WO2020233279A1

WO2020233279A1 - Method for processing single crystal optical fiber with uniform diameter

Info

Publication number: WO2020233279A1
Application number: PCT/CN2020/084443
Authority: WO
Inventors: 李东振; 徐军; 王东海; 罗平; 王庆国; 吴锋; 唐慧丽; 徐晓东
Original assignee: 南京同溧晶体材料研究院有限公司
Priority date: 2019-05-21
Filing date: 2020-04-13
Publication date: 2020-11-26
Also published as: CN110257919A

Abstract

Provided is a method for processing a single crystal optical fiber with a uniform diameter. The single crystal optical fiber with an uniform diameter is obtained by obtaining a crystal having a length of 30-300 mm by means of a Czochralski method or another crystal growth method, successively subjecting same to processing method treatments of orientating, cutting and rounding so as to obtain a crystal bar, immersing the crystal bar in concentrated sulfuric acid and concentrated phosphoric acid at a molar ratio of (1.5-3.5) : 1, with the concentration of the concentrated sulfuric acid being 90-99.8%, and the concentration of the concentrated phosphoric acid being 60-90%, then placing same together in a muffle furnace and heating same until boiling, and setting suitable process conditions for the time and temperature; and the diameter size thereof is uniform and precise. The method has the characteristics of simple operation and easy processing, and is suitable for industrialized production.

Description

Method for processing single crystal optical fiber with uniform diameter

Technical field

The invention belongs to the field of crystal processing, and particularly relates to a method for processing a single crystal optical fiber with uniform diameter.

Background technique

Crystal fiber has been extensively studied in recent years due to its excellent performance. Generally, fiber refers to a slender round rod with a diameter on the order of micrometers to millimeters. Materials that meet this condition can be called fibers and are used to transmit light. The fiber of the signal is called an optical fiber.

Fibers of different crystal materials have been widely used in various application fields, such as sapphire fiber. Because the hardness of sapphire crystal (Mohs 9) is second only to diamond, it has high hardness and strength, wear resistance, and high temperature resistance. The characteristics of sapphire fiber and a series of characteristics such as stable chemical properties, acid and alkali corrosion resistance, so sapphire fiber is used as a metal-based reinforcement material in the aviation industry; sapphire crystal has good transmission performance in the visible light to 5.6um spectral range, and is used in military Used for electro-optical aiming; used in medicine to transmit the 2.94μm laser of Er:YAG laser; due to the high melting point and optical properties of sapphire, it can be used for high temperature measurement in industry.

Recently, rare earth-doped oxide crystal fibers used as high-power fiber lasers have become a new research focus. High-purity silica fiber has been used for 40 years. Because the thermal conductivity of silica glass is very small, only 1.4-1.6Wm-1K-1, the small thermal conductivity has a huge adverse effect on heat dissipation, so the fiber laser runs at high power. There are still higher requirements for refrigeration, which limits the continued improvement of its power. For single crystal laser gain media, the commonly used laser crystal yttrium aluminum garnet (YAG) crystal has a thermal conductivity of ~14W/mK, and the thermal conductivity of yttrium aluminate (YAP) crystal also exceeds ~11W/mK, which is higher than that of quartz glass. Therefore, single crystal can be considered as the matrix of the active fiber, and its high thermal conductivity can be used to improve the heat dissipation performance of the fiber itself, reduce the cooling requirements of the system, simplify the complexity of the system, and improve the output of the laser power and beam quality Performance.

Oxide single crystal fibers are widely used in linear and nonlinear optical devices. Can make transmission elements, activation elements and nonlinear optical elements, etc. The manufacture of these components requires single crystal fibers to be uniform in size and contain very few defects. For a single crystal fiber with a diameter of 25 μm and a length of 5 cm, a 1% diameter fluctuation will cause a 25% optical transmission loss. For the production of single crystal fiber for nonlinear components, the diameter fluctuation requirement is less than 0.1 to 1%. As we all know, the optical loss of a single crystal is mainly caused by diameter fluctuations and various crystal defects. For bulk single crystals, rods with uniform size and few defects can be selected by mechanical processing, while single crystal fibers have a small diameter (usually <500μm), and it is difficult to process single crystal fibers with a diameter of less than 2mm by mechanical processing. Especially when the optical fiber length>100mm, the processing yield is less than 60%. Crystal fibers with a diameter of less than 2 mm are usually obtained by crystal growth. The existing common methods for growing oxide crystal fibers include micro pull-down method, laser heating pedestal method, and guided mode method, all of which face the problem of large fluctuations in fiber diameter. Therefore, how to obtain crystal fibers with uniform diameter has become an important research topic.

Summary of the invention

The purpose of the present invention is to solve the problem that it is difficult to obtain a single crystal fiber with uniform diameter in the prior art. To achieve the above object, the present invention provides a method for processing a single crystal fiber with uniform diameter, which is simple to operate, easy to process, and obtainable. The specific method steps of crystal fibers with uniform diameters of different oxide single crystals are:

(1) Obtain crystals with a length of 30-300mm through the crystal growth method of the pulling method; (2) Obtain crystal rods with a uniform diameter of about 1.5-4.5mm through the processing methods of orientation, cutting, and rounding successively; (3) Place the spheronized crystal rod in a quartz or glassware with a lid of matching length; (4) Pour a certain concentration of concentrated sulfuric acid and concentrated phosphoric acid into the above-mentioned container with crystal rod, and set the height of the acid solution to exceed The height of the top of the crystal rod is 1cm-10cm; (5) Put the vessel containing the crystal rod and acid solution into the muffle furnace, and heat it to 300-380°C at a heating rate of 100-300°C/h at a constant temperature; During the constant temperature period, take out the ingot to measure the diameter, and stop the measurement when the required fiber diameter is reached. The measured diameter is drawn as the diameter change curve with time as the basis for later production process control.

As an improvement, in step (4), the concentration of the concentrated sulfuric acid solution is 90%-99.8%, the concentration of the concentrated phosphoric acid solution is 60%-90%, and the molar ratio of concentrated sulfuric acid and concentrated phosphoric acid is (1.5-3.5): 1.

As an improvement, the optical fiber is a sapphire or garnet optical fiber.

Beneficial effects: The method for processing a single crystal optical fiber with uniform diameter provided by the present invention involves immersing a crystal rod in concentrated sulfuric acid and concentrated phosphoric acid with a molar ratio of (1.5-3.5):1, wherein the concentration of the concentrated sulfuric acid solution is 90%-99.8% , The concentration of the concentrated phosphoric acid solution is 60% to 90%, placed together in the muffle furnace, set the appropriate time and temperature under the process conditions, obtain a single crystal fiber with uniform diameter, the diameter is more uniform and accurate, Simple and easy to process.

The above description is only an overview of the technical solution of the present invention. In order to understand the technical means of the present invention more clearly and implement it in accordance with the content of the description, the preferred embodiments of the present invention are described in detail below with the accompanying drawings.

Description of the drawings

Figure 1 is a scanning electron micrograph of a fiber with a diameter of 800 μm obtained in the present invention.

Detailed ways

The specific embodiments of the present invention will be described in further detail below in conjunction with the drawings and embodiments. The following examples are used to illustrate the present invention, but not to limit the scope of the present invention.

A method for processing a single crystal fiber with uniform diameter. First, crystals with a length of 30-300mm are obtained by pulling or other crystal growth methods; and a uniform diameter of about 1.5-4.5mm is obtained by processing methods of orientation, cutting, and rounding in turn. Place the spheronized crystal rod in a quartz or glassware with a lid of matching length; pour a certain concentration of concentrated sulfuric acid and concentrated phosphoric acid into the above-mentioned container with the crystal rod in turn, and set the height of the acid The height beyond the top of the crystal rod is 1cm-10cm; put the utensils containing the crystal rod and the acid solution into the muffle furnace, and the heating rate is 100-300℃/h, heated to 300-380℃, constant temperature; During the interval of 5-15 minutes, take out the ingot to measure the diameter, and stop the measurement until the required fiber diameter is reached. The measured diameter is drawn as a diameter change curve with time. The drawing curve will get the diameter change rate for precise control of corrosion in the future. time.

Preferably, the concentration of the concentrated sulfuric acid, the concentration of the concentrated phosphoric acid solution, and the corrosion time of the concentrated sulfuric acid are determined according to the material type of the optical fiber to be processed, the diameter of the optical fiber and the diameter of the prepared optical fiber.

Example 1

Obtain crystals with a length of 30-100mm by the pulling method; obtain ingots with a uniform diameter of about 1.5-2.5mm through the processing methods of orientation, cutting and spheronization in turn; place the spheronized ingots on a cover with matching length Quartz or glassware; Pour the concentration of 90% concentrated sulfuric acid and 60-75% concentrated phosphoric acid into the above-mentioned vessel with crystal rods in turn, the molar ratio of concentrated sulfuric acid to concentrated phosphoric acid is (1.5-2):1 .

Set the height of the acid solution beyond the height of the top of the crystal rod to be 1cm-10cm; put the vessel containing the crystal rod and acid solution into the muffle furnace, and heat to 300-340℃ at a heating rate of 100-220℃/h , Constant temperature; during the constant temperature period, take out the crystal rod to measure the diameter, and stop the measurement after reaching the required fiber diameter of 800μm. The measured diameter is plotted as the diameter change curve with time. The drawing curve will get the diameter change rate. It will be used to accurately control the corrosion time in the future, where the diameter change rate is the fitting slope value of the change curve.

Example 2

Obtain crystals with a length of 120-300mm by the pulling method; sequentially obtain crystal rods with a diameter of about 2.5-4.5mm through the processing methods of orientation, cutting, and rounding; place the rounded crystal rods in a matching length with a cover Quartz or glassware; Pour the concentration of 97-99% concentrated sulfuric acid and 75-90% concentrated phosphoric acid into the above-mentioned utensils with crystal rods. The molar ratio of concentrated sulfuric acid to concentrated phosphoric acid is (2-3.5 ):1.

Set the height of the acid solution beyond the height of the top of the crystal rod to be 1cm-10cm; put the utensils containing the crystal rod and acid solution into the muffle furnace, and heat it to 350-380℃ at a heating rate of 220-300℃/h , Constant temperature; During the constant temperature period, take out the crystal rod and measure the diameter until it reaches the required fiber diameter of 820μm and then stop the measurement. The measured diameter is plotted as the diameter change curve with time. The drawing curve will get the diameter change rate. It will be used to accurately control the corrosion time in the future, where the diameter change rate is the fitting slope value of the change curve.

The above-mentioned embodiments only express several embodiments of the present invention, and the descriptions are more specific and detailed, but they should not be understood as limiting the scope of the invention patent. It should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can be made, and these all fall within the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention should be subject to the appended claims.

Claims

A method for processing a single crystal optical fiber with uniform diameter is characterized in that the specific method steps are:

(1) Obtain crystals with a length of 30-300mm through the pulling method; (2) Obtain crystal rods with a diameter of about 1.5-4.5mm through the processing methods of orientation, cutting, and rounding; (3) Rounded The crystal rods are placed flat in a quartz or glassware with a lid of matching length; (4) Pour a certain concentration of concentrated sulfuric acid and concentrated phosphoric acid into the above-mentioned utensils with crystal rods in sequence, and set the acid liquid level above the upper end The height of the crystal rod is 1cm-10cm; (5) Put the utensil containing the crystal rod and the mixed acid solution into the muffle furnace, and heat it to 300-380℃ at a heating rate of 100-300℃/h. During the constant temperature period, take out the ingot to measure the diameter, and stop the measurement until the required fiber diameter is reached. The measured diameter is drawn as the diameter change curve with time as the basis for the later production process control.
The method for processing a uniform diameter single crystal optical fiber according to claim 1, wherein the concentration of the concentrated sulfuric acid solution in step (4) is 90%-99.8%, and the concentration of the concentrated phosphoric acid solution is 60%-99.8%. %, the molar ratio of concentrated sulfuric acid and concentrated phosphoric acid is (1.5-3.5):1.
The method for processing a single crystal optical fiber with uniform diameter according to claim 1, wherein the optical fiber is a sapphire or garnet fiber or other oxide crystal fiber.