This method includes optimizing, by a gradient descent method, a first parameter used in back propagation processing and associated with XPM and a second parameter used in the back propagation processing and associated with SPM and XPM, wherein the back propagation processing is processing to estimate a waveform at a time of transmission by alternately calculating linear terms and nonlinear terms in a nonlinear Schr?dinger equation after receiving an optical signal whose waveform shape changed in a transmission line and digitizing a waveform of the received optical signal, and correct, for each channel of plural channels in the transmission line at a time of wavelength-division multiplexing transmission, waveform distortion caused by SPM that occurs in the channel and waveform distortion caused by XPM that occurs in relation with channels other than the channel; and executing the back propagation processing by using the optimized first and second parameters.

A wireless communications system includes a baseband processing unit (BBU), an optical multiplexer, M (greater than or equal to 2) first optical transceivers, and a wireless radio frequency apparatus, where the M first optical transceivers are provided between the BBU and the optical multiplexer, and operating wavelengths of the M first optical transceivers are different from each other. The wireless radio frequency apparatus includes M remote radio units (RRUs), M second optical transceivers separately corresponding to the M first optical transceivers, and at least one optical splitter, where the M second optical transceivers are separately connected to the M RRUs, and an operating wavelength of a first optical transceiver matches an operating wavelength of a corresponding second optical transceiver. The M second optical transceivers are connected to a same optical fiber by the optical splitter, and the optical fiber is connected to the optical multiplexer and the optical splitter.

In an optical transceiver, an optical transmitter coupled to a reconfigurable optical channel-add apparatus has first and second add paths, an add micro-ring resonator, and first and second optical attenuators, reconfigurable to selectively block an optical channel from an optical transmitter in one of the first and second add paths. The add micro-ring resonator is reconfigurable selectively to add an optical channel from the first add path to an optical waveguide to travel towards the first add-drop port or to add an optical channel from the second add path to the optical waveguide to travel towards the second add-drop port. An optical receiver is coupled to a reconfigurable optical channel-drop apparatus having a drop micro-ring resonator, and first and second drop paths. The drop micro-ring resonator is reconfigurable selectively to drop an optical channel travelling from the first add-drop port from the optical waveguide to the first drop path or to drop an optical channel travelling from the second add-drop port from the optical waveguide to the second drop path.

An FBG element is configured to apply a phase shift to at least one of an input optical signal, a first pump light, and an idler signal between stages of a phase sensitive amplifier. The FBG element is apodized using a trapezoidal apodization function over the length of the first FBG element to enable tuning of the phase shift over a range of 2 radians.

Aspects of the subject disclosure may include, for example, identifying network elements of a wavelength division multiplexing (WDM) domain of an optical waveguide communication system that includes a group of optical-add-drop multiplexor (OADM) devices. Operations are observed for the WDM domain configured to deliver communication services configured for simultaneously transporting independent signals across a network of single optical waveguides. A demand for optical waveguide communication services is determined and the WDM network is configured according to the optical fiber communication link requirement and according to the observations. The configured WDM network includes at least one OADM device of the group of OADM devices configured to provide a WDM cross-frequency network path of the configured WDM network. Other embodiments are disclosed.

A transmission and reception apparatus, includes a processor and a processing device coupled to the processor, wherein the processor is configured to detect insertion of a pluggable module, issue, when the insertion of the pluggable module is detected, an instruction to the processing device to generate a first test signal to be supplied to the pluggable module, extract an alternating current component from a first monitoring result of the first test signal by the pluggable module and acquiring pulse width information at a plurality of phase points, and set a phase point determined based on the pulse width information as an optimum phase value to the processing device.

In order to prevent, without significantly reducing the power of a transmission path, a signal unnecessary for a branch station from being intercepted at the branch station, a node apparatus comprises: a first optical unit that outputs a first optical signal received from a first terminal station and addressed to a second terminal station and also outputs a second optical signal received from the first terminal station and addressed to a third terminal station; and a second optical unit that receives the first and second optical signals outputted from the first optical unit, optically removes a portion of the spectrum of the first optical signal, thereby generating a fourth optical signal, and passes the second optical signal as it is, thereby transmitting the second optical signal together with the fourth optical signal to the third terminal station.

A wireless communications system includes a BBU, an optical multiplexer, M (greater than or equal to 2) first optical transceivers, and a wireless radio frequency apparatus, where the M first optical transceivers are provided between the BBU and the optical multiplexer, operating wavelengths of the M first optical transceivers are different from each other. The wireless radio frequency apparatus includes M RRUs, M second optical transceivers separately corresponding to the M first optical transceivers, and at least one optical splitter, where the M second optical transceivers are separately connected to the M RRUs, and an operating wavelength of a first optical transceiver matches an operating wavelength of a corresponding second optical transceiver. The M second optical transceivers are connected to a same optical fiber by the at least one optical splitter, and the optical fiber is connected to the optical multiplexer and one of the at least one optical splitter.

An optical transmission device includes an optical amplifier that optically amplifies a wavelength multiplexing signal which is input, a wavelength selective switch that splits, inserts, or transmits an optical signal of any wavelength of the wavelength multiplexing signal, an optical channel power monitor that detects power of each channel of the wavelength multiplexing signal which is input and the wavelength multiplexing signal which is output, and a controller that calculates an amount of change in the optical signal of each channel in which a gain of each channel between an input and an output to and from the device is steady, and adjusts an amount of attenuation of the wavelength selective switch, based on the power of each channel of the wavelength multiplexing signal that is detected by the optical channel power monitor.

Systems and methods are implemented at an Optical Add/Drop Multiplexer (OADM) node using virtual sections to provide sectional control over an optical link over a foreign-controlled optical network. The systems and methods include virtually splitting the optical link at a shelf processor associated with the OADM node; in a non-fault condition, obtaining and storing a power snapshot of the optical link and associated virtual sections thereon, from an optical spectrum monitor; responsive to a fault on one or more virtual sections of the virtual sections, obtaining a current power snapshot of the optical link and the associated virtual sections; and comparing the stored power snapshot and the current power snapshot of the one or more virtual sections and providing a fault alarm for the one or more virtual sections based on the comparing to a control plane for management thereof.