Hitachi Cable, Inc.

Kimio Inaba

Kenji Akiba

Akiji Shibata

Masayuki Hosono

Kenichi Morosawa

A multilayer semiconductor device has plural semiconductor devices, each having a circuit board for a ball grid array and a semiconductor chip provided on the board. The semiconductor boards are bonded together by a reflow mounting process to use a solder ball for interlayer connection so as to form a multilayer structure. The plural semiconductor devices each have a projection for restricting inclination of the circuit board, and the projection is provided between neighboring two of the circuit boards.

Multilayer semiconductor device

Plurality of channel waveguides of an arrayed waveguide diffraction grating are arranged such that all of intervals thereof are not constant between each two adjacent channel waveguides at a first coupling portion for coupling an input slub waveguide and the arrayed waveguide diffraction grating and a second coupling portion for coupling an output slub waveguide and the arrayed waveguide diffraction grating. Further, the plurality of channel waveguides of the arrayed waveguide diffraction grating are arranged such that all of length differences thereof are not constant between each two adjacent channel waveguides. For example, one of the channel waveguides is deleted, so that a length difference of adjacent channel waveguides is determined to be larger than that of the other two adjacent waveguides. According to this structure, it is possible to provide an optical waveguide multiplexer/demultiplexer in which an insertion loss property becomes flat in all wavelength ranges and the insertion loss characteristics are not fluctuated by the fluctuation of the wavelength.

Optical wavelength multiplexer/demultiplexer

An optical wavelength multiplexer/demultiplexer has an input channel waveguide, an input slab waveguide, an arrayed-waveguide grating having N channel waveguides, an output slab waveguide, and N output channel waveguides. Each output channel waveguide is provided with an outwardly tapered end. Each tapered end has a width at its end surface which becomes larger as the output channel waveguide becomes distant from the symmetrical axis of the output slab waveguide. The loss differences suffered by each separated signal may be substantially reduced.

Provision of a predetermined number of artificial waveguides having a predetermined core width along a plurality of channel waveguides on both sides of an array waveguide diffraction grating can reduce a variation and fluctuation in core width, improving crosstalk characteristics.

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Hitachi, Japan

Kimio Inaba