An optical relay device is provided which is capable of outputting control signal light without equipping a light source for the control signal light and capable of flexibly managing and changing a wavelength of the control signal light in accordance with a state of a network. The optical relay device includes an optical receiving unit that receives a wavelength multiplexed optical signal, a control unit that specifies a first wavelength and outputting notification information, and a processing unit that selects an optical signal having the first wavelength from the received wavelength multiplexed optical signal, applying intensity-modulation in accordance with the notification information to the selected optical signal, adding the intensity-modulated optical signal back to the wavelength multiplexed optical signal, and outputting the wavelength multiplexed optical signal.

Aspects of the disclosure provide systems and methods which avoid the negative effects of Spectral Hole Burning when spectral changes are made for an optical communication system (OCS). Embodiments of the disclosure are directed to methods and systems which preform spectral holes for the range of wavelength channels expected to be used in the OCS. Embodiments include a configurable idle tone source for providing power to each of a set of idle tone wavelengths distributed across the spectral band used in the optical communication system. The configurable idle tone source is communicatively coupled to an output fiber of an optical network element and controlled such that optical power is present in the output optical fiber at each one of the set of idle tone wavelengths.

Example embodiments of the present invention relate to an optical signal processor comprising of at least one wavelength processing device, a plurality of optical amplifying devices, and a least one field programmable photonic device.

An optical transmission device that transmits an optical signal in a specified wavelength band includes: a receiver, a monitor light unit, a wavelength selective switch and a memory. The receiver receives the optical signal. The monitor light unit outputs monitor light of a wavelength allocated outside of the specified wavelength band. The wavelength selective switch outputs the optical signal via a first port and outputs the monitor light via a second port. The memory stores information that indicates an optical power loss of a route through which the monitor light is transmitted.

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.

There is proved an optical transmission system including: a transmitter configured to transmit an optical signal modulated with a discrete multi-tone (DMT) drive signal; a filter capable of changing a wavelength of the optical signal input from the transmitter; a monitor configured to monitor a power of the optical signal passed through the filter; and at least one processor configured to: set a center wavelength of the filter, shift the center wavelength, detect a change in the power monitored by the monitor, identify a carrier component of the optical signal based on the change in the power, and control a relative relationship between a transmission characteristic of the filter and a wavelength of the carrier component so that the carrier component is included in the optical signal and one of an upper sideband and a lower sideband of the optical signal is at least partially removed by the filter.

A method of loading a fiber optic transport system includes adding one or more control channels to an optical fiber having one or more channels, wherein each of the control channels comprises a pair of signals that are cross-polarized and each of the pair of signals is at a different frequency from one another; measuring optical power on the optical fiber; and adjusting optical power of the one or more control channels based on the measured optical power.

Methods and systems for amplifying optical signals include generating idler signals for input signals using an optical pump at a first Bragg reflection waveguide (BRW) having second order optical nonlinearity. Phase and amplitude regulation is performed using the output from the first BRW. Optical power monitoring of the input signals may be used for power equalization. The phase-sensitive amplified signal is generated at a second BRW using the optical pump. Optical power monitoring of the input signals may be used for power equalization.

An optical communication amplification system may include a number of amplification stages for an optical signal that includes a first optical wavelength band signal portion and a second optical wavelength band signal portion. Each amplification stage may separate the first optical wavelength band signal portion from the second optical wavelength band signal portion. The separated first optical wavelength band signal portion is amplified using one or more first optical wavelength band amplifiers and the separated second optical wavelength band signal portion are amplified using one or more second optical wavelength band amplifiers. The amplified first optical wavelength band signal portion is filtered and a reflected portion of the first optical wavelength band signal portion may be used to provide energy to the one or more second optical wavelength band amplifiers to increase the power or gain of the separated second optical wavelength band signal portion.

Proposed is a method of equalizing an optical signal that has an overall bandwidth formed on a number of adjacent spectral slots, wherein the signal comprises a set of non-overlapping subcarrier signals. A distribution of the subcarrier signals onto the slots is such, that at least one slot is occupied by more than one subcarrier signal. The signal is received and amplified. Respective power levels are measured for the subcarrier signals. Distribution data is provided, which indicates the distribution of the subcarrier signals onto the spectral slots. Power level data is provided, which indicates for the spectral slots respective desired power levels. For the spectral slots respective attenuation values are derived, using the measured power levels, the distribution data and the power level data. Finally, the optical transmission signal is attenuated within the spectral slots individually, using the derived attenuation values.