Fujitsu Corporation

Hideaki Koyano

Masato Kobayashi

Kazumaro Takaiwa

Akio Takayasu

Maki Hiraizumi

Kazukiyo Ogawa

Yasushi Yoshino

Tatsuru Iwaoka

Minoru Tateno

An optical signal adjustment apparatus detects an optical signal intensity level of signal light components with multiple different wavelengths for each of the wavelengths in an optical detection unit and adjusts the signal light components with the wavelengths for each of the wavelengths in a variable optical attenuator to make the optical signal intensity levels of the signal light components uniform. The apparatus includes a control unit configured to successively select a detection signal associated with each of the wavelengths from the optical detection unit and generate a control signal for the wavelength based on the selected detection signal. The control signal generated by the control unit is supplied to the variable optical attenuator associated with the selected detection signal.

Apparatus and method for adjusting optical signals

A redundant changeover apparatus causing no frame synchronization loss even upon occurrence of changeover between working system and protection system. In case of an in-apparatus synchronization system, when two input signals which are mutually asynchronous in phase are changed over by a changeover switch, a changeover switch, a clock extractor, a PLL circuit, and a clock changing portion transmit signals with clocks before the changeover being gradually changed to clocks after the changeover. Alternatively, in case of an in-apparatus synchronize system, data are separated from clocks so that the data are once changed to data with reference clocks, and then for the data, clocks before the changeover are gradually changed to clocks after the changeover.

Redundant changeover apparatus

An optical transmission device in which optical signal switching is performed to allow the device to be reduced in size and also which is capable of efficient recovery from fault, thereby improving system expansibility and communication quality. Overhead terminating section converts an optical signal to an electric signal and performs an overhead process including extraction of fault information and setting of status information. Optical switch section performs a process of switching the optical signal between active and standby lines, and switching control section provides a switching command to the optical switch section in accordance with the fault information.

Optical transmission device and optical transmission system

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Yokohama, Japan

Hideaki Koyano