Theoretical Investigation of Metal Coating Deposition on Optical Fibers by Freezing Technique. The Model of the Process

Abstract

Metal-coated fibers are irreplaceable in a multiplicity of uses owing to high hermeticity of the coating and its chemical and thermal stability. At present, the most widespread technique for the metal coating application onto a fiber is a so-called freezing technique, which consists in pulling a silica fiber through a layer of a metal's melt directly in the fiber drawing process. If the fiber temperature is lower than the metal melting point, a certain amount of the melt is frozen on the fiber surface in the form of coating. For this to occur, it is necessary that the duration of the fiber-melt contact did not exceed the time during which the fiber heats up to the metal's melting point; otherwise, the frozen metal will melt again. Because silica glass is poorly wetted with a majority of liquid metals, the coating in the latter case is likely to become discontinuous.