Fujitsu Corporation

Fujitsu Optical Components Limited

The University of Tokyo

Koji Otsubo

Hajime Shoji

Haruhiko Kuwatsuka

Masaki Sugiyama

Tsuyoshi Yamamoto

Hiroshi Ishikawa

Kazumasa Takabayashi

Naoki Kuwata

Yasuhiko Arakawa

Nobuaki Hatori

Tetsuo Ishizaka

Manabu Matsuda

Yoshiaki Nakata

Shuntaro Makino

Tomonori Azuma

Tatsuroh Ikeda

An optical device includes an optical coupler that inputs an optical signal received from a light source, a semiconductor optical amplifier that amplifies the optical signal received from the optical coupler, and a light receiving element that receives spontaneous emission light received from the semiconductor optical amplifier. The optical coupler includes a first input port to which the optical signal received from the light source is input, a second input port that is connected to an input stage of the light receiving element and that is different from the first input, and an output port that is connected to an input stage of the semiconductor optical amplifier, and that outputs optical signal received from the first input port to the semiconductor optical amplifier. The light receiving element receives, via the output port and the second input port, spontaneous emission light received from the semiconductor optical amplifier.

Optical device, optical transmission apparatus, optical reception apparatus, and optical communication apparatus

An optical module includes: a first board having an optical component bonded thereto with an adhesive; a connection structure part rising from the first board and made of a material having lower thermal conductivity than thermal conductivity of a material of the first board; and a second board joined to the connection structure part.

Optical module

A light source device includes: a plurality of light sources that generate rays of light with different wavelengths corresponding to a plurality of target wavelengths located on a designated wavelength grid; a plurality of photodetectors that detect output powers of the plurality of light sources; a plurality of optical bandpass filters that are provided between the plurality of light sources and the plurality of photodetectors; a temperature adjustment unit that adjusts a temperature of an area around the plurality of light sources; and a processor that controls the temperature adjustment unit based on output signals of the plurality of photodetectors. Widths of passbands of the optical bandpass filters are less than a wavelength spacing in the wavelength grid.

Light source device that includes a plurality of light sources with different wavelengths and method of controlling wavelengths

A multi-wavelength light source has a laser region that includes a gain medium with a reflective end facet and two or more diffraction gratings optically connected to a second end facet opposite to the reflective end facet of the gain medium, an optical amplifier configured to amplify a laser beam emitted from the reflecting end facet of the laser region and containing multiple wavelengths, the multiple wavelengths being amplified collectively, an optical demultiplexer configured to demultiplex an amplified laser beam output from the optical amplifier, and output waveguides connected to the optical demultiplexer and configured to output light beams with the multiple wavelengths.

Multi-wavelength light source and optical module using the same

An optical transmitter includes: a plurality of laser diodes each of which outputs signal light having a wavelength that is different from a wavelength of other signal light; an optical multiplexer that is disposed adjacently to the laser diodes along a first direction, and that multiplexes the signal light output from the respective laser diodes; and a driving circuit that is disposed adjacently to the optical multiplexer along a second direction that is different from the first direction, and that drives the laser diodes. The optical multiplexer and the driving circuit are integrated.

Optical transmitter and optical receiver

An optical transmission device includes a first power monitor to monitor a first signal into which second signals with respectively different wavelengths are multiplexed so as to measure received power of the first signal; an amplifier to amplify the first signal, to generate a third signal; a driver to drive the amplifier; a demultiplexer to separate the third signal into fourth signals with the different respectively wavelengths; second power monitors each to monitor each of the fourth signals so as to measure received power of each of the fourth signals; a memory to store therein data related to gain in the amplifier, the data corresponding to each of wavelengths of the second signals, with respect to parameters which are the received power measured by the first power monitor and driving condition; and a processor to calculate power of each of the second signals.

Optical transmission device and optical transmission method

An optical waveform reshaping device, including a semiconductor optical waveguide which has an active layer, wherein: optical amplification regions and optical absorption regions are installed alternately along the semiconductor optical waveguide; one optical amplification region is set longer than the other optical amplification regions so that a desired amplification factor can be obtained when power of an input optical signal is at an ON level; a power level is maintained by the other optical amplification regions excluding the one optical amplification region and by the optical absorption regions when the power of the input optical signal is at the ON level; and when the power of the input optical signal is at an OFF level, the input optical signal is absorbed by the optical absorption regions so that a power level of an output optical signal will not be higher than the power level of the input optical signal.

Optical waveform reshaping device

A wavelength conversion system includes a Mach-Zehnder interferometer including two optical waveguides, a non-linear medium provided on one of the two optical waveguides, and a branching ratio adjuster for adjusting the branching ratio of multiplexed light produced by multiplexing signal light and pumping light so that the powers of the signal light and the pumping light which are to be emitted from the two optical waveguides are equal to each other. The multiplexed light whose branching ratio is adjusted by the branching ratio adjuster is introduced into the two optical waveguides such that the non-linear medium generates phase conjugation light of the signal light and the light guided through the one optical waveguide and the light guided through the other one of the two optical waveguides interfere with each other so that the phase conjugation light is extracted as wavelength conversion light.

Wavelength conversion system, optical integrated device and wavelength conversion method

The optical semiconductor device comprises an active layer including a plurality of quantum dot stackseach of which is formed of a plurality of quantum dot layersand a plurality of first layersalternately stacked, and a plurality of second barrier layersthicker than the first barrier layersstacked alternately with the quantum dot stacks. Thus, the quantum dot layers can be stacked with the generation of dislocations due to lattice mismatching between the substrate and the quantum dots suppressed. A number of quantum dot layers can be stacked with a desired light confinement coefficient ensured. The optical semiconductor device can have the characteristics easily improved.

Optical semiconductor device and method for fabricating the same

The optical semiconductor device comprises a lower clad layer, optical waveguide layersincluding an active layer for recombining the carriers. The upper clad layeris mesa stripe configuration having a first mesa portion contacting the contact layerand having a first width, and a second mesa portion having a second width larger than the first width. The first width, the second width and the thickness of the second mesa portion are set not to oscillate in the higher-order transverse mode.

An intrinsic GaAs waveguide layer is formed on a p-type AlGaAs cladding layer, a quantum dot active layer is formed further thereon. An n-type AlGaAs cladding layer is formed on the center portion of the quantum dot active layer. Thus-configured semiconductor laser is allowed to successfully suppress the area of the p-n junction plane to a small level, and to obtain a high level of reliability, because there is no need of processing the center portion of the quantum dot active layer, contributive to laser oscillation.

Semiconductor laser and method of fabricating the same

A surface-emitting laser has a lower multilayer film reflecting mirror, an active layer, a current confinement layer, a clad layer, an upper multilayer film reflecting mirror, and an upper electrode formed in the order described on the upper surface of a substrate having a lower electrode formed on the lower surface thereof. The current confinement layer includes a conductive part and an insulating part surrounding the conductive part with the conductive part being defined by a sidewall surface that widens along a direction toward the active layer.

Surface-emitting laser with a low threshold value and low power consumption and method of manufacturing the same

A lower multi-layer mirror is disposed on a substrate made of a first semiconductor having a first lattice constant. The lower multi-layer mirror has a lamination structure that a first layer made of an oxide of a second semiconductor and a second layer made of a third semiconductor are alternately stacked. A strain-relaxation layer is disposed on the lower multi-layer mirror, the strain-relaxation layer being made of a fourth semiconductor having a second lattice constant different from the first lattice constant. An active layer is disposed on the strain-relaxation layer. The active layer including a luminescence region is made of a fifth semiconductor having a third lattice constant different from the first and second lattice constants. An upper multi-layer mirror is disposed on the active layer. A surface-emitting semiconductor laser is provided which has a high efficiency and a low heat resistance.

Surface emitting semiconductor laser device capable of improving heat radiation efficiency and its manufacture method

A planar laser diode includes a substrate, a first multilayer structure on the substrate and formed of an alternate stacking of a first epitaxial layer and a second epitaxial layer, a cavity structure provided on the first multilayer structure and including an undoped active layer for producing optical radiation as a result of stimulated emission, a second multilayer structure provided on the cavity structure and formed of an alternate stacking of a third epitaxial layer and a fourth epitaxial layer, a first electrode structure on a bottom surface of the substrate, a second electrode structure for injecting carriers to said active layer via said cavity structure, an optical passage provided in one of the first and second electrode structures for allowing an optical beam to pass therethrough; a a current path structure provided between the second electrode structure and the active layer for providing a passage of the carriers, a current confinement structure for confining the passage of the carriers such that said carriers flow along a path generally coincident to an optical path of the optical beam, and a conductive region provided in contact with said the electrode structure for causing the carriers to flow therethrough, wherein the conductive region is provided so as to avoid the optical path.

Growing community of inventors

Kawasaki, Japan

Koji Otsubo