Abstract: A wavelength division multiplexing optical device includes a cladding layer formed on a waveguide substrate, a first optical waveguide embedded in the cladding layer, a second optical waveguide embedded in the cladding layer and connected at one end thereof to an intermediate portion of the first optical waveguide, and an insertion groove formed in the waveguide substrate and the cladding layer so as to extend across a connected portion of the first and second optical waveguides. The wavelength division multiplexing optical device further includes first and second wide grooves formed in the cladding layer so as to cover opposite end portions of the insertion groove and open to the opposite side surfaces of the cladding layer, and a wavelength selecting filter inserted in the insertion groove.

Abstract: An optical transmission terminal device including a printed wiring board and an optical module mounted on the printed wiring board. The optical module includes an optical component mounting substrate, a photoelectric converter mounted on the substrate, a first optical fiber having one end optically coupled to the photoelectric converter, and a ferrule mounted on the substrate so as to partially project from the substrate. The other end portion of the first optical fiber is inserted and fixed in the ferrule. A wiring pattern formed on the printed wiring board and a feed electrode formed on the substrate are connected together by wire bonding. An optically coupled portion between the photoelectric converter and the first optical fiber and a connected portion between the wiring pattern and the feed electrode are commonly covered with a transparent resin.