Thermal Expanded Core Experiment of Highly Ge-Doped Single-Mode Optical Fiber
The highly doped germanium single-mode optical fibers have excellent bending resistance and high nonlinearity.Due to the mismatch of the mode field diameter to conventional G.652 fibers,the connection loss increases.To improve mode field matching,H2-O2 flame is used to expand the core of highly doped germanium optical fiber.The experiment results show that the expansion of the fiber core is not significant in the initial stage of heat treatment;with the increase of heat treatment time,the rate of fiber core expansion increases after 120 seconds of heat treatment;the expansion rate of the fiber core decreases in the later stage of heat treatment.After 4 minutes of heat treatment,the core diameter of highly doped germanium single-mode optical fiber is close to that of G.652 optical fiber,which is of great significance for improving the connection performance of the two types of fibers.