A high-power optical fiber end cap and its manufacturing method

Abstract

The invention provides a high-power optical fiber end cap and a manufacturing method thereof. The optical fiber end cap comprises a double-clad optical fiber, a core-free optical fiber and a quartz rod which are coaxially arranged; the quartz rod comprises a first cylindrical section, a circular table section and a second cylindrical section which are coaxially connected in sequence, the diameterof the first cylindrical section is smaller than that of the second cylindrical section; the double-clad optical fiber is connected with one end of the core-free optical fiber in a welding mode, and the other end of the core-free optical fiber is connected with one end of the first cylindrical section in a welding mode; the diameter of the cladding layer of the core-free optical fiber is larger than or equal to the diameter of the double-clad optical fiber; and the diameter of the cladding layer of the core-free optical fiber is smaller than or equal to the diameter of the first cylindrical section. The laser firstly passes through the core-free optical fiber, so that energy is expanded, and the light power density in the connecting place of the output end plane and the quartz rod is lowered; by selecting the proper length of the core-free optical fiber, the output light spot can be large enough when the laser outputs from the core-free optical fiber, so that the optical power densityon the output surface can be effectively reduced; and meanwhile, energy is not output from the side surface of the core-free optical fiber, and loss of energy is avoided.

Description

technical field [0001] The invention relates to a fiber laser and a laser transmission system, in particular to a high-power fiber end cap and a manufacturing method thereof. Background technique [0002] In recent years, high-power fiber lasers have been the focus of attention in the laser field. Because of their high optical power density, good beam quality, and ease of use, they are widely used in industrial processing, weaponry, and medical equipment. The high-power laser is equipped with a high-power energy-transmitting optical cable, which can make the laser more flexible and controllable, and realize flexible three-dimensional processing; at the same time, its transmission beam quality is excellent and the optical power density is large. Since the fiber used in high-power fiber lasers is usually a double-clad fiber with a large mode field area, the core diameter is only 10μm-30μm, and the power density of the light in the fiber core is very high. It may strengthen th...

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Problems solved by technology

[0005] High-power fiber laser end caps are usually composed of an optical fiber and a large-diameter quartz cone rod. However, the size difference between the quartz cone rod and the optical fiber is large, which makes it difficult to control the temperature during fusion. Therefore, the quality of the fusion is difficult to guarantee.

At the same time, the core area of ​​the single-mode fiber is small, and the optical power density on the output surface is high, so it is very easy to generate a strong temperature rise due to the tiny defect of the fusion joint, which in turn leads to damage to the end cap.

Using a tapered quartz rod to weld the optical fiber to the thin end of the tapered quartz rod can solve this problem to a certain extent, but because the diameter of the thin end of the quartz rod is still much larger than the diameter of the optical fiber, there are still difficulties in welding, Disadvantages such as high optical power density at the welding point

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