Fujitsu Corporation

The University of Tokyo

Ken Morito

Shinsuke Tanaka

Kazumasa Takabayashi

Akinori Hayakawa

Yuji Kotaki

Susumu Yamazaki

Hiroshi Onaka

Tadao Nakazawa

Naoki Hashimoto

Martin Bouda

Yasuhiko Arakawa

Kenichi Kawaguchi

Haruhiko Kuwatsuka

Hiroji Ebe

Yoshihiro Sato

Norihiko Sekine

Martin c/o Fujitsu Limited Bouda

An optical amplification control apparatus is formed from a semiconductor optical amplifier, a temperature adjustment unit adjusting the temperature of the semiconductor optical amplifier, and an optical gain control unit adjusting the temperature of the semiconductor optical amplifier by controlling the temperature adjustment unit, and varying an optical gain of the semiconductor optical amplifier. Thus, a pattern effect is suppressed even if the output light intensity (the intensity of amplified light) is increased.

Optical amplification control apparatus

Objects are achieved by an optical semiconductor device comprising: a structureincluding a substrate, a diffraction grating, an active layerand a refractive index control layer; and an laser elementincluding an electrodefor the active layer, an electrodefor the refractive index control layer and an electrodefor switching, wherein a pre-bias current is previously supplied from the electrodefor the active layer to the active layerin a state where a switching current is not supplied from the electrodefor switching to the active layer, and then while a current Ifor activation is supplied from the electrodefor the active layer to the active layer, the laser elementis turned on by supplying the switching current Ifrom the electrodefor switching to a part of the active layer, as well as turning off the laser elementby halting the supply of the switching current I.

Optical semiconductor device and driving method thereof

A polarization-independent SOA is provided which uses an InP substrate () as a semiconductor substrate and uses GaInNAs having introduced tensile strain as an active layer (). With this configuration, the polarization independence is achieved by introducing the tensile strain, and high saturation optical output power is realized by reducing the film thickness of the active layer () as well as the gain peak wavelength is increased by reducing the band gap of the active layer () through use of GaInNAs made by adding nitrogen (N) to GaInAs as a material of the active layer () so as to achieve high gain especially in C-band and L-band even when band filling exits at the time of injecting a high current into the active layer ().

Semiconductor optical amplifier

A polarization-independent SOA having an InP substrate used as a semiconductor substrate, and an active layer taking an MQW structure formed of a barrier layer made of GaInAs with tensile strain applied thereto and a well layer made of GaInNAs with no strain applied thereto alternately laminated in a plurality of layers, here, four layers of the well layer and five layers of the barrier layer are alternately laminated, is proposed.

Semiconductor optical amplifying device, semiconductor optical amplifying system and semiconductor optical integrated element

A quantum dot semiconductor device includes an active layer having a plurality of quantum dot layers each including a composite quantum dot formed by stacking a plurality of quantum dots and a side barrier layer formed in contact with a side face of the composite quantum dot. The stack number of the quantum dots and the magnitude of strain of the side barrier layer from which each of the quantum dot layers is formed are set so that a gain spectrum of the active layer has a flat gain bandwidth corresponding to a shift amount of the gain spectrum within a desired operation temperature range.

Quantum dot semiconductor device

A semiconductor optical amplification device is disclosed that has a gain spectrum of a wide bandwidth. The semiconductor optical amplification device includes an InP substrate and an active layer on the InP substrate. The active layer has a quantum well structure formed by alternately stacking a barrier layer and a well layer, the barrier layer is formed from a tensile-strained InGaAs film, and the well layer is formed from a compressively-strained InGaAs film.

Semiconductor optical amplification device and optical integrated circuit

In order to make it possible to suppress the influence of reflected light on a connection interface easily and with certainty, an optical waveguide device includes a first optical waveguide (), a second optical waveguide () formed from a material or in a structure different from that of the first optical waveguide () and connected to the first optical waveguide (), and a 1&#xd7;1 multimode interference waveguide () formed by increasing the widths of the first optical waveguide () and the second optical waveguide () in the proximity of a connection interface between the first optical waveguide () and the second optical waveguide ().

Optical waveguide device and semiconductor device

A semiconductor optical amplifier, an acousto-optic tunable filter, a phase shifter, a lens, and an internal etalon are arranged in a resonator. Outside the resonator, two lenses, two beam splitters, two photo-detectors, and an external etalon are arranged. The internal etalon is a quartz etalon and the external etalon is a crystal etalon. Therefore, the rate of change in transmission peak wavelength of the internal etalon to a temperature change is greater than that of the external etalon.

Wavelength tunable laser device

An optical integrated device includes a plurality of input optical waveguides connected respectively to a plurality of input ports provided on one end face of the optical integrated device, a single output optical waveguide connected to an output port, an optical coupler for optically coupling signal lights propagated along the plural input optical waveguides to the single output optical waveguide, and a semiconductor optical amplifier gate array formed from a plurality of semiconductor optical amplifiers provided on the input optical waveguides, respectively, and each having an electrode on the surface thereof. The optical integrated device further includes a plurality of signal lines formed on the surface of the optical integrated device in such a manner as to extend from the electrodes to an end face of the optical integrated device on which none of the input ports and the output port is provided.

Optical integrated device and optical module

A wavelength tunable laser device includes: a pair of reflection mirrors; a semiconductor element disposed between the pair of reflection mirrors, the semiconductor element integrating a region for providing an optical gain, a region having a wavelength tunable filter function and a phase control region; and an optical filter disposed between the semiconductor element and one of the pair of reflection mirrors, the optical filter having periodical transmission wavelengths. A wavelength tunable laser device is provided which is easy to be controlled and can be made compact.

Wavelength tunable laser of small size

The optical amplifying device comprises a DFB laserformed on an n type InP substrate, for outputting control light; a symmetrical Mach-Zehnder interferometerformed on the n type InP substrateand including 3 dB optical couplershaving 2 input ports and 2 output ports, and optical waveguideswhich optically interconnect the output port of the 3 dB optical couplerand the input port of the 3 dB optical coupler; and SOAsrespectively formed in the optical waveguides

Optical amplifying device

There is provided a phase control portion for controlling phase of a laser beam resonated in a resonator based on detected results by two optical detectors. The phase control portion adjusts the longitudinal mode positions by a feedback control so that a ratio of intensities detected by the two optical detectors comes to a predetermined reference value. To one of the optical detectors, part of a laser beam outputted from the resonator is irradiated as it is, whereas, to the other one of the optical detectors, part of the laser beam outputted from the resonator is irradiated after passing through an etalon. An FSR of the etalon is a double of that of another etalon in the resonator.

Wavelength tunable laser and method of controlling the same

A light oscillation part including an active layer for generating light by current injection, a tuning layer with an intermediate layer formed between the active layer and the tuning layer, for varying an oscillation wavelength by current injection and a diffraction grating formed near the active layer and the tuning layer, and a light amplification part including an active layer for amplifying light by current injection are formed on a semiconductor substrate. Light oscillation elements having wide wavelength variation ranges and the light amplification are integrated on a semiconductor substrate, whereby wide wavelength variation ranges can be obtained and the output light can be much increased.

Tunable wavelength laser

In order to realize continuous gain control while realizing polarization independent amplifying characteristic, an optical amplifying device is configured to include: a Mach-Zehnder interferometer including an input side coupler, an output side coupler and a pair of arms, that connects the input side coupler to the output side coupler; a first and a second optical amplifier, to amplify signal light, which are disposed on the pair of arms respectively; and a light source for control light to output control light, in which the first and the second optical amplifier are configured to have polarization independent characteristic and the light source for control light is configured to have a predetermined polarization dependent gain difference or a predetermined polarization dependent loss difference.

Growing community of inventors

Kawasaki, Japan

Ken Morito