GRADED INDEX CLAD FUSED SILICA CORE FIBER OPTICAL WAVEGUIDES

Recently, methods of making low loss fused silica core borosilicate(1-3) clad fibers have been reported. One of these processes(3) has been to deposit a layer of borosilica onto the surface of a solid silica core rod by a flame reaction of boron and silicon hydrides with oxygen. The deposit is subsequently heat treated to form a bubble free glass cladding. The preform is then drawn into a fiber that has a step refractive index profile. Such fibers are useful, but they have a limited bandwidth when compared with fibers that have properly graded refractive index profiles. By a relatively minor modification to the above process, fibers with a partially graded index profile have now been made having a loss of 9db'km at 0.8μ wavelength.