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 method, implemented in an optical line system, includes monitoring traffic channels of a plurality of traffic channels; determining one or more traffic channels of the plurality of traffic channels are problematic with respect to other traffic channels of the plurality of traffic channels; and squelching the one or more traffic channels and replacing the squelched one or more traffic channels with channel holders. The method can further include continuing the monitoring of the squelched one or more traffic channels; determining the squelched one or more traffic channels are no longer problematic; and re-adding the squelched one or more traffic channels by replacing the channel holders therewith.

Assemblies and methods are described that provide for monitoring output from light emitting sources, such as vertical-cavity surface-emitting lasers. In particular, the assembly includes an array of light emitting sources, an array of lenses, an array of photodiodes, and a controller. The light is emitted by the array of light emitting sources, which in turn is configured to emit light towards the array of lenses. A photo-induced current is generated at the array of photodiodes, which is arranged to receive light reflected off of the array of lenses. The assembly determines a change in operational status of one or more of the light emitting sources based on the photo-induced currents.

Techniques for providing high-resolution, standard-format output for line monitoring equipment (LME) of a wavelength division multiplexed (WDM) communication system is disclosed. LME may transmit a plurality of LME test signals via an optical path of the WDM system and perform gain measurements on reflections associated with the same at predetermined intervals. Gain measurements for each of the plurality of LME test signals may be normalized and filtered to derive LME peak data. The WDM communication system may perform full scans with data points totaling millions/billions (e.g., depending on system length, fiber type, and number of transmitted LME test signals or test pulses) and normalize the same into a relatively small number of resulting data points within the LME peak data. The WDM system may then output an LME results file in a standard format which is compatible with commercial viewers and optical time domain reflectometer (OTDR) equipment.

An optical time-domain reflectometer, OTDR, apparatus is configured to measure a backscattered trace of a fiber link under test (FLUT). The OTDR apparatus includes at least one photo diode adapted to detect an optical signal reflected from points along the fiber link under test in response to an optical test signal generated by a laser of the OTDR apparatus and supplied to the fiber link under test. The reflected optical test signal is attenuated or amplified automatically such that the power of the optical signal received by the photodiode is limited to a predetermined power range.

An optical transmission apparatus includes a wavelength selection switch configured to: receive signal light, and attenuate power of the received signal light; an optical amplifier coupled to the wavelength selection switch and configured to optically amplify the attenuated signal light; and a processor configured to control the wavelength selection switch to attenuate power of signal light which passes a channel which is newly set by an attenuation amount based on information on light levels of spontaneous emission light generated by the optical amplifier.

A method for calculating configuration of an optical transmission network includes: acquiring an initial value of an input power of an optical cable; based on the initial value, obtaining an output power of each channel at an end of a section of the optical cable according to a loss of the optical cable; taking the output power of each channel at the end of the section as a boundary condition to calculate the input power of each channel at the section based on an amount of optical power transferred from a high-frequency channel to a low-frequency channel due to an SRS effect; and calculating a first parameter value of an optical amplifier of the section using the input power of each channel at the section and the output power of each channel at the end of a preceding section of the section.

A system includes an encoding circuit, a line quality monitor circuit, and a controller circuit. The encoding circuit generates a first data signal indicating encoded data using a first forward error correction code. The line quality monitor circuit generates an indication of a line quality of a second data signal using an eye monitor circuit that monitors the second data signal. The controller circuit causes the encoding circuit to generate encoded data in the first data signal using a second forward error correction code in response to a change in the indication of the line quality of the second data signal.

An optical amplification estimation method includes by an excitation light output unit connected to a first end of a first optical transmission line, making excitation light incident on the first optical transmission line, by a monitoring unit connected to the same side as the first end of the first optical transmission line, making monitoring light incident on the first optical transmission line, the monitoring light having a wavelength different from a wavelength of the excitation light, by the monitoring unit, measuring intensity of light incident on the monitoring unit when the excitation light is incident, and intensity of light incident on the monitoring unit when the excitation light is not incident, and by an amplification estimation unit, estimating a gain of an optical signal in the first optical transmission line based on the light intensity measured in the measuring. The first optical transmission line shares a partial optical transmission line with a second optical transmission line used for an optical network unit and an optical line terminal to transmit and receive an optical signal to and from each other.

Techniques for providing high-resolution, standard-format output for line monitoring equipment (LME) of a wavelength division multiplexed (WDM) communication system is disclosed. LME may transmit a plurality of LME test signals via an optical path of the WDM system and perform gain measurements on reflections associated with the same at predetermined intervals. Gain measurements for each of the plurality of LME test signals may be normalized and filtered to derive LME peak data. The WDM communication system may perform full scans with data points totaling millions/billions (e.g., depending on system length, fiber type, and number of transmitted LME test signals or test pulses) and normalize the same into a relatively small number of resulting data points within the LME peak data. The WDM system may then output an LME results file in a standard format which is compatible with commercial viewers and optical time domain reflectometer (OTDR) equipment.