Study On Hydroxyl Control Technology Of G.652D Optical Fiber Preform Based On "VAD+OVD" Two-step Method

In 1966,Gao Kun first proposed the theory of using glass fiber as an optical waveguide for information transmission.For more than 40 years,the optical fiber industry has developed rapidly.With the increasing demand for high-speed,long-distance and large-capacity transmission of optical fiber transmission systems,problems such as fiber attenuation,dispersion,and nonlinear effects are becoming more and more prominent,which seriously restricts the quality of fiber-optic systems.G.652D fiber is an important category in single-mode fiber and has excellent comprehensive performance.However,the problem of hydroxyl control(subtraction)of G652D fiber preform has not been well solved.In order to systematically improve the comprehensive performance of G.652D fiber,this thesis mainly carried out the research on the hydroxyl control process of G.652D optical fiber preform based on the "VAD+OVD" two-step method,realizing the attenuation average of the fiber drawing at 1383nm at 0.275±0.005dB/km,reaching the industry leading level.The paper mainly carried out the following aspects:1)By studying the relationship between the flow rate of raw materials and d/a,it is found that decreasing the flow rate of Core SiC14 and increasing Clad 2 SiC14 are beneficial to increasing d/a,while increasing the deposition rate of mandrel can reduce the hydroxyl content.2)Reducing the flow rate of Core/Cladl/Clad2 H2 in core rod deposition is beneficial to reducing the formation of Si-O bond and hydrogen peroxide,thus reducing the formation of Si-OH by the combination of Si-O bond and hydrogen peroxide.3)It was found that the flow rate of Cl2,dehydroxylation time and dehydroxylation temperature of sintered mandrel all affected the dehydroxylation effect.Increasing sintering dehydroxylation time of mandrel has obvious effect on reducing hydroxyl content;890? is the appropriate dehydroxylation temperature;and 800cc/min is the appropriate flow control of C12.4)As the flow rate of H2 decreases,the SiH or OH groups formed by the combination of hydrogen with E' defect and non-bridge oxygen defect decrease,which reduces the hydroxyl content to a certain extent.5)The effect of reducing the flow rate of H2 deposited by secondary deposition is similar to that of Core/Cladl/Clad2 H2 deposited by mandrel.It can also reduce the formation of Si-O bond and hydrogen peroxide,thus reducing the formation of Si-OH by the combination of Si-O bond and hydrogen peroxide.6)Reducing the descending rate of base material for outsourcing sintering has no obvious effect on reducing hydroxyl content.In terms of temperature,1300 C is a suitable dehydroxylation temperature.It is advisable to control Cl2 flow at 1000cc/min.7)After the combination of the six processes,an optimal hydroxyl control process can be obtained.The drawing water peak of G.652D optical fiber preform can reach 0.273dB/km.