Hitachi, Ltd.

Sunao Kakizaki

Hideaki Tsushima

Yasuyuki Fukashiro

Shigeki Kitajima

Takashi Mori

Yukio Hayashi

Shinichi Kuwano

Masahiro Takatori

Hideaki Tushima

Sigeki Kitajima

A method is provided for detecting an optical reflection position in an optical switching unit by using a measuring system. Multiple switching commands are provided in order to direct a test light to an input port and an output port of the optical switching unit. Status information regarding the internal path of the test light is stored in a memory, along with flags corresponding to the magnitude of reflected light generated when the test light is reflected from an abnormal position along the internal path selected. The status information is stored in the form of a reflection alarm information table where the flags are stored in association with each of the internal paths. A rearmost connection among the optical interconnections in the optical switching unit is detected as an abnormal position based on the reflection alarm information table and the interconnection control table.

Optical switching apparatus with optical reflection monitor and reflection monitoring system

An optical communication network system is disclosed, which includes an optical switching apparatus. The optical switching apparatus includes an optical switch for switching and setting routes of an optical signal without being converted, a control unit for instructing the optical switch to execute a route switching operation, and a performance monitor for detecting performance of the optical signal having a route set by the optical switch. The performance monitor issues an alarm when the performance detected is deteriorated from predetermined performance. The control unit includes an alarm masking unit for masking the alarm issued from the performance monitor at least for a predetermined masking period from a starting time of a switching operation by the optical switch, and thus preventing the alarm from being issued.

Optical switching apparatus and optical communication network system

In an optical switching apparatus having redundantly-arranged optical switches, a route switching operation mode, an autonomic redundant switching operation mode and a compulsory redundant switching operation mode are discriminated from one another so that these operation modes are prevented from being executed at the same time, and also proper mask processing is performed at every switching operation mode. Therefore, emission of an undesired alarm and thus occurrence of malfunction when each switching operation is carried out can be prevented.

Optical switching apparatus, optical transmission system and method of setting up for optical signal route

An optical one-to-one protection switching apparatus exchanges signals between a transmit node and a receive node. If a fault is detected in the first transmission line (down-stream), a controller in the node controls a drive circuit so as to shut off a gate. Then, the controller in the transmit node upon receiving a switching request from the receive node, controls the drive circuit so as to shut off the gate. Thereby, the optical switch is switched. The transmitter of the client terminal is thus connected to the second transmission line (down-stream). Upon receiving the switching request from the transmit node, the optical switch in the receive node is switched. Thereby the receiver in the client terminal is connected to the second transmission line (down-stream).

Optical one-to-one protection switching apparatus

Variable (coupling ratio) optical couplers - and - each have ports of two inputs and two outputs, and the coupling ratio of inputted light is variably controlled by drive circuits - and - In the optical 1&plus;1 switching structure, the coupling ratio of the variable (coupling ratio) optical coupler - is controlled to be 50%:50%. The variable (coupling ratio) optical coupler - is controlled to have the coupling ratio of 100%:0% or 0%:100%. In the optical 1:1 switching structure, the coupling ratios of the variable (coupling ratio) optical couplers - and - are controlled to be 100%:0% or 0%:100%. When a performance monitor ( ) - detects signal degradation, signal interruption, and the like, the system controller - sends an instruction signal and the control circuits - and - output control signals for controlling coupling ratios of the variable (coupling ratio) optical couplers - and - respectively.

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Kawasaki, Japan

Sunao Kakizaki