A method of obtaining a measure of asymmetry between optical fibers of a forward and reverse paths is provided in order to synchronize clocks of optical nodes connected by asymmetrical optical fiber paths. The method includes receiving, at first and second arrival times, from a first optical network device, a first optical signal transmitted on a first optical fiber and a second optical signal transmitted on a second optical fiber, calculating a first time difference between the second arrival time and the first arrival time. The method includes determining a measure of asymmetry between the first optical fiber and the second optical fiber based on the first time difference and a second time difference between a first time of transmission by the first optical network device of the first optical signal and a second time of transmission by the first optical network device of the second optical signal.

A method of obtaining a measure of asymmetry between optical fibers of a forward and reverse paths is provided in order to synchronize clocks of optical nodes connected by asymmetrical optical fiber paths. The method includes receiving, at first and second arrival times, from a first optical network device, a first optical signal transmitted on a first optical fiber and a second optical signal transmitted on a second optical fiber, calculating a first time difference between the second arrival time and the first arrival time. The method includes determining a measure of asymmetry between the first optical fiber and the second optical fiber based on the first time difference and a second time difference between a first time of transmission by the first optical network device of the first optical signal and a second time of transmission by the first optical network device of the second optical signal.

A signal processing device includes: a first conversion circuit that, among optical signals of channels included in wavelength division multiplexed optical signal, converts electric field signals that indicate electric field components of the optical signal of a predetermined channel, from time domain signals into frequency domain signals; a filter that passes the electric field signals converted into the frequency domain signals with a passband; a second conversion circuit that converts the electric field signals, from the frequency domain signals into the time domain signals; an amplitude measurement circuit that measures first amplitudes of the electric field signals and second amplitudes of the electric field signals; and a notification circuit that notifies a power measurement device that measures power of the optical signal of the predetermined channel, of the first amplitudes and the second amplitudes used in correction of a measurement error of the power of the optical signal.

Disclosed herein are methods and systems for computing a launch power for an optical node by collecting data for an optical network segment and inputting the collected data and first power spectral density values into a machine learning model which are used to compute a first non-linear interference value. A first generalized-optical signal-to-noise ratio value is computed using the computed first non-linear interference value and amplified spontaneous emission values. At least one second generalized-optical signal-to-noise ratio value is computed using at least one second non-linear interference value, computed using at least one second power spectral density values, and the amplified spontaneous emission values. A highest generalized-optical signal-to-noise ratio value is determined by comparing the first generalized-optical signal-to-noise ratio value and the at least one second generalized-optical signal-to-noise ratio value. A launch power is computed using the power spectral density values associated with the highest generalized-optical signal-to-noise ratio.

In one embodiment, information passing mechanism between the two connected optical transceivers is provided. Within the first optical transceiver, Rx 1 calculates the current condition of the uplink channel and passes this information together with the condition of the downlink channel that it receives from Tx 2 to Tx 1. The Tx 1 uses the downlink channel condition that it receives from the Rx 1 to generate signal with appropriate modulation format, shaping factor, baudrate and coding scheme for maximizing the downlink's capacity. The Tx 1 then transmits this information together with the uplink channel condition received from Rx 1 to Rx 2. The Rx 2 uses the information about the modulation format, baudrate, shaping factor and coding scheme that it receives from Tx 1 for the reception of information-bearing signal. The Rx 2 then calculates the transmission channel condition of the downlink channel and passes this information together with the uplink channel condition that it receives from Tx 1 to Tx 2. The Tx 2 then uses the uplink channel condition that it receives from the Rx 2 to generate signal with optimized modulation format, shaping factor, baudrate and coding scheme for maximizing the uplink's capacity. The information exchange process between the two connected optical transceivers then repeats in an endless loop.

A communication apparatus includes a plurality of devices, each of the plurality of devices includes a monitoring unit configured to monitor at least one other device to detect an error that has occurred in the other device, and each of the plurality of devices is monitored by at least one other device.

An optical signal processing method, a control unit, an optical transmission unit and a storage medium are disclosed. The optical signal processing method includes: acquiring an OSNR value from an optical receiving unit (S100); acquiring a spectrum shaping adjustment parameter according to the OSNR value (S200); and sending the spectrum shaping adjustment parameter to an optical transmission unit to adjust a filtering parameter of a shaping filter of the optical transmission unit, so that the optical transmission unit adjusts a spectrum waveform of an optical signal by utilizing the shaping filter after adjustment (S300).

An optical communications system includes a modulator/demodulator (modem) to transmit outgoing communications data and to receive incoming communications data in a transceiver. A main detector is coupled to the modem to convert an optical signal representing the incoming communications data to an electrical signal for the modem. An adaptive data rate processor monitors the electrical signal from the main detector to determine a current power level for the optical signal. The adaptive data rate processor dynamically adjusts a data rate of the modem based on the determined current power level of the optical signal.

A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control channel information to a corresponding leaf node, and such information may be used by the leaf node to configure the leaf node to have a desired bandwidth or capacity.

Systems and methods for calibrating a Raman amplifier in a photonic line system of an optical network are provided. A method, according to one implementation, includes the step of setting the gain of a plurality of pump lasers of a Raman amplifier to a safe level. For example, the pump lasers are configured to operate at different wavelengths. Also, the Raman amplifier is connected to a fiber span having a specific fiber-type. The safe can be defined as a level that keeps adverse intermodulation effects below a predetermined threshold regardless of the specific fiber-type. In addition, the method includes the step of increasing the gain of the pump lasers without prior knowledge of the specific fiber-type of the fiber span while keeping the adverse intermodulation effects below the predetermined threshold.