MCVD工艺制备光纤(制造工艺).ppt

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1、VAD（轴向汽相沉积）OVD （外部汽相沉积）MCVD（改进的化学汽相沉积）PCVD（等离子体化学汽相沉积） Main variables for each process steps are following: Gas flows: bubbler carrier gas, O2, He, Cl2, SF6 etc. Preform temperature Carriage speed Sootbox pressure Ramping of relevant parameters Typical MCVD production tube is constructed from three

2、quartz tubes,which are welded together prior to MCVD process. inlet tube: low quality quartz substrate tube: high quality synthetic silica, forms final preform exhaust tube: low quality quartz sleeving tube: synthetic silica Purpose: To clean tube outer and inner surface to improve preform quality.

3、Temperature: 1850-2200C Reactant flows: O2 + fluorine source for etchingSF6+O2Cladding deposition Purpose: deposition of protection barrier for core. Temperature: 1900-2100oC Typical reactant flows: SiCl4,POCl3, O2, HeCore deposition Purpose: deposition of refractiveindex difference Temperature: 190

4、0-2200oC Typical reactant flows: SiCl4,GeCl4, O2, HeSiCl4+O2=SiO2+2Cl2 GeCl4+O2=GeO2+2Cl24POCl3+3O2=2P2O5+6Cl2 4BCl3+3O2=2B2O3+6Cl2热泳现象热泳现象是指在温度梯度不为零的气体或悬浮体中，粒子向较冷区域运动的现象。热泳速度正比于温度梯度，而与粒径无关。 Purpose: to produce glass rod for jacketing and fiber drawing Typically 2 to 5 forward and 1 backward steps T

5、emperature: 2000-2400oC Chlorine used as a drying agent dimensional and optical parameter evaluation. important process and quality control tool Preform dimensions Preform, cladding and core diameters from different angles and longitudinal positions Refractive indices Substrate tube, cladding and co

6、re from different longitudinal positions Cutoff, MFD, Chromatic dispersion Preform non-circularity (preform, cladding, core) Preform concentricity (preform, cladding, core) Purpose: enlarge preform size to improve MCVD productivity Typical final preform size: 40 to 80 mm Temperature: 2000C Vacuum su

7、ction between rod and tube to accelerate joining process1.Lathe 2. Gas Control System 3. PC/PLC Control System 4. Gas & Water Supply 5. Extract Systems.Oxy-hydrogen burnerPyrometerFlame detectorSilicon Tetrachloride (SiCl4) SupplyGermanium Tetrachloride (GeCl4) SupplyPhosphoryl Chloride (POCl3) Supp

8、lyBoron trichloride (BCl3) SupplyLathe Hydrogen&Oxygen SupplySulphur Hexafluoride (SF6) SupplyChlorine SupplyOxygen SupplyHelium SupplyNitrogen SupplyPneumatics SupplyDrybox temperature control1. Gas inlet2. Jet stream column3. Reduction tank4. Neutralization tank5. Absorption column6. Fresh water f

9、eed7. Chemical feed8. Waste water discharge9. Pure gas outlet Over 90% of silica is collected to the350l jet stream tank. NaOH and Na2S2O3 solutions areautomatically added to the tank tokeep the pH in the tank between 8 and8.5 and Redox potential between -50and +200mV. The washed gas is directed to

10、Neutralization tankthrough a mist eliminator. Jet stream tank receives continuous15-40 l/h overflow from Neutralization tank.The washed gas from stage 1 isdirected to the stage 2 through a setof dampers and mist eliminator(chevron type). pH of stage 2 tank is kept between10 and 11 to ensure efficientneutralization of the HCl gas. HCl + NaOH - NaCl + H2O Cl2 + 2NaOH - NaCl + NaClO + H2O新型光纤材料与器件团队 NOVEL OPTIC FIBERS AND DEVICES TEAM谢谢！谢谢！