An improved method of controlling rare earth incorporation in optical fiber

The process parameters involved at various stages of solution doping method for fabricating rare earth (RE) doped optical fiber have been systematically investigated to optimize the process conditions and achieve better control over RE incorporation. It is observed that the RE concentration, uniformity and the overall fiber quality are strongly influenced by the solution properties and dipping parameters. The soaking solution needs to be judiciously selected depending on the porous layer characteristics to improve the fiber quality and process efficiency. An interesting observation not hitherto reported is the influence of Al ion concentration in the solution on RE incorporation into the core. The investigation helps to obtain the optimum conditions necessary to produce fibers of given specification and achieve greater reproducibility.