Abstract: A transmission characteristics monitoring device monitors transmission characteristics of an optical transmission path between nodes. The device detects an average power of the frequency modulated optical signal and a slope of the transmission characteristics; generates a slope function that represents a slope of the transmission characteristics between first and second frequencies; generates a corrected power value by adding an integral of the slope function to a first power measurement value detected at the first frequency; calculates the transmission characteristics at the second frequency based on a second power measurement value detected at the second frequency when the difference between the second power measurement value and the corrected power value is smaller than a specified threshold; and calculates the transmission characteristics at the second frequency based on the corrected power value when the difference is greater than the specified threshold.

Abstract: An optical receiver includes: a tunable filter configured to partially transmit a wavelength-multiplexed optical-signal including a first optical-signal having a first wavelength, a second optical-signal having a second wavelength, and a third optical-signal having a third wavelength, with a frequency-modulated signal superimposed on each of the first to third optical-signals; a photo detector configured to detect an optical-power of the wavelength-multiplexed optical-signal transmitted through the tunable filter; and a superimposed signal detector configured to detect the frequency-modulated signal superimposed on the first optical-signal, based on an amplitude-modulated signal according to a variation in the optical-power on a first filter setting where both of the first optical-signal and the second optical-signal transmit through the tunable filter, and an amplitude-modulated signal according to a variation in the optical-power on a second filter setting where both of the first optical-signal and the thir

Abstract: There is provided an apparatus configured to estimate optical transmission performance in a transmission path of an optical signal, the apparatus including a memory, and a processor coupled to the memory and the processor configured to acquire a first index related to a first transmission performance of an optical signal transmitted through a span group between a first node and an n-th node and a second index related to a second transmission performance of an optical signal transmitted through a span or a span group between the first node and an m-th node, wherein n is an integer of 3 or more, and m is the integer satisfying m<n, and estimate a third index related to a third transmission performance of an optical signal to be transmitted through a span between the m-th node and the n-th node, based on the first index and the second index.

Abstract: A network control apparatus includes a processor. The processor calculates a first OSNR corresponding to an allowable limit BER from an OSNR yield strength curve of a transmission end in a node of a transmission end. The processor acquires a reception BER of a second node of a reception end, and calculates a second OSNR corresponding to the reception BER from the OSNR yield strength curve of the transmission end. The processor calculates a first noise intensity corresponding to the allowable limit BER from the first OSNR. The processor calculates a second noise intensity corresponding to the reception BER from the second OSNR. The processor calculates a noise intensity margin, based on the first noise intensity and the second noise intensity.

Abstract: A transmission system includes: an acquisition section configured to acquire a free band between a target channel including a plurality of wavelength signals contiguous to one another and a channel adjacent to the target channel; and an adjustment section configured to adjust signal power of at least one of the plurality of wavelength signals in the target channel, based on a power adjustment amount for the wavelength signal, the power adjustment amount being provided for the free band acquired by the acquisition section.

Abstract: A transmission characteristics monitoring device monitors transmission characteristics of an optical transmission path between nodes. The device detects an average power of the frequency modulated optical signal and a slope of the transmission characteristics; generates a slope function that represents a slope of the transmission characteristics between first and second frequencies; generates a corrected power value by adding an integral of the slope function to a first power measurement value detected at the first frequency; calculates the transmission characteristics at the second frequency based on a second power measurement value detected at the second frequency when the difference between the second power measurement value and the corrected power value is smaller than a specified threshold; and calculates the transmission characteristics at the second frequency based on the corrected power value when the difference is greater than the specified threshold.

Abstract: An optical signal-to-noise ratio (OSNR) measuring device includes a processor, wherein the processor executes a process. The process includes: converting an optical signal to an electrical signal; first acquiring a signal intensity from the electrical signal; second acquiring a noise intensity of a predetermined frequency band from the electrical signal; performing a digital conversion on the noise intensity; and computing an OSNR of the optical signal based on the signal intensity and the converted noise intensity. The predetermined frequency band is a frequency band including a folding noise that occurs when the digital conversion is performed.

Abstract: An optical transmission apparatus includes a variable attenuator configured to adjust output intensity of each wavelength signal included in a multiplexed optical signal having been input; a monitor configured to measure an output spectrum of the variable attenuator; a calculation unit configured to calculate an amount of spectral narrowing and an amount of spectral surplus, based on a measured value by the monitor, and a target value set in advance; and a control unit configured to control an amount of attenuation of the variable attenuator, based on the amount of spectral narrowing and the amount of spectral surplus.

Abstract: A communication device that receives received signal light from another communication device, the communication device includes: a receiver configured to receive signal light output from an optical filter that outputs signal light of a given wavelength included the received signal light; and a transmitter configured to transmit, to the another communication device, a control signal for controlling a wavelength of laser light for use in generation of the signal light of the given wavelength, wherein the receiver is configured to detect power of the signal light output from the optical filter; and the transmitter is configured to set, when the signal light is not successfully received in the receiver, the control signal so as to cause the another communication device to control the wavelength of the laser light, based on the power.

Abstract: An optical transmission apparatus includes: an optical amplifier configured to amplify an optical signal; an optical power adjustment unit configured to adjust power of the optical signal output from the optical amplifier; and a controller configured to control an adjustment amount of the optical power in the optical power adjustment unit, in accordance with optical power control information obtained based on output optical power information per wavelength indicating output optical power that the optical amplifier is capable of outputting depending on a number of wavelengths included in the optical signal, and requisite signal quality information in a reception node which is to receive the optical signal output from the optical amplifier.

Abstract: An optical transmission device includes: a plurality of optical transceivers; a wavelength selective switch; and a controller configured to control the plurality of optical transceivers and the wavelength selective switch. Each of the optical transceivers includes a wavelength tunable light source. The controller controls a wavelength of a wavelength tunable light source of a selected optical transceiver according to a wavelength of an optical signal received by the destination remote device. The controller controls the wavelength selective switch so as to generate the WDM optical signal from a plurality of optical signals generated by the plurality of optical transceivers, and to guide the plurality of optical signals received from the plurality of remote devices to the plurality of optical transceivers according to wavelengths of the received plurality of optical signals.

Abstract: An optical transmission apparatus includes a first optical transmission line through which the signal of the first channel pass, the signal having a signal quality at a first strength and; an optical receiver configured to receive, from a network control apparatus, information about a second strength based on a signal quality of a signal of a second channel passing through a second optical transmission line of which at least a portion is a same as that of the signal of the first channel; and an optical transmitter configured to transmit the signal of the first channel at the second strength.

Abstract: There is provided a measurement apparatus of measuring signal light quality. The measurement apparatus may include: a tunable wavelength filter configured to be input signal lights having different power levels; a measure configured to measure an optical power level of light passing through the tunable wavelength filter; and a controller configured to calculate a non-linear noise component and a spontaneous emission component of a signal light based on the measured optical power levels, the optical power levels being measured at different transmission frequencies for each of the signal lights having the different power levels in response to a control of the transmission frequency of the tunable wavelength filter.

Abstract: A transmitter generates a frequency-modulated CW light so as to transmit it to a path. A receiver receives the CW light that has passed through passband filters included in the path. The receiver includes a processor. The processor measures an optical power of the received CW light every time a center frequency of the CW light is changed and transmitted by the transmitter. The processor calculates transmission characteristics of the CW light that has passed through the passband filters, on the basis of an average value of the optical power that corresponds to a center frequency of the CW light and on the basis of an amplitude component that indicates an amount of change in the optical power, the average value and the amplitude component being obtained as a result of the measurement.

Abstract: An optical transmission device includes a transmission unit, a filter unit, a detection unit, and a control unit. The transmission unit superimposes identical superimposition signals of a frequency modulation method on a plurality of optical signals that have identical destinations and that have adjacent wavelengths, and transmits resultant signals as one communication signal. The filter unit filters part of two optical signals having adjacent wavelengths from among the plurality of optical signals included in the communication signal. The detection unit generates an electric signal of a detection level representing an optical intensity of the two optical signals that were filtered by the filter unit. The control unit controls timings of superimposing the superimposition signals on the two optical signals respectively by controlling the transmission unit so that variation in the detection level becomes smaller.

Abstract: A network controller includes: a first acquisition unit configured to acquire, based on a signal quality amount of each of wavelength paths set in a network of an optical wavelength-multiplexed transmission system, a signal quality amount of each of spans in each of the wavelength paths; an arithmetic unit configured to calculate a signal quality amount of each of spans in a wavelength path of an estimation target, based on the signal quality amount acquired by the first acquisition unit; and an estimation unit configured to estimate a signal quality amount of the wavelength path of the estimation target, based on the signal quality amount calculated by the arithmetic unit.

Abstract: A signal detection circuit includes: a first optical filter configured to filter an optical signal carrying a frequency modulated signal with a first transmission band; a second optical filter configured to filter the optical signal with a second transmission band; a first photo detector configured to convert the output light of the first optical filter into a first electrical signal; a second photo detector configured to convert the output light of the second optical filter into a second electrical signal; a difference circuit configured to output a signal representing a difference between the first electrical signal and the second electrical signal; and a detector configured to detect the frequency modulated signal based on the output signal of the difference circuit.

Abstract: An optical receiver includes: a tunable filter configured to partially transmit a wavelength-multiplexed optical-signal including a first optical-signal having a first wavelength, a second optical-signal having a second wavelength, and a third optical-signal having a third wavelength, with a frequency-modulated signal superimposed on each of the first to third optical-signals; a photo detector configured to detect an optical-power of the wavelength-multiplexed optical-signal transmitted through the tunable filter; and a superimposed signal detector configured to detect the frequency-modulated signal superimposed on the first optical-signal, based on an amplitude-modulated signal according to a variation in the optical-power on a first filter setting where both of the first optical-signal and the second optical-signal transmit through the tunable filter, and an amplitude-modulated signal according to a variation in the optical-power on a second filter setting where both of the first optical-signal and the thir

Abstract: An optical transmitting device includes: an optical modulator configured to modulate light output from a light source with a drive signal generated by controlling a frequency of a first signal based on a second signal; and an amplitude controller configured to control amplitude of the first signal based on a control signal, wherein signal light modulated by the optical modulator is transmitted to an optical receiving device.

Abstract: An optical signal-to-noise ratio monitor includes: a measuring unit that measures an optical signal-to-noise ratio of a polarization multiplexed optical signal, a polarization state of the polarization multiplexed optical signal changing with respect to time; a selector that selects, from a plurality of optical signal-to-noise ratios measured by the measuring unit at a plurality of measurement points within a designated measurement period, an optical signal-to-noise ratio that is higher than an average of the plurality of optical signal-to-noise ratios; and an output unit that outputs the optical signal-to-noise ratio selected by the selector.