Low-loss optical fiber preform outer cladding, preparation equipment and preparation method thereof, and optical fiber

Abstract

The invention relates to a low-loss optical fiber preform outer cladding, preparation equipment and a preparation method thereof, and an optical fiber. One of four processes of VAD, OVD, MCVD and PCVDis selected to prepare a core rod; plasma is used as a heat source on the surface of the core rod; silicon tetrachloride is subjected to high-temperature oxidation, a high-density silicon dioxide outer cladding layer is generated and deposited on the surface of the core rod; finally, the set target rod diameter is reached; the outer cladding layer has good optical uniformity, high hardness and low stress birefringence, and the 1310 nm attenuation of a G.652D optical fiber preform prepared by the outer cladding method after drawing can reach 0.315 dB / km, and the 1550 nm attenuation can reach 0.175 dB / km. Compared with the prior art, high-temperature plasma is used for pretreating the surface of the core rod, the problem of interface defects is solved, silicon tetrachloride is used as a rawmaterial, high-temperature plasma is used as a heat source, the optical fiber preform outer cladding layer with high compactness, high uniformity and low defects is generated, and the preparation requirement of the low-loss optical fiber preform is met.

Description

Technical field [0001] The invention relates to the technical field of optical fiber communication, in particular to a low-loss optical fiber preform outer cladding, preparation equipment, preparation method and optical fiber. Background technique [0002] The optical fiber preform is divided into two parts: the core rod and the outer cladding. In the existing optical fiber preform manufacturing methods, the axial vapor deposition method (VAD), the external vapor deposition method (OVD), the improved chemical vapor deposition (MCVD) and plasma Bulk chemical vapor deposition (PCVD) can be used for the preparation of core rods; the production methods of the outer coating are mainly concentrated in the RIT / RIC method (tube method), Soot method (external vapor deposition) and external plasma spraying method. RIT The / RIC method is to insert the core rod into the sleeve to directly draw the optical fiber, or to melt it into a solid preform and then draw the wire; the Soot method and t...

AI Technical Summary

Problems solved by technology

In this technical solution, because quartz sand is used as raw material, its purity and quality consistency is not good, so the prepared preform outer casing will contain the original impurities of quartz sand, which will affect the loss. On the other hand, this solution needs to prepare the outer cladding first. The tube is combined with the mandrel for wire drawing, and the interface structure between the outer cladding sleeve and the mandrel surface is imperfect, which causes Rayleigh scattering to increase, thereby affecting the loss

[0005] The existing outer cladding technology of optical fiber preform is mainly based on external vapor deposition (OVD), which uses SiCl 4 As raw material, through hydrogen and oxygen combustion, high temperature hydrolysis to generate nano-scale SiO 2 The powder is deposited on the surface of the core rod, and then dehydroxylated and sintered into a transparent optical fiber preform in a chlorine atmosphere. The outer cladding density fluctuates greatly after depositing the powder first and then sintering, so the Rayleigh scattering of the optical fiber preform produced by this outer cladding technology is relatively large, making it difficult to obtain better loss

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