Patent ID: 8642250

Claim:
An optical waveguide, comprising: a substrate; a cladding layer provided on the substrate; and a core portion provided on the cladding layer for transmission of an optical signal; wherein the core portion is formed from a resin composition comprising: (A) a multifunctional partially-acrylated epoxy resin having a structural unit represented by the following general formula (1) as a main component, wherein epoxy groups and (meth)acrylate groups are present as photosensitive substituent groups in a number ratio of 40:60 to 60:40 based on a total number of 100 in the multifunctional partially-acrylated epoxy resin (A), wherein the total number of 100 represents 100% of a total of epoxy groups and (meth)acrylate groups present in the multifunctional partially-acrylated epoxy resin: wherein R 1 and R 2 , which may be the same or different, are each a hydrogen atom or a methyl group, wherein R 3 is a hydrogen atom or a methyl group, and wherein in the entirety of the multifunctional partially-acrylated epoxy resin (A), m+n=1, m=0.40-0.60 and n=0.60-0.40; and (B) a photopolymerization initiator system as a curing component comprising both a photoradical polymerization initiator and a photoacid generator.