An alarm processing method and apparatus is disclosed. Specifically, a mechanism of configuring and detecting an LOF pre-alarm is provided. A detection condition of the LOF pre-alarm is that it is detected that a frame alignment failure lasts for first duration. A detection condition of the LOF alarm is that it is detected that a frame alignment failure lasts for second duration. The second duration is less than the first duration. When detecting the LOF pre-alarm, a network device inserts a first maintenance signal frame. The first maintenance signal frame supports frame alignment. In other words, a network device that receives the first maintenance signal frame may perform normal frame alignment, so that no alarm is reported, for example, the LOF alarm is not triggered.

An alarm processing method and apparatus is disclosed. Specifically, a mechanism of configuring and detecting an LOF pre-alarm is provided. A detection condition of the LOF pre-alarm is that it is detected that a frame alignment failure lasts for first duration. A detection condition of the LOF alarm is that it is detected that a frame alignment failure lasts for second duration. The second duration is less than the first duration. When detecting the LOF pre-alarm, a network device inserts a first maintenance signal frame. The first maintenance signal frame supports frame alignment. In other words, a network device that receives the first maintenance signal frame may perform normal frame alignment, so that no alarm is reported, for example, the LOF alarm is not triggered.

Configurations for a modal interference device used for wavelength locking are disclosed. The modal interference device may be an interference device that includes an input waveguide, an interference waveguide, and an output waveguide. A fundamental mode of light may be launched into the input waveguide and the interference waveguide may receive the fundamental mode and generate a higher order mode of light, where the two modes of light may be superimposed while propagating through the interference waveguide. The two modes of light may be received at an output waveguide that collapses the two modes into a single mode and generates an output signal corresponding to the interference between the two modes of light. The output signal may be used to wavelength lock a measured wavelength to a target wavelength. The multiple output waveguides may produce output signals that have dead zones that do not align with one another for any wavelength in the wavelength range of interest.

A method to determine the types of optical fibers forming a link of an optical communication network. By scanning a signal's bit error rate at a receiver end, as a function of a pre-dispersion applied to a signal at a transmitter end, local minimums in the curve indicate the presence of amplifiers, and therefore fiber span extremities. By determining the accumulated dispersion at each fiber extremity, a ratio of dispersion per span length can be obtained and the span's coefficient of chromatic dispersion be inferred, thereby identifying the type of fiber. Alternatively, a signal's signal-to-noise ratio can be scanned, instead of its bit error rate. In a typical network, the required instrumentation is pre-existing.

An optical receiver includes an optical amplifier that amplifies a received optical signal containing multiple wavelengths, a monitor circuit that monitors light intensities of the demultiplexed optical signal, a processor, and a memory having information representing a relationship between a total incident light intensity of the optical signal incident onto the optical amplifier and gains of the optical amplifier for the respective wavelengths. The processor repeats first calculation for determining the gains of the respective wavelengths from the memory, based on a drive current for driving the optical amplifier and an estimation value of the total incident light intensity of the optical signal, second calculation for calculating the incident light intensities of the respective wavelengths of the optical signal based on the gains and the monitored light intensities, and third calculation to calculate the total incident light intensity of the optical signal, until the total incident light intensity converges.

An optical transmitter device includes a modulator of the Mach-Zehnder type that modulates the optical signal from an emitter and outputs modulated signals; and a phase controller that controls the phase difference of the modulator according to a setting phase amount. The device includes a controller, a sweeper, and an estimator. The controller controls the bias current of the emitter so that the power of the modulated signals detected at the output stage of the modulator during the optical shutdown becomes the target value during the optical shutdown. After the bias current is controlled, the sweeper performs constant-period sweeping of the phase of the modulator. The estimator estimates, while sweeping the phase, the transmission characteristics of the modulator from the power of the optical signal detected at the input stage of the modulator; and, from the estimated characteristics, calculates the optimum phase amount to be set in the phase controller.

Systems and methods are provided for controlling one or more optical amplifiers of a C+L band photonic line system (30) of a telecommunications network in which C-band signals and L-band signals may be transmitted. In one implementation, a method (130) may execute a traffic managing module (23). When executed, the traffic managing module (23) may be configured to enable a processing device (12) to calculate (132) a gain correction profile based on a difference between a saved baseline transmission profile (84) and a measured transmission profile (94) of a surviving band of a photonic line system (30) when another band of the photonic line system (30) is missing or impacted. The traffic managing module (23) may further be configured to enable the processing device (12) to apply (134) the gain correction profile to a respective optical amplifier (46) of the photonic line system (30) to compensate for the difference.

An apparatus includes a first communication interface configured to be communicatively coupled, via an optical line, to a network device that is disposed in an optical network using wavelength division multiplexing (WDM). The apparatus also includes a second communication interface configured to be communicatively coupled to a router via an Ethernet connection. The apparatus also includes a signal generator operatively coupled to the first communication interface and the second communication interface. The signal generator is configured to generate an Ethernet signal representing at least one attribute of the optical line between the first communication interface and the network device. The second communication interface is configured to transmit the Ethernet signal to the router.

A system for monitoring a signal on an optical fiber includes a fiber optic connector having a housing couplable to a receptacle. An optical fiber that transmits a first optical signal has first fiber core at least partially surrounded by a cladding and has a first end terminating proximate the housing. The first optical signal is transmitted along the first fiber core. An optical tap has a first tap waveguide arranged and is configured to receive at least part of the first optical signal as a first tap signal. The first tap waveguide comprises an output port for the first tap signal for directing the tap signal to a detector unit. In other embodiments, a detector unit detects light from the optical signal that is propagating along the fiber cladding.

A communication device is provided that estimates one or more disturbance values associated with one or more components of the communication device, and adjusts the communication device to change a received power of the output signal. The communication device includes a transmitter having a seed laser configured to provide an amount of bandwidth for an output signal, an Erbium-doped fiber amplifier (EDFA) configured to increase an amplitude of the output signal, and a single mode variable optical attenuator (SMVOA) configured to decrease the amplitude of the output signal.