A method for growing crystal cladding in a metal tube

Abstract

The invention relates to a method for growing crystal cladding in a metal tube. The method includes: inserting a crystal optical fiber into a metal sleeve, wherein the core diameter of the sleeve is 0.1-0.8mm larger than the diameter of the optical fiber, and the lower end of the sleeve is provided with a metal wire with the diameter being identical with the diameter of the crystal optical fiber;mounting to a crystal growth pulling furnace seed rod, heating raw materials in a pulling furnace crucible until the raw materials melt, and lowering the seed rod to allow the metal wire at the lowerend of the metal sleeve to be partially soaked into the melt so as to allow the melt to climb along gaps among the metal sleeve, the crystal optical fiber and the metal wire under a capillary effect,wherein the length of the part, exposed out of the liquid surface, of the upper end of the metal wire is 2-3mm; continuing rising the temperature of the melt in the crucible to allow the melt to fillthe gap between the metal sleeve and the crystal optical fiber; pulling the metal sleeve out of the melt in the crucible at the pulling rate of 5-10mm / h, and cooling to room temperature to obtain thecrystal optical fiber with the crystal cladding. Compared with the prior art, the method has the advantages that the crystal core can be seamlessly connected with the crystal cladding, uniform refractive index distribution can be obtained, and a high-power crystal optical fiber laser device can be obtained.

Description

Technical field [0001] The invention belongs to the technical field of crystal material preparation, and relates to a manufacturing process of a high-power fiber laser fiber and a cladding. Background technique [0002] Quartz fiber has made outstanding contributions to optical communications, and some people want to use it as a high-power laser to solve the problem of thermal effects faced by high-power lasers. Thermal effects can cause thermal depolarization and thermally induced diffraction loss, which seriously affect the laser The main performance indicators such as the output power, conversion efficiency and beam quality of the high-power laser, and even damage to the gain medium in severe cases, are the main limiting factors for the performance of high-power lasers. In order to alleviate the impact of thermal effects, technicians in related fields use gain media in the form of slats, DISKs and optical fibers to increase the surface area to volume ratio of the gain media an...

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Problems solved by technology

[0003] However, almost all optical fibers need cladding, not only to confine the beam inside the fiber, but also to isolate the fiber from the surrounding environment to maintain the integrity of the fiber. The cladding can also be used to increase the strength of the fiber. For Silica optical fiber, the cladding of the optical fiber is made by putting the quartz tube and the quartz core together to make a prefabricated rod, which is co-drawn in the fiber drawing tower, because the quartz is heated to soften and has a state between solid and liquid. The softened state exists, the dopant that has been doped into the core will not diffuse, and the refractive index distribution in the original preform will be maintained. For the crystal fiber, since the crystal is in a liquid state after melting, it can diffuse freely, so the dopant in the core rod It is possible for the ions to diffuse into the tube rod, and the tube rod as the fiber cladding does not allow the presence of doping ions, so it is not advisable to make the crystal cladding by the method of making the quartz cladding

Units at home and abroad are trying sol-gel to make crystal optical fiber cladding, but no substantial progress has been made, because the efficiency of sol-gel is too low, and the cladding with a thickness of 5 μm can only be obtained after 10 sol-gel operations, which is far from the final The usable thickness of 200-300μm is far away, and the cladding made by sol-gel is easy to crack

At present, there is no mature process report on crystal fiber with crystal cladding at home and abroad. It is reported that the crystal core and quartz cladding are used. Good beam quality, but it does not have much effect on the amplification of laser power. The US ArmyResearch Laboratory and ONYX Optics turned to study planar guided waves---that is, the cross-section of the core rod and cladding was made square, and the core and cladding They are tightly bonded by thermal bonding, and the all-crystal fiber is truly achieved, but the qualification rate of this thermal bonding process is not high.

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