Fujitsu Corporation

Susumu Yamazaki

Shinsuke Tanaka

Ken Morito

Masahiro Kobayashi

Takuya Fujii

Haruhisa Soda

Chikashi Anayama

Akito Kuramata

Toru Uchida

Kazuo Nakajima

Takao Kaneda

Takashi Mikawa

Hirohide Kurakake

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 group III-V compound semiconductor laser of a 1 .mu.m band having an excellent conversion efficiency and a high characteristic temperature. The semiconductor laser can emit light in a 1.3 .mu.m band or a 1.55 .mu.m, and has a laser structure including an active layer For emitting light, guide layers sandwiching the active layer and having a band gap larger than the active layer, and clad layers embracing the guide layers and having a band gap larger than the guide layers. The lattice constants of the guide layers and clad layers are larger than a1 by 0.5% or more and smaller than a2 by 0.5% or more, where a1 represents the lattice constant of GaAs and a2 is the lattice constant of InP.

Semiconductor laser

An apparatus for growing a compound semiconductor layer by metal organic chemical vapor deposition (MOCVD) is disclosed. Utilizing the apparatus, the semiconductor layer of uniform thickness and uniform composition can be grown. The apparatus includes a plurality of vent pipes which spout a mixed gas of source material gases and a dilution gas into a reactor chamber, vertical to a substrate surface. The apparatus also includes a gas supply system in which a gas flow rate through each vent pipe is made to be controllable individually by a flow controlling device. In addition, a controller is operatively connected to the flow controlling devices, so that automatic growth of a semiconductor layer of a high quality can be achieved. When two source material gases used are mutually too reactive and deposits are formed within the gas supply system, two separate gas supply systems for these two gases are demonstrated to be effective. Another embodiment which enables individual control of concentration of the source material gas and the gas flow rate through each vent pipe, is also disclosed.

Metal organic chemical vapor deposition method with controlled gas flow

A buried structure avalanche multiplication photodiode (APD) is provided with a surface level difference between the multiplication region and guard ring region. The APD has a so-called separated absorption and multiplication region structure comprising an n-InGaAs light absorbing layer and an n-InP multiplication layer. The surface level difference is provided by selective growth of the layer in which the guard ring is formed or selective removal of the layer over the multiplication region. In the APD, the pn junction is level throughout the multiplication region and guard ring region or is made farther apart from the light absorbing layer in the guard ring region than in the multiplication region, and a significant reduction of dark current due to tunneling current in the InGaAs layer and/or InGaAsP layer is obtained. Moreover, the breakdown voltage difference of the pn junction in the multiplication region and the guard ring region has also been increased.

Growing community of inventors

Kawasaki, Japan

Susumu Yamazaki