Provided is a wavelength path communication node device with no collision of wave lengths and routes, capable of outputting arbitrary wavelengths, and capable of outputting them to arbitrary routes. An add/drop multiplexer (11) includes a communication unit (101) that communicates an optical signal with at least one client device and at least one network and a control unit (102) that indicates a transfer destination of the optical signal according to an attribute of the received optical signal to the communication unit (101). The control unit (102) indicates an attenuation amount of the optical signal to the communication unit (101) for each connected device. When a connected device is changed, the control unit (102) instructs the communication unit (101) to change the attenuation amount. The communication unit (101) attenuates the optical signal with the attenuation amount indicated by the control unit (102) and transfers the attenuated optical signal to a transfer destination.

A circuit having multiple inputs and multiple outputs the circuit being for switching signals received at any of the inputs to any of the outputs, the circuit comprising: a first switch matrix, the first switch matrix being capable of directing signals received at the inputs of the circuit to multiple first intermediate ports; a second switch matrix, the second switch matrix being capable of directing signals received at multiple second intermediate ports to multiple third intermediate ports, the number of the second intermediate ports being less than the number of the inputs of the circuit; one or more primary bypass links, each primary bypass link being capable of coupling one or more of the first intermediate ports to a respective one or more of the outputs of the circuit independently of the second switch matrix; a first redirection layer, the first redirection layer being capable of, for each first intermediate port, directing a signal received at that first intermediate port to a primary bypass link or to a second intermediate port; and a second redirection layer, the second redirection layer being capable of directing signals received at each of the primary bypass links to a respective one or more outputs of the circuit, and directing signals received at each of the third intermediate ports to a respective one or more outputs of the circuit.

An optical switch is proposed, for routing an optical transmission signal according to an optical control signal, including one or more optical control ports; three or more optical transmission ports; a light director; and a thermally driven light mill; where the light mill and the light director are arranged with respect to each other, to the one or more control ports and to the three or more transmission ports such that: illumination of a respective one of the one or more control ports by a control beam carrying the control signal drives the light mill to rotate towards a respective position in which the light director is arranged so as to direct a transmission beam carrying the transmission signal, entering the switch via a respective one of the transmission ports, to exit the switch via a respective other of the transmission ports.

A thyristor switch is constituted of a pair of arms connected in anti-parallel, each of the anus including a plurality of thyristors connected in series. A controller includes a phase detecting unit configured to detect a phase of a power supply voltage supplied from an alternating-current power supply, and a gate signal generating unit configured to interrupt a gate signal when an open command is provided to the static switch and the phase of the power supply voltage detected by the phase detecting unit matches a target phase. The target phase is set outside of a phase range where interruption of the gate signal is prohibited, the phase range being set so as to include a zero crossing point at which a load current is switched in polarity.

A thyristor switch is constituted of a pair of arms connected in anti-parallel, each of the anus including a plurality of thyristors connected in series. A controller includes a phase detecting unit configured to detect a phase of a power supply voltage supplied from an alternating-current power supply, and a gate signal generating unit configured to interrupt a gate signal when an open command is provided to the static switch and the phase of the power supply voltage detected by the phase detecting unit matches a target phase. The target phase is set outside of a phase range where interruption of the gate signal is prohibited, the phase range being set so as to include a zero crossing point at which a load current is switched in polarity.

A cascadable AGC amplifier in a signal distribution system includes a low noise cascadable amplifier having a through path and a cascadable output. The cascadable amplifier is also configured to provide AGC over a predetermined input power range. The cascadable AGC amplifier can be configured to provide gain or attenuation. When the cascadable AGC amplifier is implemented in a signal distribution system, typically as part of a signal distribution device, an input signal can be gain controlled and supplied to multiple signal paths without distortion due to degradation of signal to noise ratio or distortion due to higher order amplifier products. The distributed signal is not significantly degraded by distortion regardless of the number of cascadable AGC amplifiers connected in series or the position of the cascadable AGC amplifier in the signal distribution system.

A large number of degrees for relays of optical signals transmitted via optical paths in the degrees is secured. A wavelength cross-connect device 20A performs a relay by splitting optical signals from respective degrees indicated by reference numerals 40l, 40h, 40m, 40q, each of the degrees being provided by optical fibers, via respective optical couplers and outputting the split optical signals to output sides of the plurality of degrees via respective WSSs 23a to 23d. As the optical couplers, variable couplers 27a to 27d whose respective splitting ratios, each of which is a ratio of optical signal power losses in splitting an optical signal, are variable are used. The wavelength cross-connect device 20A includes a control unit 26 that performs control to change the splitting ratios in such a manner as to eliminate an imbalance among OSNR margins of the output sides of the degrees in which a plurality of optical paths transmitting the split optical signals extend. The control unit 26 calculates the margins for the respective optical paths transmitting the split optical signals via the variable couplers 27a to 27d, for each of the output sides of the degrees. The control unit 26 performs control to, based on respective smallest margins of the degrees in all the margins, change the splitting ratios of the variable couplers 27a to 27d in such a manner as to eliminate an imbalance between the margins of the degrees.

Provided is a wavelength path communication node device with no collision of wavelengths and routes, capable of outputting arbitrary wavelengths, and capable of outputting them to arbitrary routes. An add/drop multiplexer (11) includes a communication unit (101) that communicates an optical signal with at least one client device and at least one network and a control unit (102) that indicates a transfer destination of the optical signal according to an attribute of the received optical signal to the communication unit (101). The control unit (102) indicates an attenuation amount of the optical signal to the communication unit (101) for each connected device. When a connected device is changed, the control unit (102) instructs the communication unit (101) to change the attenuation amount. The communication unit (101) attenuates the optical signal with the attenuation amount indicated by the control unit (102) and transfers the attenuated optical signal to a transfer destination.

Provided is a wavelength path communication node device with no collision of wavelengths and routes, capable of outputting arbitrary wavelengths, and capable of outputting them to arbitrary routes. An add/drop multiplexer (11) includes a communication unit (101) that communicates an optical signal with at least one client device and at least one network and a control unit (102) that indicates a transfer destination of the optical signal according to an attribute of the received optical signal to the communication unit (101). The control unit (102) indicates an attenuation amount of the optical signal to the communication unit (101) for each connected device. When a connected device is changed, the control unit (102) instructs the communication unit (101) to change the attenuation amount. The communication unit (101) attenuates the optical signal with the attenuation amount indicated by the control unit (102) and transfers the attenuated optical signal to a transfer destination.

An optical add-drop apparatus dropping a signal in input optical fibers in an optical cross-connect apparatus or adding a signal into output optical fibers from the cross-connect apparatus, optical cross-connect portions of the cross-connect apparatus connected such that a cross-connect portion internal connection output port is directly connected to an internal connection input port of another cross-connect portion and is indirectly connected via the other cross-connect portion to an internal connection output port of a further cross-connect portion, the add-drop apparatus having: photocouplers connected to part or all of the input fibers connected to each cross-connect portion; and drop signal receiving apparatuses each having optical switches each receiving and alternately selecting a signal output from photocouplers connected to respective different cross-connect portions of the cross-connect portions out of the photocouplers, the drop signal receiving apparatuses selecting a signal of a wavelength for each signal respectively output from the optical switches.