Patent ID: 6044192
Filing Date: 2000-03-28
Classification: G02B

Abstract:
A cladded waveguide pair assembly obtainable by plasma enhanced chemical vapour deposition (PECVD), comprising a substrate, a buffer layer of dielectric material on said substrate, a pair of elongate dielectric waveguide cores deposited on the buffer layer and of higher refractive index than that of the buffer layer, and a cladding layer of boron and phosphorus doped silica glass (BPSG) arranged over the pair of cores and adjoining regions of the buffer layer including the interval between the cores of the pair, said BPSG cladding layer having a lower refractive index than that of the material of the cores and a lower flowing temperature than that of the materials of the cores and the buffer, wherein said BPSG cladding layer is obtainable in multiple stages each stage consisting of a PECVD deposition step and a subsequent annealing step by which the deposited material is flowed.