A technique for making low-loss fused silica core-borosilicate clad fiber optical waveguides

A technique for producing low-loss fused silica core-borosilicate clad fiber optical waveguides is described. The method consists of depositing radially oriented needles of borosilica on the outside surface of a fire-polished fused silica rod. This deposition is accomplished by a flame reaction of boron and silicon hydrides with oxygen. The deposit is subsequently sintered at approximately 1000°C to form a bubble free glass cladding. A thin fused silica outer jacket is then developed on this cladding to enhance the strength and the composite structure is drawn down to a fiber.