Manufacturing method of optical waveguide formed on a coloured-layer -coated PET substrate and optical waveguide obtained thereby

摘要

A manufacturing method of an optical waveguide device and an optical waveguide device obtained thereby. An under cladding layer (21) is formed on the front surface of a colored-layer-coated PET substrate (A) including a PET substrate portion (1) and a colored layer (5) of a color that absorbs irradiation light and formed on the back surface of the PET substrate portion, and then a photosensitive resin layer (3A) for the formation of cores is formed thereon. In forming the cores, when the irradiation light reaches the bottom surface of the PET substrate portion, most of the irradiation light is absorbed by the colored layer, so that there is little irradiation light reflected from the bottom surface of the PET substrate portion. This significantly reduces the irradiation light reflected diffusely from the PET substrate portion and reaching the photosensitive resin layer to thereby effectively suppress the surface roughening of the side surfaces of the cores.