it in water or ethanol solution with pH=7-11 and contains dopant ions, and obtains the dopant-containing silicon oxide powder after dehydration and granulation. The quartz glass core rod doped with rare earth ions is obtained by isostatic pressing and atmosphere sintering. The invention obtains a core rod glass whose refractive index fluctuation is within ±10%. However, this invention uses nano-silicon oxide raw materials instead of preparing powder from a pure solution method, so it is difficult to fundamentally solve the uniformity problem in the case of multiple doping ions.

In 2013, the inventor's research group developed a technology for preparing a large-mode-field ytterbium-doped optical fiber preform core rod by a sol-gel process, and applied for the invention patent "Preparation method of Yb-doped silica optical fiber preform core rod" ( Patent Publication No. 103373811A). This invention patent focuses on the preparation method of large-sized ytterbium-doped core rod glass. The disadvantage is that the content of divalent ytterbium ions and low-valent impurity ions in the glass is still high, resulting in a high final optical fiber loss. Level. On the other hand, the optical uniformity of rare earth-doped quartz glass is still poor, which cannot meet the application requirements of laser glass media.

Contents of the invention

Aiming at the deficiencies and defects of the above-mentioned prior art, the present invention provides a method for homogenizing rare earth-doped quartz glass rods according to the development requirements of high-power fiber lasers and solid-state lasers. The rare earth-doped quartz glass rod obtained by applying the method can be used not only to prepare a large-size, high-uniformity large-mode-field double-clad rare-earth-doped silica optical fiber, but also to prepare rare-earth-doped silica glass with higher optical uniformity.

Technical solution of the present invention is:

A method for homogenizing a rare earth-doped quartz glass rod, comprising the following steps:

①Process the rare earth-doped quartz glass prepared based on the powder sintering process into a glass rod with a diameter of 6-10mm and a length of 50-200mm, place it on a glass lamp lathe, and use a hydrogen-oxygen flame to heat the micro-area, and adjust the flame to heat the high-temperature area The length is less than 1cm. According to the chemical reaction ratio, hydrogen and oxygen react to form water according to the relationship of 2 to 1. In order to obtain an oxygen-rich atmosphere, it is necessary to increase the flow rate of oxygen to increase the flow ratio of oxygen to hydrogen from the conventional 0.5 to 1. The temperature ranges from 2000°C to 2100°C. Use the lathe to rotate the high-temperature heated glass area to perform a second high-temperature homogenization treatment. The rotation speed of the lathe should be such that the rare earth-doped quartz glass will not soften and fall due to gravity. Usually, the rotation speed is 60 -70 revolutions per minute, the hydrogen-oxygen flame slowly reciprocates from one end to the other for heating at a certain speed, usually the flame moving speed is 30-40mm/min;

②The number of reciprocating heating and homogenization of the above-mentioned rare earth-doped quartz glass rod is 10-15 times;

③ Adjust the temperature of the hydrogen-oxygen flame to about 1500°C-1600°C, move and heat the above-mentioned homogenized rare earth-doped quartz glass rod from one end to the other end for annealing treatment, and the flame moving speed is 80-100mm/min;

④ After the glass annealing is completed, the rare earth doped quartz glass rod is removed to obtain a rare earth doped quartz glass rod with high optical uniformity.

Optically process the rare earth-doped quartz glass rod after the above secondary heating and homogenization to obtain a rare earth-doped quartz glass rod with a diameter required for practical application. The glass rod can be used as an optical fiber preform core rod or as a rod Laser glass medium.

Beneficial effects of the present invention:

1. It can effectively improve the optical uniformity of rare earth doped quartz glass;

2. It can effectively reduce the content of low-valent rare earth ions and impurity ions, which is beneficial to the improvement of luminescence performance and the reduction of optical fiber loss;

Description of drawings

Fig. 1 is a comparison of the microfluorescent photos before and after secondary melting and homogenization of the ytterbium-doped quartz glass rod in Example 1, wherein a is the micro-fluorescent photo of the ytterbium-doped quartz glass rod micro-region heating in Example 1 before the second melting and homogenization , b is the micro-fluorescent photo of Example 1 after the ytterbium-doped quartz glass rod micro-region is heated for the second time and melted and homogenized.

Figure 2 is a photomicrograph of the rare earth-doped silica fiber prepared before and after secondary melting and homogenization of the ytterbium-doped mandrel in the application example. The photomicrograph of the prepared rare earth-doped silica fiber, b is the photomicrograph of the rare earth-doped silica fiber prepared after secondary melting and homogenization of the ytterbium-doped mandrel micro-region heating in the application example.

detailed description

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

In the present invention, the prepared rare-earth-doped quartz glass rod is placed on a glass lathe, and an oxygen-hydrogen flame is used to heat a local micro-region of the mandrel glass, and the mandrel is in a rotating state during heating. Excessive oxygen is obtained during heating to obtain an oxygen-rich atmosphere. In the softened state of the doped quartz glass, the glass is oxidized and high-temperature homogenized, thereby effectively reducing the content of low-valent ions inside the glass and greatly improving the uniformity of the glass.

Example 1:

In this embodiment, the ytterbium-doped quartz glass rod fired by the powder sintering process is used for high-temperature micro-zone heating to homogenize and prepare a high-quality rare earth-doped quartz glass rod. The method includes the following steps:

①Process the rare earth-doped quartz glass prepared based on the powder sintering process into a glass rod with a diameter of 10mm and a length of 50mm, place it on a glass lamp lathe, and use a hydrogen-oxygen flame for micro-area heating. Adjust the flame so that the length of the high-temperature heating zone is less than 1cm. According to the chemical reaction ratio, hydrogen and oxygen react to form water according to the ratio of 2 to 1. In order to obtain an oxygen-rich atmosphere, it is necessary to increase the oxygen flow rate, so that the flow ratio of oxygen and hydrogen gas is increased from the conventional 0.5 to 1, and the heating temperature is 2000 °C , using lathe rotation to carry out secondary high-temperature homogenization treatment on the high-temperature heated glass area; the lathe rotation speed is 60 rpm, and the hydrogen-oxygen flame slowly reciprocates from one end to the other end at a speed of 30 mm/min for heating.

② The above-mentioned rare earth-doped quartz glass rod reciprocates, heats and homogenizes for 15 times, stops heating, and completes the high-temperature homogenization process.

③ Adjust the temperature of the hydrogen-oxygen flame to about 1600°C, move and heat the homogenized rare earth-doped quartz glass rod from one end to the other end for low-temperature annealing treatment, and the flame moving speed is 80mm/min.

④ After the glass annealing is completed, the rare earth-doped quartz glass rod is removed to prepare a rare earth-doped quartz glass rod with high optical uniformity.

Microfluorescence analysis was performed on the core rod glass before and after secondary heating and homogenization, and the results are shown in Figure 1. It can be seen that the luminescence of the glass after the high-temperature micro-area heating treatment becomes more uniform.

Example 2:

In this embodiment, the ytterbium-doped quartz glass rod fired by the powder sintering process is used for high-temperature micro-zone heating to homogenize and prepare a high-quality rare earth-doped quartz glass rod. The method includes the following steps:

①Process the rare earth-doped quartz glass prepared based on the powder sintering process into a glass rod with a diameter of 6mm and a length of 200mm, place it on a glass lamp lathe, and use a hydrogen-oxygen flame for micro-area heating. Adjust the flame so that the length of the heating high-temperature zone is less than 1cm. According to the chemical reaction ratio, hydrogen and oxygen react to form water according to the ratio of 2 to 1. In order to obtain an oxygen-rich atmosphere, it is necessary to increase the flow rate of oxygen, so that the flow ratio of oxygen and hydrogen is increased from the conventional 0.5 to 1, and the heating temperature is 2100°C , using lathe rotation to perform secondary high-temperature homogenization treatment on the high-temperature heated glass area. The turning speed of the lathe is 80 rpm, and the oxyhydrogen flame slowly reciprocates from one end to the other end for heating at a speed of 40mm/min.

⑤ The above-mentioned rare earth-doped quartz glass rod reciprocates, heats and homogenizes 10 times, stops heating, and completes the high-temperature homogenization process.

⑥ Adjust the temperature of the hydrogen-oxygen flame to about 1500°C, move and heat the homogenized rare earth-doped quartz glass rod from one end to the other end for low-temperature annealing treatment, and the flame moving speed is 100mm/min.

⑦ After the glass annealing is completed, the rare earth-doped quartz glass rod is removed to prepare a rare earth-doped quartz glass rod with high optical uniformity.

Example 3:

In this embodiment, high-quality Nd-doped quartz glass rods are prepared by homogenizing Nd-doped quartz glass rods fired by powder sintering technology for high-temperature micro-zone heating. The method includes the following steps:

① Process the neodymium-doped quartz glass prepared based on the powder sintering process into a glass rod with a diameter of 6mm and a length of 100mm, place it on a glass lamp lathe, and use a hydrogen-oxygen flame for micro-area heating. Adjust the flame so that the length of the high-temperature heating zone is less than 1cm. According to the chemical reaction ratio, hydrogen and oxygen react to form water according to the ratio of 2 to 1. In order to obtain an oxygen-rich atmosphere, it is necessary to increase the flow rate of oxygen, so that the flow ratio of oxygen and hydrogen is increased from the conventional 0.5 to 1, and the heating temperature is 2000°C , using lathe rotation to perform secondary high-temperature homogenization treatment on the high-temperature heated glass area. The turning speed of the lathe is 60 rpm, and the hydrogen-oxygen flame slowly reciprocates from one end to the other end at a speed of 30 mm/min for heating;

②The above-mentioned rare earth-doped quartz glass rod reciprocates, heats and homogenizes 10 times, stops heating, and completes the high-temperature homogenization process;

③ Adjust the temperature of the hydrogen-oxygen flame to about 1600°C, move and heat the homogenized rare earth-doped quartz glass rod from one end to the other end for low-temperature annealing treatment, and the flame moving speed is 100mm/min;

④ After the glass annealing is completed, the neodymium-doped quartz glass rod is removed to obtain a neodymium-doped quartz glass rod with high optical uniformity.

Application example

Using the ytterbium-doped silica glass rod homogenized in Example 1 as the core rod, the optical fiber was drawn by the sleeve method, and the microscopic appearance of the glass drawn optical fiber before and after homogenization was compared and tested, as shown in FIG. 2 . It can be seen that the internal optical uniformity of the optical fiber prepared by the core rod glass after high-temperature micro-zone heating treatment is significantly improved compared with the untreated core rod.

Claims (1)

1. A method for homogenizing a rare earth-doped quartz glass rod, characterized in that the method comprises the following steps: ①Process the rare earth-doped quartz glass prepared based on the powder sintering process into a glass rod with a diameter of 6-10mm and a length of 50-200mm, place it on a glass lamp lathe, and use a hydrogen-oxygen flame for micro-area heating. Adjust the flame to make the heating temperature high The length of the zone is less than 1cm. According to the chemical reaction ratio, hydrogen and oxygen react to form water according to the relationship of 2 to 1. In order to obtain an oxygen-rich atmosphere, it is necessary to increase the flow rate of oxygen to increase the flow ratio of oxygen to hydrogen from the conventional 0.5 to 1. The heating temperature ranges from 2000°C to 2100°C, and the high-temperature heated glass area is subjected to secondary high-temperature homogenization treatment by rotating the lathe. The rotation speed of the lathe is such that the rare earth doped quartz glass will not soften and fall due to gravity. 60-70 revolutions per minute, the hydrogen-oxygen flame slowly reciprocates from one end to the other for heating at a certain speed, usually the flame moving speed is 30-40mm/min; ②The number of reciprocating heating and homogenization of the above-mentioned rare earth-doped quartz glass rod is 10-15 times; ③ Adjust the temperature of the hydrogen-oxygen flame to about 1500°C-1600°C, move and heat the above-mentioned homogenized rare earth-doped quartz glass rod from one end to the other end for annealing treatment, and the flame moving speed is 80-100mm/min; ④ After the glass annealing is completed, the rare earth doped quartz glass rod is removed to obtain a rare earth doped quartz glass rod with high optical uniformity.