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.

A sampling frequency required for symbol timing recovery is made smaller than that of the related art. A receiver 1 performs visible light communication with a transmitter 8. A received signal generating unit 112 measures an intensity of an electrical signal corresponding to an optical signal received from a transmitter 8 at a predetermined time interval to generate a sequence of received signals. A parameter estimation unit 12 uses a distribution of received signals estimated from the sequence of received signals to estimate any one or more parameters of a maximum luminance value, a synchronization shift, and a steady noise level, the one or more parameters including at least the maximum luminance value.

Systems and methods are provided for re-calibrating an in-service Optical Multiplex Section (OMS) while it is operating in an optical system. A method, according to one implementation, includes a step of analyzing a state of at least one component of the in-service OMS in an optical network, whereby the at least component may include, among other things, one or more fiber spans. Based on a need to re-calibrate the at least one component of the OMS, the method also includes the step of transitioning the OMS from an in-service mode to a maintenance mode to prepare the OMS for re-calibration. At this point, a re-calibration procedure can be performed. In response to completing the re-calibration procedure, the method includes the step of transitioning the OMS from the maintenance mode back to the in-service mode.

Provided is a communication monitoring system capable of monitoring a state of a connection device that forms an optical path by using an optical passive component. A communication monitoring system (1) includes a plurality of photodetectors (9) provided in a connection device (6), a plurality of recognition units (13), a processing unit (14), a light emitting unit (15), a mixing unit (12), a separation unit (16), a collection unit (17), and a management unit (18). The photodetector (9) detects an optical signal passing through a corresponding optical path. The recognition unit (13) recognizes a state of detection by the corresponding photodetector (9). The processing unit (14) generates information regarding a communication state of the connection device (6) on the basis of the recognition by each recognition unit (13). The light emitting unit (15) converts the generated information into a monitoring signal that is an optical signal and transmits the monitoring signal. The monitoring signal is passed through an optical communication line (3) as a mixed signal by the mixing unit (12) and is separated from the mixed signal by the separation unit (16). The collection unit (18) outputs the separated monitoring signal to the management unit (18) that manages a state of a PON (2).

An optical transmission device includes: a frontend circuit, a converter, an equalizer, a recovery, spectrum detector a correction information generator, and a transmitter. The frontend circuit converts an optical signal received via an optical network into an electric signal. The converter converts an output signal of the frontend circuit into a digital signal. The equalizer equalizes the digital signal or a second digital signal that is generated based on the digital signal. The recovery recovers a symbol from an output signal of the equalizer. The spectrum detector detects a reception spectrum of the optical signal based on the digital signal or the second digital signal. The correction information generator generates, according to the reception spectrum, correction information for correcting a shape of a transmission spectrum of the optical signal. The transmitter transmits the correction information to the source device.

An optical transmission device includes: a frontend circuit, a converter, an equalizer, a recovery, spectrum detector a correction information generator, and a transmitter. The frontend circuit converts an optical signal received via an optical network into an electric signal. The converter converts an output signal of the frontend circuit into a digital signal. The equalizer equalizes the digital signal or a second digital signal that is generated based on the digital signal. The recovery recovers a symbol from an output signal of the equalizer. The spectrum detector detects a reception spectrum of the optical signal based on the digital signal or the second digital signal. The correction information generator generates, according to the reception spectrum, correction information for correcting a shape of a transmission spectrum of the optical signal. The transmitter transmits the correction information to the source device.

Systems and methods for enabling robust fault tolerance targeting runtime failures in multi-wavelength optical links. The proposed embodiment relies on built-in lane redundancy where failure can be detected and repaired during runtime and in an online fashion. Features allow out-of-band and side-band communication.

Systems and methods for enabling robust fault tolerance targeting runtime failures in multi-wavelength optical links. The proposed embodiment relies on built-in lane redundancy where failure can be detected and repaired during runtime and in an online fashion. Features allow out-of-band and side-band communication.

The communication device 111 included in the active cable comprises a controller 11, a comparator 12, a resistor 13, a voltage source 14, and a redriver 16. The comparator 12 receives the voltage value of the SBU signal line and the reference voltage value output from the voltage source 14, and compares the voltage value of the SBU signal line with the reference voltage value to detect the level of the sideband signal. The controller 11 receives the detection result of the sideband signal level from the comparator 12, and sets the redriver 16, which is an active device, to the low-power-consumption state when the sideband signal level stays at L level for a predetermined period of time or longer.