A power over fiber system includes a power sourcing equipment, a powered device, optical fiber cables, optical switches, a detector and a control device. The power sourcing equipment includes a semiconductor laser that oscillates with electric power, thereby outputting feed light. The powered device includes a photoelectric conversion element that converts the feed light into electric power. The optical fiber cables transmit the feed light. The optical switches selectively connect the optical fiber cables. The optical fiber cables and the optical switches can form at least two transmission routes of the feed light. The detector detects a poor transmission point on a transmission route among the transmission routes of the feed light. The control device controls the optical switches so as to form another transmission route among the transmission routes of the feed light in accordance with the poor transmission point, the transmission route bypassing the poor transmission point.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.

Provided are a submarine device, a submarine device monitoring method, and an optical communication system with which, even if a failure occurs, the failure occurrence location can be identified, and information necessary for recovery can be collected. This submarine device is provided with: a processing means for processing an input optical signal and outputting the processed optical signal; a first branching means for causing the optical signal input into the processing means to branch, and for outputting first branched light; a second branching means for causing the optical signal output from the processing means to branch, and for outputting second branched light; a selecting means for selecting and outputting the first branched light and the second branched light; and a monitoring means for monitoring the branched light output from the selecting means.

An optical transmission system includes: first and second optical transmitting units for respectively transmitting first and second optical signals that are obtained, respectively, as a result of first and second frequency-multiplexed multi-channel signals being converted by means of FM batch conversion; a carrier monitoring function unit for monitoring each carrier signal included in the optical signals; an output adjustment unit for adjusting signal intensities of the optical signals and outputting the optical signals; a multiplexer for outputting a multiplexed signal of the optical signals; an amplifier for amplifying the multiplexed signal; and first and second optical receiving units for receiving the respective optical signals included in the amplified multiplexed signal. The output adjustment unit adjusts the respective signal intensities of the optical signals such that the signal intensity at each optical receiving unit is larger than or equal to a predetermined value. The carrier monitoring function unit updates the predetermined values based on a minimum optical sensitivity that is calculated based on the amount of frequency deviation of each carrier signal included in the optical signals.

A power over fiber system includes a power sourcing equipment, a powered device, optical fiber cables, optical switches, a detector and a control device. The power sourcing equipment includes a semiconductor laser that oscillates with electric power, thereby outputting feed light. The powered device includes a photoelectric conversion element that converts the feed light into electric power. The optical fiber cables transmit the feed light. The optical switches selectively connect the optical fiber cables. The optical fiber cables and the optical switches can form at least two transmission routes of the feed light. The detector detects a poor transmission point on a transmission route among the transmission routes of the feed light. The control device controls the optical switches so as to form another transmission route among the transmission routes of the feed light in accordance with the poor transmission point, the transmission route bypassing the poor transmission point.

A regen node is described. The regen node includes a coherent receiver, a control module and a coherent transmitter. The coherent receiver has circuitry to convert a first optical signal received from an upstream node in an optical layer of an optical network to a first digital data stream in a digital layer having a first FEC frame and a data traffic. The control module extracts a first fault signal from the first FEC frame; generates a second fault signal based at least in part on the first fault signal; and encodes the second fault signal within a second FEC frame with the data traffic into a second digital data stream on the digital layer. The coherent transmitter has circuitry to convert the second digital data stream into a second optical signal on the optical layer and to transmit the second optical signal to a downstream node.

A regen node is described. The regen node includes a coherent receiver, a control module and a coherent transmitter. The coherent receiver has circuitry to convert a first optical signal received from an upstream node in an optical layer of an optical network to a first digital data stream in a digital layer having a first FEC frame and a data traffic. The control module extracts a first fault signal from the first FEC frame; generates a second fault signal based at least in part on the first fault signal; and encodes the second fault signal within a second FEC frame with the data traffic into a second digital data stream on the digital layer. The coherent transmitter has circuitry to convert the second digital data stream into a second optical signal on the optical layer and to transmit the second optical signal to a downstream node.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.

An optical signal monitor, including: a storage that holds a threshold value set for each of determination areas having a bandwidth set in accordance with an average grid of dummy light; a measurement section that sequentially measures an optical intensity of an inputted wavelength-multiplexed optical signal with respect to each of measurement areas obtained by dividing the determination area into areas with a bandwidth sufficiently smaller than a grid width of a monitoring-target optical signal composing the wavelength-multiplexed optical signal, and output measured values; and a section that determines that dummy light corresponding to the determination area needs introducing if each of measured values in the determination area is smaller than a threshold value, and, determines that dummy light corresponding to the determination area does not need introducing if at least one of the measured values in the determination area is equal to or larger than the threshold value.