Fujitsu Corporation

Terukazu Naruse

Haruhiko Tabuchi

Kohei Shibata

Koji Terada

An optical device enabling reducing device scale is constituted by M circulators (), (M being a natural number), a waveguide-type diffraction grating () including M first input/output waveguides () formed at its one end and M&#xd7;N second input/output waveguides (-to-N and-to-N) formed at the other end, (N being a natural number), and paths from the M circulators being connected to the M first input/output waveguides; and N reflection-type optical switches (-to-N) each for reflecting the optical paths for M adjacent waveguides out of the M&#xd7;N second input/output waveguides(-to-N and-to-N) and for switching over the returning-destination waveguide respectively, wherein the M circulators, the waveguide-type diffraction grating and N reflection-type optical switches are arranged in cascade. Consequently, the optical device can function preferably also as a wavelength selective optical switch available in a WDM transmission system.

Wavelength selective and level adjusting optical device

An optical device used, for example, in an add/drop multiplexer, a dynamic gain equalizer or a optical power monitor. The optical device includes (a) a substrate; (b) a first slab waveguide formed on the substrate; (c) channel waveguides of differing lengths formed on the substrate, light output from the first slab waveguide being input to the channel waveguides; and (d) a second slab waveguide formed on the substrate, light output from the channel waveguides being input to the second slab waveguide. An end face of the second slab waveguide shares a face with an end face of the substrate. The optical device has low loss characteristics.

Optical device with slab waveguide and channel waveguides on substrate

An optical device enabling reducing device scale is constituted by M circulators (), (M being a natural number), a waveguide-type diffraction grating () including M first input/output waveguides () formed at its one end and M&#xd7;N second input/output waveguides (-to-N and-to-N) formed at the other end, (N being a natural number), and paths from the M circulators being connected to the M first input/output waveguides; and N reflection-type optical switches (-to-N) each for reflecting the optical paths for M adjacent waveguides out of the M&#xd7;N second input/output waveguides (-to-N and-to-N) and for switching over the returning-destination waveguide respectively, wherein the M circulators, the waveguide-type diffraction grating and N reflection-type optical switches are arranged in cascade. Consequently, the optical device can function preferably also as a wavelength selective optical switch available in a WDM transmission system.

Optical device

An optical multiplexer/demultiplexer uses a diffraction grating, capable of multiplexing/demultiplexing lights of narrow wavelength spacing at a short focal distance. To this end, a plurality of output waveguide groups is connected to one end face of a slab waveguide to which an input waveguide group is connected. A diffraction grating in which grating grooves, each including a plurality of reflection planes blazed corresponding to respective arrangement directions of the plurality of output waveguide groups are formed, is disposed on the other end face of the slab waveguide. The arrangements of the respective output waveguide groups are determined, so that diffracted lights of wavelengths different from each other, which are reflected by the reflection planes of the diffraction grating, respectively reach the output waveguides of the plurality of output waveguide groups.

Optical multiplexer/demultiplexer

The invention provides a wavelength division demultiplexing apparatus which can reduce the connection loss between an input slab and channel waveguides and can suppress excitation of higher-order mode light to reduce the loss. The apparatus includes a first waveguide for propagating WDM light, a first slab for diffusing the light from the first waveguide, a plurality of channel waveguides having a series of different waveguide lengths with a predetermined difference for receiving and splitting the light from the first slab, a second slab for condensing the split light from the channel waveguides, and a second waveguide for propagating the light from the second slab therein, all formed on asubtrate. The channel waveguides and the first slab are optically connected to each other at a number of nodes greater than the number of nodes at which the channel waveguides and the second slab are connected to each other.

Wavelength division demultiplexing apparatus

The present invention aims at providing a wavelength multiplexing/demultiplexing apparatus for reducing a loss at a portion where an input slab and channel waveguides are connected with each other, thereby capable of realizing the reduction of loss in the overall apparatus. In order to achieve the above object, in this wavelength multiplexing/demultiplexing apparatus comprising an input waveguide, an input slab, channel waveguides, an output slab and output waveguides that are formed on a substrate, a curvature radius (r1) of an output side circular arc interface of the input slab is smaller than a curvature radius (r2) of an input side circular arc interface of the output slab, and spacing (P ) between the channel waveguides at a portion where the input slab and each of the channel waveguides are connected with each other is smaller than spacing (P ) between the channel waveguides at a portion where each of the channel waveguides and the output slab are connected with each other.

Wavelength multiplexing/demultiplexing apparatus

The invention provides a wavelength division demultiplexing apparatus which can reduce the connection loss between an input slab and channel waveguides and can suppress excitation of higher-order mode light to reduce the loss. The apparatus includes a first waveguide for propagating WDM light, a first slab for diffusing the light from the first waveguide, a plurality of channel waveguides having a series of different waveguide lengths with a predetermined difference for receiving and splitting the light from the first slab, a second slab for condensing the split light from the channel waveguides, and a second waveguide for propagating the light from the second slab therein, all formed on a subtrate. The channel waveguides and the first slab are optically connected to each other at a number of nodes greater than the number of nodes at which the channel waveguides and the second slab are connected to each other.

An optical multiplexer/demultiplexer having a small-loss structure that uses an arrayed waveguide grating to optimally make the passband characteristic of demultiplexed light flat. An optical input waveguide and a sector slab waveguide are connected by a directional coupler. The directional coupler comprises a central waveguide including an end portion on the output side of the optical input waveguide and arranged waveguides which are arranged on both sides of the central waveguide and the exits of which are connected to the sector slab waveguide. A taper is formed on both side portions of the central waveguide so that the width of a core will gradually narrow in the direction of the exit, and the central waveguide is located so that this end portion will not touch the sector slab waveguide. The width of a core in each of the arranged waveguides is uniform. The arranged waveguides are arranged on both sides of the central waveguide by the same numbers so that the arranged waveguides will be parallel to the taper formed on the central waveguide. As a result, light from the central waveguide couples with the arranged waveguides.

Growing community of inventors

Kawasaki, Japan

Terukazu Naruse