Hitachi Cable, Inc.

Kenji Akiba

Kimio Inaba

Kenichi Morosawa

Hisato Uetsuka

Morihiko Ikegaya

Hideaki Arai

At least one input waveguide, plural output waveguides, an arrayed waveguide diffraction grating composed of plural channel waveguides successively extending in a length by &Dgr;L, an input slab waveguide for connecting the input waveguide with the arrayed waveguide diffraction grating, and an output slab waveguide for connecting the arrayed waveguide diffraction grating with the output waveguides are respectively formed on a substrate. An interval between central axes of the adjacent channel waveguides composing the arrayed waveguide diffraction grating slowly varies through the whole channel waveguides on one or both of the input and output ends of the arrayed waveguide diffraction grating.

Multiplexer/demultiplexer for WDM optical signals

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.

Optical multiplexer/demultiplexer

An optical wavelength multiplexer/demultiplexer has an input channel waveguide for receiving a wavelength division multiplexed signal, a first slab waveguide having an input boundary and a fan-shaped output boundary, an arrayed-waveguide grating comprising N channel waveguides, which provides a predetermined waveguide length difference from each other, a second slab waveguide having a fan-shaped input boundary and an output boundary, N output channel waveguides for each receiving a demultiplexed optical signals having a desired wavelength .lambda.1, .lambda.2, . . . or .lambda.n. The channel waveguides of the arrayed-waveguide grating are arranged along the fan-shaped output boundary of the first slab waveguide such that an angle .theta. between the central axis of 'i'th (i=1, 2, . . . N) channel waveguide and the symmetric axis of the fan-shaped output boundary of the first slab waveguide 4 satisfies the certain equations.

An optical device having a switching function has a waveguide filter for switching whether input signal light of including at least one specific wavelength should be transmitted or reflected. The input signal lights of wavelength of .lambda..sub.1 .about..lambda.n are transmitted to the input waveguide. When the waveguide filter is off, the signal lights of all wavelength are transmitted to the output port. When the waveguide filter is on, the signal light of wavelength of .lambda..sub.2 .about..lambda.n are transmitted, but the signal light of wavelength of .lambda..sub.2 is reversed and output to the drop port. If the thin film heaters are off, a signal light of wavelength of .lambda..sub.1 is output (dropped) from the drop port. If the thin film heaters are on, it is reversed and transmitted to the output port.

Growing community of inventors

Fukushima, Japan

Kenji Akiba