Abstract: An optical amplifier according to the present disclosure includes a first excitation light coupler, a first optical amplification medium, a first optical switch configured to output the optical communication signal output from the first optical amplification medium to either a first branch path HGP or a second branch path, and a second optical switch configured to transmit the optical communication signal transmitted through the branch path to downstream, and the first branch HGP path includes a second optical amplification medium, a second excitation light coupler configured to synthesize the optical communication signal and the excitation light directed towards the second optical amplification medium, and a first gain equalizer, and the second branch path includes a third excitation coupler configured to synthesize the optical communication signal and the excitation light directed towards the first optical switch, and a second gain equalizer.

Abstract: The present disclosure relates to an NE (90) in a WDM transmission system. The NE (90) according to the present disclosure includes a WSS (901) which allows, in accordance with configurations allocated to a plurality of respective slots, optical signals of the plurality of respective slots to pass, and a WSS control unit (902) which allocates a configuration to each of the plurality of slots. The WSS control unit (902) additionally allocates, if an adjacent slot adjacent to a desired one of the plurality of slots is unused, a configuration for allowing an optical signal to pass through a path the same as that of the desired slot to the adjacent slot.

Abstract: A node (10) includes multiplexing unit (11) that multiplexes a plurality of subcarrier signals for performing optical wavelength multiplexing communication into a wavelength group signal; output unit (12) that outputs the multiplexed wavelength group signal to an optical transmission line; pre-multiplexing level correction unit (13) that corrects a level deviation between the subcarrier signals before the multiplexing based on an optical level of the wavelength group signal in the output unit (12); and post-multiplexing level correction unit (14) that corrects a level deviation of the wavelength group signal after the multiplexing including the corrected subcarrier signals based on the optical level of the wavelength group signal in the output unit (12).

Abstract: A node (10) includes multiplexing unit (11) that multiplexes a plurality of subcarrier signals for performing optical wavelength multiplexing communication into a wavelength group signal; output unit (12) that outputs the multiplexed wavelength group signal to an optical transmission line; pre-multiplexing level correction unit (13) that corrects a level deviation between the subcarrier signals before the multiplexing based on an optical level of the wavelength group signal in the output unit (12); and post-multiplexing level correction unit (14) that corrects a level deviation of the wavelength group signal after the multiplexing including the corrected subcarrier signals based on the optical level of the wavelength group signal in the output unit (12).

Abstract: An optical detection unit detects a return light and outputs a detection signal. An optical multiplexer/demultiplexer outputs the monitoring light to the optical transmission line, and outputs the return light to the optical detection unit. A processing unit detects a first timing at which the detection signal becomes less than a first threshold value, detects a second timing at which the detection signal becomes less than a second threshold value, and calculates a first change rate of the detection signal in a period between the first and second timings. The processing unit changes the first and second threshold values to calculate the first change rate for a plurality of periods, and, when a second change rate between the first change rates in two adjacent periods is greater than a threshold value, either of the first and second timings in one period is detected as the breakage position.

Abstract: An object is to automatically detect a failure of an optical transmission line. A light source outputs a monitoring light. An optical detection unit detects a return light from an optical transmission line and outputs a detection signal indicating an intensity of the return light. An optical multiplexer/demultiplexer outputs the monitoring light input from the light source to the optical transmission line, and outputs the return light input from the optical transmission line to the optical detection unit. A comparator compares the detection signal with a threshold voltage and outputs a comparison signal indicating the comparison result. A processing unit detects a first timing at which the comparison signal changes, and detects a failure of the optical transmission line when the first timing is earlier than a reference timing.

Abstract: An object is to automatically detect a failure of an optical transmission line. A light source outputs a monitoring light. An optical detection unit detects a return light from an optical transmission line and outputs a detection signal indicating an intensity of the return light. An optical multiplexer/demultiplexer outputs the monitoring light input from the light source to the optical transmission line, and outputs the return light input from the optical transmission line to the optical detection unit. A comparator compares the detection signal with a threshold voltage and outputs a comparison signal indicating the comparison result. A processing unit detects a first timing at which the comparison signal changes, and detects a failure of the optical transmission line when the first timing is earlier than a reference timing.

Abstract: An optical detection unit detects a return light and outputs a detection signal. An optical multiplexer/demultiplexer outputs the monitoring light to the optical transmission line, and outputs the return light to the optical detection unit. A processing unit detects a first timing at which the detection signal becomes less than a first threshold value, detects a second timing at which the detection signal becomes less than a second threshold value, and calculates a first change rate of the detection signal in a period between the first and second timings. The processing unit changes the first and second threshold values to calculate the first change rate for a plurality of periods, and, when a second change rate between the first change rates in two adjacent periods is greater than a threshold value, either of the first and second timings in one period is detected as the breakage position.

Abstract: [Problem] To provide an optical transmission device that, while suppressing band narrowing due to optical filters, achieves flexibility of optical communication such as wavelength reutilization and that supports a flexible grid. [Solution] An optical transmission device according to the present invention is provided with a cyclic AWG that filters respective optical signals inputted to each input port. The respective optical signals are constituted so that a plurality of wavelength-multiplexed signals can be allocated within one channel band, the respective optical signals are filtered in channel units, and the pass-band width of each of the input ports of the cyclic AWG corresponds to the bandwidth of a channel.

Abstract: [Problem] To provide an optical device capable of suppressing an optical signal from being trimmed because of band narrowing due to optical filters. [Solution] An optical device according to the present invention is provided with a plurality of optical filters each of which filters an optical signal in a predetermined band out of a plurality of optical signals with wavelengths different from one another. The plurality of optical filters are configured in such a way that portions of the pass bands (13_1, 13_2, 13_3) of respective optical filters that respectively pass optical signals (15_1, 15_2, 15_3) with wavelengths adjacent to each other overlap each other.

Abstract: A node (10) includes multiplexing unit (11) that multiplexes a plurality of subcarrier signals for performing optical wavelength multiplexing communication into a wavelength group signal; output unit (12) that outputs the multiplexed wavelength group signal to an optical transmission line; pre-multiplexing level correction unit (13) that corrects a level deviation between the subcarrier signals before the multiplexing based on an optical level of the wavelength group signal in the output unit (12); and post-multiplexing level correction unit (14) that corrects a level deviation of the wavelength group signal after the multiplexing including the corrected subcarrier signals based on the optical level of the wavelength group signal in the output unit (12).

Abstract: [Problem] To provide an optical device capable of suppressing an optical signal from being trimmed because of band narrowing due to optical filters. [Solution] An optical device according to the present invention is provided with a plurality of optical filters each of which filters an optical signal in a predetermined band out of a plurality of optical signals with wavelengths different from one another. The plurality of optical filters are configured in such a way that portions of the pass bands (13_1, 13_2, 13_3) of respective optical filters that respectively pass optical signals (15_1, 15_2, 15_3) with wavelengths adjacent to each other overlap each other.

Abstract: [Problem] To provide an optical transmission device that, while suppressing band narrowing due to optical filters, achieves flexibility of optical communication such as wavelength reutilization and that supports a flexible grid. [Solution] An optical transmission device according to the present invention is provided with a cyclic AWG that filters respective optical signals inputted to each input port. The respective optical signals are constituted so that a plurality of wavelength-multiplexed signals can be allocated within one channel band, the respective optical signals are filtered in channel units, and the pass-band width of each of the input ports of the cyclic AWG corresponds to the bandwidth of a channel.

Abstract: An optical channel monitor includes a demultiplexer, a plurality of paths and a processing section. The demultiplexer demultiplexes an input optical signal, which is wavelength-multiplexed, for respective multiplexed wavelengths to generate a plurality of optical signals. The plurality of paths respectively generate a plurality of digital signals indicating optical powers of the plurality of optical signals. The processing section inputs the plurality of digital signals to calculate correction values of the optical powers, which correspond to characteristics of the demultiplexer. The demultiplexer includes a filter having FMHM (Full With at Half Maximum) within a predetermined range. The predetermined range is set based on a pass center wavelength accuracy of the filter and an oscillation wavelength accuracy of a transponder which generates the input optical signal.

Abstract: A light channel monitor includes an optical separating section configured to separate a wavelength multiplexed optical signal into optical signals for channels and monitors configured to measure intensities of the optical signals for the channels. A processing section is configured to correct the measured intensities of the optical signals based on a wavelength transmission characteristic of the optical separating section to calculate the wavelength multiplexed optical signal before the separation.

Abstract: The present invention reduces the number of amplifiers and reduces the maximum output of an optical transmission device. A wavelength selection unit selects and outputs, as a drop signal, any given wavelength of optical signal from an input optical signal. An amplifier amplifies at each wavelength the drop signal output by the wavelength selection unit. In this case, the number of amplifiers is set smaller than the number of wavelengths of the input optical signal. Also, the wavelength selection unit selects a number of wavelengths of drop signals corresponding to the number of amplifiers, and outputs the drop signals to the amplifiers at each wavelength.

Abstract: The present invention reduces the number of amplifiers and reduces the maximum output of an optical transmission device. A wavelength selection unit selects and outputs, as a drop signal, any given wavelength of optical signal from an input optical signal. At each wavelength, an amplifier amplifies the drop signal output by the wavelength selection unit. In this case, the number of amplifiers is set lower than the number of wavelengths of the input optical signal. Also, the wavelength selection unit selects a number of wavelengths of drop signals corresponding to the number of amplifiers, and outputs the selected drop signals to the amplifiers at each wavelength.

Abstract: An optical channel monitor includes a demultiplexer, a plurality of paths and a processing section. The demultiplexer demultiplexes an input optical signal, which is wavelength-multiplexed, for respective multiplexed wavelengths to generate a plurality of optical signals. The plurality of paths respectively generate a plurality of digital signals indicating optical powers of the plurality of optical signals. The processing section inputs the plurality of digital signals to calculate correction values of the optical powers, which correspond to characteristics of the demultiplexer. The demultiplexer includes a filter having FMHM (Full With at Half Maximum) within a predetermined range. The predetermined range is set based on a pass center wavelength accuracy of the filter and an oscillation wavelength accuracy of a transponder which generates the input optical signal.

Abstract: A method of collecting data from an optical channel monitor for monitoring the power of a wavelength-division multiplexed light signal at each wavelength is disclosed. The total light power is analog-to-digital converted by an A/D converter. The data of the total light power which has been analog-to-digital converted is compared with a reference light power by a comparator for each conversion, and when the difference between the total light power and the reference light power exceeds a predetermined threshold, a power fluctuation flag is turned ON. After the comparison, the above process of the analog-to-digital conversion and the comparison is iterated until the optical channel monitor completes the data collection for each wavelength. Thereafter, the processor determines whether the power fluctuation flag is ON or not. When the power fluctuation flag is ON, the processor discards the currently collected data and maintains the data which were collected immediately before.

Abstract: Methods and systems for controlling power fluctuations in a network including a plurality of nodes are disclosed. A node in the network may be configured to modify power levels in accordance with either an active state or an inactive state. The node may transition to an inactive state in response to a power change that exceeds a power change threshold. The role of the node in controlling the power fluctuation in the network is reduced in the inactive state.