Abstract: A polymeric optical waveguide substrate includes a first region provided thereon with a polymer optical waveguide and an optical waveguide-free second region, the first and second regions being on the same substrate, wherein an adhesive layer is between the lowermost polymer layer constituting the optical waveguide in the first region and the substrate, and wherein a groove intrudes into the substrate at the boundary between the first and second regions. A method for preparing the waveguide substrate includes the steps of applying an adhesive layer onto the first region while the second region is free of any adhesive layer; applying a polymer onto the whole surface of the substrate to give a polymer layer for forming an optical waveguide following the formation of the adhesive layer; cutting the polymer layer at the boundary between the first and second regions; and peeling off or removing the polymer on the second region.

Abstract: It is a problem of disclosed technology to provide a polymer optical waveguide substrate having a V-groove for fiber alignment providing optical coupling with an optical fiber with low loss.

Abstract: A polymeric optical waveguide substrate comprises a first region provided thereon with a polymer optical waveguide and an optical waveguide-free second region, the first and second regions being present on the same substrate, wherein it comprises an adhesive layer between the lowermost polymer layer constituting the optical waveguide in the first region and the substrate, for improving the adhesion or adhesive properties of them and wherein it has a groove intruding into the substrate at the boundary between the first and second regions.

Abstract: The invention provides an optical element comprising a substrate having provided thereon a coating of an organic zirconium compound, a coating of a fluorine-free polyimide resin and a coating of a fluorine-containing polyimide resin, in this order. The element has increased adhesive property with the substrate and reliability.

Abstract: It is a problem of disclosed technology to provide a polymer optical waveguide substrate having a V-groove for fiber alignment providing optical coupling with an optical fiber with low loss.

Abstract: A method is supported for aligning the height of a polymer waveguide to the height of a core layer of a semiconductor element in an optical module composed so as to mount the semiconductor element on its polymer waveguide substrate. In order to achieve the method, at first a waveguide is formed on the silicon substrate coated with an oxide film using a polymer whose refractive index is larger than that of the oxide film. The waveguide consists of a lower cladding layer, a core layer, and an upper cladding layer. The lower cladding layer is formed to be thinner than the conventional one and the height of the core layer is set to 5 to 10 &mgr;m. In this way, it is possible to fabricate an optical module in less process steps and at a lower cost than the conventional one.