Patent ID: 7283715

Claim:
An optical waveguide comprising a substrate, a lower clad layer on the substrate, a core layer on the lower clad layer and an upper clad layer on the core layer, at least one of the lower clad layer, the core layer and the upper clad layer is a cured product of a photo-curable organopolysiloxane composition comprising (A) a (meth)acryloyloxy group-containing organopolysiloxane of the following average compositional formula (1): (CH 2 ═CR 1 COO(CH 2 ) n ) a (Ph) b R 2 c (R 3 O) d SiO (4-a-b-c-d)/2 (1) wherein R 1 is hydrogen or methyl, R 2 is an C 1 –C 8 alkyl or C 2 –C 8 alkenyl group, Ph is phenyl, R 3 is hydrogen or an unsubstituted or alkoxy-substituted C 1 –C 4 alkyl group, subscripts a, b, c and d are numbers satisfying: 0.05≦a≦0.9, 0.1≦b≦0.9, 0≦c≦0.2, 0≦d≦0.5, and 0.8≦a+b+c+d ≦1.5, and n is an integer of 2 to 5, and having a weight average molecular weight of 1,000 to 100,000 as measured by GPC using a polystyrene standard, and (B) a photosensitizer.