PROCESS FOR PRODUCING OPTICAL FIBRES

摘要

In the PCVD method glass layers are deposited on the inner wall of a glass tube by heating the tube to a temperature between 1100 DEG and 1300 DEG C., passing a reactive gas mixture at a pressure between 1 and 30 hPa through the glass tube, and moving back and forth inside the glass tube a plasma. After the glass layers are deposited, the glass tube is collapsed to produce a solid preform from which optical fibers are drawn. The regions of nonconstant deposition geometry at the ends of the preform (taper) are reduced by moving the plasma in the area of at least one reversal point nonlinearly with time and/or by changing the longitudinal extent of the plasma as a function of time. The length of the ramp is chosen to ensure an effective reduction of the end taper.