It is difficult to flatten the gain profile of an optical amplifier without increasing the power consumption, the cost, and the size of the optical amplifier; therefore, a monitoring apparatus for optical amplifier according to an exemplary aspect of the invention includes an optical filtering means for receiving a monitor light beam of the optical amplifier and transmitting a filtered monitor light beam with a set range of wavelength band; a photoelectric conversion means for converting the filtered monitor light beam into a monitoring signal; and a spectrum information generating means for generating spectrum information based on the monitoring signal, the spectrum information including information on a spectrum profile of output of the optical amplifier.

In order to improve reception sensitivity of a response signal at a terminal station, an optical transmission device includes a reception unit that receives a control signal including a predetermined instruction and a main signal, via an optical transmission path connected to the terminal station, a control unit that performs the predetermined instruction of the received control signal, an extraction unit that extracts light in a band of the control signal, a response signal generation unit that modulates the extracted light in the band of the control signal, and outputs a response signal, and a multiplexing unit that multiplexes and outputs the response signal and the main signal. The control unit controls modulation by the response signal generation unit according to the control signal.

In order to provide an optical transmission device capable of implementing the spectral control of WDM signals while taking into account optical component characteristics, an optical transmission device is provided with: a WSS; a wavelength monitor that outputs a signal expressing a first spectrum, which is the spectrum of the WSS optical output; an optical processing unit that subjects the WSS optical output to prescribed processing; a temperature monitor that outputs a signal indicating the temperature of an optical processing means; and a control unit that receives the input of the signal expressing the first spectrum and the signal indicating the temperature, and controls the transmission characteristics of the WSS on the basis of the first spectrum and the temperature.

Provided is a technology for simultaneously monitoring a plurality of relay devices. A relay device 1 comprises a superimposing unit 2 and a monitor unit 3. The relay device 1 is interposed on an optical transmission path between optical communication devices that send and receive an optical signal, and has a function for relaying the optical signal flowing through the optical transmission path. The monitor unit 3 monitors the operation status of the relay device 1. At a predetermined timing, the superimposing unit 2 superimposes monitor unit 3 monitoring-information onto an optical signal of a primary signal flowing through the optical transmission path, by performing modulation processing on the basis of an oscillation signal having a predetermined oscillation frequency. The relay device 1 can spontaneously superimpose the monitoring information onto an optical signal and transmit same.

A signal detection circuit has a first differential amplifier including a first input coupled for receiving a data signal, and a second input coupled for receiving a threshold signal. A current steering circuit is coupled to an output of the first differential amplifier to establish a threshold for the first differential amplifier. A latch has an input coupled to the output of the first differential amplifier for latching a signal detect. A second amplifier has an input coupled to the output of the first differential amplifier and an output coupled to the input of the latch. A third amplifier has an input coupled to the output of the first differential amplifier and an output providing the data signal. The current steering circuit can be disabled which removes the need for the third amplifier as the data signal path is through second amplifier.

An optical device having an amplifier and a controller is described. The amplifier is configured to amplify an optical signal in at least one of the C-Band or the L-Band. The controller includes a processor and a non-transitory computer readable medium. The non-transitory computer readable medium storing computer executable code that when executed by the processor causes the processor to: select a target tilt and gain setting from a plurality of target tilt and gain settings stored in the non-transitory computer readable medium based on the type of fault event message responsive to a fault event message affecting the C-band or the L-Band. The selected and pre-calculated target tilt and gain settings are applied to the amplifier.

In order to improve reception sensitivity of a response signal at a terminal station, an optical transmission device includes a reception unit that receives a control signal including a predetermined instruction and a main signal, via an optical transmission path connected to the terminal station, a control unit that performs the predetermined instruction of the received control signal, an extraction unit that extracts light in a band of the control signal, a response signal generation unit that modulates the extracted light in the band of the control signal, and outputs a response signal, and a multiplexing unit that multiplexes and outputs the response signal and the main signal. The control unit controls modulation by the response signal generation unit according to the control signal.

An optical receiver module which receives a first optical signal including a continuous signal or a burst signal includes: a variable optical attenuator which adjusts the first optical signal to output a second optical signal; a semiconductor optical amplifier which amplifies the second optical signal to output a third optical signal; and a controller which controls an output of at least one of the variable optical attenuator and the semiconductor optical amplifier so as to cause the semiconductor optical amplifier to operate in a region in which gain saturation of the semiconductor optical amplifier does not occur, on the basis of at least one of: a power obtained by suppressing an outside portion of the wavelength band of the first optical signal in the third optical signal; and a power obtained by extracting the outside portion of the wavelength band of the first optical signal in the third optical signal.

A bidirectional optical repeater having two unidirectional optical amplifiers and a supervisory optical circuit connected to optically couple the optical ports thereof. In an example embodiment, the supervisory optical circuit provides one or more pathways therethrough for supervisory optical signals, each of these pathways having located therein a respective narrow band-pass optical filter. The supervisory optical circuit further provides one or more pathways therethrough configured to bypass the corresponding narrow band-pass optical filters in a manner that enables backscattered light of any wavelength to cross into the optical path that has therein the unidirectional optical amplifier directionally aligned with the propagation direction of the backscattered light.

An optical device having an amplifier and a controller is described. The amplifier is configured to amplify an optical signal in at least one of the C-Band or the L-Band. The controller includes a processor and a non-transitory computer readable medium. The non-transitory computer readable medium storing computer executable code that when executed by the processor causes the processor to: select a target tilt and gain setting from a plurality of target tilt and gain settings stored in the non-transitory computer readable medium based on the type of fault event message responsive to a fault event message affecting the C-band or the L-Band. The selected and pre-calculated target tilt and gain settings are applied to the amplifier.