The invention relates to a device and a method performed by the device of monitoring an optical fibre link. The method provided for monitoring an optical fibre link comprises generating a monitoring signal used for monitoring the optical fibre link, combining the generated monitoring signal with a data signal to be transmitted over the optical fibre link, detecting backscattering of the monitoring signal from the optical fibre link, comparing the detected backscattered monitoring signal with an estimated monitoring signal backscattered along the optical fibre link, and determining, based on the comparison, at least one location along the optical fibre link where the monitoring signal is backscattered, and signal loss caused by the backscattering.

A visible light communication (VLC) device is provided for use in a VLC system. The VLC device detect a trigger condition indicating a failure of a VLC link associated with first allocated resources used to communicate with a second VLC device. In response to the detection, the VLC device terminates on the first allocated resources transmission of data to the second VLC device and transmits a fast link recovery (FLR) signal using the first allocated resources. The VLC device receives a fast link recovery response (FLR RSP) signal indicating the second VLC device received the FLR signal and, in response, the VLC device resumes transmission of data to the second VLC device.

A system for communicating supervisory information between amplifier nodes in an optical communication network utilizes modulation of an included pump source to superimpose the supervisory information on data signals (typically customer data signals) propagating between the amplifier nodes transmitted customer signals. The modulated pump appears as a modulated envelope on the amplified data signal exiting the amplifier node, and may be recovered by suitable demodulation components located at the second node (i.e., the destined receiver of the supervisory information). The supervisory information may include monitoring messages, provisioning data, protocol updates, etc., and is utilized as an input to an included modulator, which then forms a drive signal for the pump controller.

A Raman pumping arrangement for amplifying a data optical signal (40) has a Raman pump (12) for generating a Raman pump signal (44;45), an optical supervisory channel receiver (14) for receiving an optical supervisory channel signal (42) an amplification fiber (15) arranged such that the data optical signal (40), the optical supervisory channel signal (42), and the Raman pump signal (44;45) are transmitted therethrough; and a control unit (13) configured for controlling the operation of the Raman pump (12); wherein the control unit (13) is configured for setting the Raman pump (12) in an operation mode or a start-up mode; wherein in the operation mode, the Raman pump (12) provides an operation pumping power (120), and wherein in the start-up mode, the Raman pump (12) provides a start-up pumping power (122).

An optical transmission apparatus includes a receiver configured to receive a wavelength division multiplexing optical signal including a first optical signal modulated based on a first modulation system and a second optical signal modulated based on a second modulation system with a higher multi-level degree than the first modulation system; a wavelength selective switch configured to attenuate power of the first optical signal to a first level and attenuate power of the second optical signal to a second level lower than the first level; an optical amplifier configured to amplify the wavelength division multiplexing optical signal including the first optical signal and the second optical signal output from the wavelength selective switch; and a transmitter configured to transmit the wavelength division multiplexing optical signal amplified by the optical amplifier.

An amplifier receives an optical signal including a number of labeled channels via a fiber. The amplifier determines a count of the labeled channels and a spectral distribution of the labeled channels. The amplifier adjusts a parameter of the amplifier based on the count of the labeled channels and the spectral distribution of the labeled channels. The amplifier amplifies the optical signal at an adjusted output gain resulting from adjusting the parameter of the amplifier.

A system for communicating supervisory information between amplifier nodes in an optical communication network utilizes modulation of an included pump source to superimpose the supervisory information on data signals (typically customer data signals) propagating between the amplifier nodes transmitted customer signals. The modulated pump appears as a modulated envelope on the amplified data signal exiting the amplifier node, and may be recovered by suitable demodulation components located at the second node (i.e., the destined receiver of the supervisory information). The supervisory information may include monitoring messages, provisioning data, protocol updates, etc., and is utilized as an input to an included modulator, which then forms a drive signal for the pump controller.

An optical transmission apparatus includes a receiver configured to receive a wavelength division multiplexing optical signal including a first optical signal modulated based on a first modulation system and a second optical signal modulated based on a second modulation system with a higher multi-level degree than the first modulation system; a wavelength selective switch configured to attenuate power of the first optical signal to a first level and attenuate power of the second optical signal to a second level lower than the first level; an optical amplifier configured to amplify the wavelength division multiplexing optical signal including the first optical signal and the second optical signal output from the wavelength selective switch; and a transmitter configured to transmit the wavelength division multiplexing optical signal amplified by the optical amplifier.

An optical communication link that includes two nodes interconnected by an optical channel that comprises optical fiber(s), and that is used to communicate an optical signal comprising multiple optical signal wavelengths. The first node provides an optical signal onto the optical channel towards the second node, or receives an optical signal from the optical channel from the second node. A Raman pump provides Raman pump power into the optical fiber of the optical channel to thereby perform Raman amplification of the optical signal in the optical fiber. The second node determines a quality measurement of at least of optical wavelength signals transmitted by the first node to the second node. The second node also transmits information from the quality measurement back to the first node. A controller at the first node controls at least one parameter of the Raman pump in response to this transmitted information.

An amplifier receives an optical signal including a number of labeled channels via a fiber. The amplifier determines a count of the labeled channels and a spectral distribution of the labeled channels. The amplifier adjusts a parameter of the amplifier based on the count of the labeled channels and the spectral distribution of the labeled channels. The amplifier amplifies the optical signal at an adjusted output gain resulting from adjusting the parameter of the amplifier.