Nec Corporation

Daisuke Uehara

Tsutomu Tajima

Naoya Shiota

The transponder includes a 64B/66B code synchronization bit determination circuitfor notifying a PLL selection control circuit of a control signal which instructs on selection of a variable oscillator or a variable oscillator in response to a case where an electric signal sent from an optical signal reception unitincludes a 64B/66B code synchronization bit, an A1A2 byte determination circuitfor notifying the PLL selection control circuit of a control signal which instructs on selection of a variable oscillator or a variable oscillator in response to a case where an electric signal sent from the optical signal reception unitincludes an A1A2 byte, and the PLL selection control circuitfor controlling a PLL selectorand a PLL selectorbased on a control signal.

Transponder, transmission system, transmission method and transmission program

An optical transmission system having an optical surge suppression function, includes optical amplifiers for amplifying input signal light directly, and a dummy light output unit for inputting dummy light different from the signal light into the optical amplifiers. The optical amplifiers each include a rare each element doped optical fiber for amplifying input signal light to output the amplified signal light, a pumping light source for outputting pumping light, a first optical wavelength multiplexer for inputting the pumping light to the rare earth element doped optical fiber, an optical branching device for branching part of the amplified signal light to output the branched signal light, and a pumping light control unit for controlling the output of the pumping light based on the output level of the branched light.

Optical transmission system having an optical surge suppression function

An optical ADM apparatus ( ) receives a WDM optical signal comprising first through n-th main signal components (&lgr; n) and a monitor/control signal component (&lgr;sv). A monitor/control signal terminator ( ) terminates the monitor/control signal component to produce first through n-th monitor/control signals. When a destination node ID represented by one of the first through the n-th monitor/control signals is coincident with an ID of the optical ADM apparatus ( ), the monitor/control signal processor ( ) produces a specifying signal specifying, as a specified main signal component, one of the first through the n-th main signal components (&lgr; n) that corresponds to the above-mentioned one of the first through the n-th monitor/control signals. The monitor/control signal processor ( ) further produces the first through the n-th monitor/control signals in which an origination node ID corresponding to the specified main signal component is rewritten into the ID of the optical ADM apparatus ( ) while the destination node ID corresponding to the specified main signal component is rewritten into an ID of a different node. When the specified signal is supplied from the monitor/control signal processor ( ), an ADM unit ( ) drops or separates the specified main signal component alone from the first through the n-th main signal components to output the specified main signal component.

Optical ADM apparatus and an ADM optical transmission system including the optical ADM apparatus

A wavelength division multiplexing (WDM) optical transmission system includes a node having a wavelength-demultiplexer, an optical switch connected to the demultiplexer, a regenerative repeater circuit connected to the switch, a controller, a monitor signal generator, and an output circuit. The demultiplexer receives a plurality of optical signals of different wavelengths and a first monitor signal having information indicative of bit rates of the optical signals. The controller identifies an optical signal which requires regenerative repeating based on the first monitor. The controller then outputs a first control signal to the switch for switching the optical signal into the regenerative repeater circuit. A second control signal is then output to the repeater circuit for controlling regenerative repeating based on the information indicative of the bit rate of the optical signal included in the first monitor signal. The monitor signal generator then generates a second monitor signal which includes information indicating bit rates of the optical signals including the repeated optical signal and the fact that one of the optical signals has been regeneratively repeated. The optical signal and second monitor signal are then output to another circuit which, for example, may be another node in the WDM transmission system.

WDM optical transmission system

A wavelength division multiplexing (WDM) optical transmission system includes a node having a wavelength-demultiplexer, an optical switch connected to the demultiplexer, a regenerative repeater circuit connected to the switch, a controller, a monitor signal generator, and an output circuit. The demultiplexer receives a plurality of optical signals of different wavelengths and a first monitor signal having information indicative of bit rates of the optical signals. The controller identifies an optical signal which requires regenerative repeating based on the first monitor. The controller then outputs a first control signal to the switch for switching the optical signal into the regenerative repeater circuit. A second control signal is then output to the repeater circuit for controlling regenerative repeating based on the information indicative of the bit rate of the optical signal included in the first monitor signal. The monitor signal generator then generates a second monitor signal which includes information indicating bit rates of the optical signals including the repeated optical signal and the face that one of the optical signals has ben regeneratively repeated. The optical signal and second monitor signal are then output to another circuit which, for example, may be another node in the WDM transmission system.

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Tokyo, Japan

Daisuke Uehara