Hitachi, Ltd.

Hitachi, Ltd. and Hitachi Microcomputer Eng. Ltd.

Atsushi Takai

Akihiko Takase

Hajime Abe

Ryoji Takeyari

Hiroyuki Itoh

Kazuhisa Uomi

Yoshimune Hagiwara

Toshiyuki Usagawa

Terumi Sawase

Yuzo Kita

Satoshi Kaneko

Makoto Takahashi

Satoshi Aoki

Takeshi Kato

Masahiro Aoki

Kazuhiro Ito

Tatemi Ido

Shinji Sakano

Katsuyuki Imoto

Makoto Suzuki

Hirohisa Sano

Yoshihiro Takiyasu

Takaaki Hagiwara

Kazuyuki Fukuda

Misuzu Sagawa

Mitsuhiro Yamaga

Makoto Shimaoka

Hiroshi Kurokawa

Kazunori Nakamura

Shoichi Hanatani

Shoji Yamada

Koichiro Tonehira

Nagatoshi Usami

Tsutomu Yoshiya

Shigefumi Kito

Shinzo Nishiyama

Akira Honda

Atsushi Miura

An optical frequency division multiplexing network includes first optical communication paths connected to terminals, respectively, a second optical communication path connected to the outside and a node composed of a selection unit for selecting signals having optical frequencies to be sent to the plurality of terminals, respectively, from signals transmitted through the second optical communication path in optical frequency division multiplexing, a conversion unit for converting the selected signals into signals having a single optical frequency and an output unit for producing the converted signals to the terminals through the first optical communication paths, respectively.

Optical frequency division multiplexing network

An optical transmission device which is used for a short range optical data link or an optical communication system for subscribers and more particularly requires no automatic optical power control minimizes the turn-on delay time of a laser diode and allows unformatted optical signal transmission by fixed level decision receiving system. By applying a fixed-bias electric current which is not more than the electric threshold current value of the laser diode to the laser diode, the turn-on delay time of the laser diode can be minimized, and the extinction level can be lowered by it, and the fixed level decision receiving system can be used, and the optical receiver circuit can be simplified more.

Driving circuit of laser diode and optical transmission device

A parallel optical transmission device is disclosed, which comprises a transmitter section having one or a plurality of transmitter modules converting one or a plurality of input electric signals into optical signals; a section consisting of bundles of optical waveguides 20i, j transmitting the optical signals; and a receiver section having one or a plurality of receiver modules reproducing the electric signals from the optical signals thus transmitted to output them; wherein all propagation delay times from the input electric signals to the output electric signals are set in predetermined regions.

Optical parallel transmission device

An optical semiconductor array module comprising an optical semiconductor array device constituted by a plurality of semiconductor laser diode, light-emitting diode elements or a plurality of semiconductor photo diode elements, an electronic device for driving and controlling the optical semiconductor array device, a cube-shaped package case for housing the optical semiconductor array device and the electronic device therein, an optical fiber array optically coupled to the optical semiconductor array device, a supporting member for holding and fixing the optical fiber array to one surface of the cube-shaped package case, and a terminal portion having a plurality of pins for electrically connecting an external circuit board to the electronic device. The terminal portion is formed by extending the terminal portion from at least one of surfaces forming the package case, excluding a surface on which the optical semiconductor array device and the electronic device are mounted and a surface opposite to that surface, and the plurality of pins are mounted in a surface of the terminal portion which crosses at right angles with a surface from which the optical fiber array is taken out, whereby the electronic device is mounted on the external circuit board through the plurality of pins and is electrically connected to the external circuit board.

Optical semiconductor array module, method of fabricating the module,

Disclosed is a semiconductor optical integrated device and method of fabricating the device, the device having a plurality of quantum well structures, formed on a single substrate, acting as optical waveguides, the plurality of quantum well structures respectively having different lattice mismatches with the substrate and/or different strains (e.g., respectively compressive strain and tensile strain). The method includes selectively depositing the quantum well structures by, e.g., organometallic vapor phase epitaxy on growth regions of the substrate, the growth regions being defined by insulating layer patterning masks, with a width of the growth regions and/or a width of the patterning mask being different for the different quantum well structures. Each quantum well structure includes quantum well layers of III-V or II-VI compound semiconductor material, the Group III or Group II elements each including at least two elements, one having a relatively large atomic diameter and another having a relatively small atomic diameter. Also disclosed is a light receiver that can independently absorb TE-mode and TM-mode light in series, which can be used in a polarized-wave diversity receiver for coherent optical communication.

Semiconductor optical integrated device and light receiver using said

A semiconductor device may include a double hetero junction bipolar transistor and a field-effect transistor. The base of the bipolar transistor and the gate of the field-effect transistor are connected to each other to serve as an input terminal and the collector of the bipolar transistor and the drain of the field-effect transistor are connected to each other to serve as an output terminal. The bipolar transistor and the field-effect transistor may be created on a common substrate. In this case, both the bipolar and field-effect transistors can have the same multilayer/film structures.

Semiconductor device

A method of testing a DC coupled optical receiver is provided. DC light is superimposed on an optical signal, the power of DC light is changed to observe waveform at a light extinction level, and the measurement and the prediction of the bit error rate are performed. Similarly, in a multi-channel DC coupled optical receiver, DC light is applied to a channel to be observed, while signal light is applied to other channels to observe cross-talk.

Method and apparatus for testing a DC coupled optical receiver

A surface emitting semiconductor laser of a laminated structure having at least a light emitting active layer sandwiched between a dielectric film multi-layer mirror and a p-type semiconductor multi-layer mirror on a semiconductor substrate. The energy .DELTA.Ec of conduction band discontinuity is higher than the energy .DELTA.Ev of valence band discontinuity between at least two kinds of semiconductor layers with different refractive indices constituting the p-type semiconductor multi-layer mirror. On the other hand, the energy .DELTA.Ev of valence band discontinuity is higher than the energy .DELTA.Ec of conduction band discontinuity between at least two kinds of semiconductor layers with different refractive indices constituting the n-type semiconductor multi-layer mirror.

Surface emitting semiconductor laser

Growing community of inventors

Kokubunji, Japan

Atsushi Takai