In an optical fiber monitoring system which detects physical disturbance or other parameters such as temperature or strain of a fiber where a monitor signal is transmitted along the optical fiber and analyzed to detect changes which are indicative of an event, a method is provided for periodically checking proper operation of the optical fiber monitoring system. A fiber disturbance actuator periodically causes a pattern of disturbances of a portion of the fiber at a predetermined location thereon where the disturbance is characteristic of the event to be monitored. The monitor signal is analyzed to detect the pattern of changes and in the event that expected changes are not detected, a warning is issued that the intrusion detection system is not properly operating.

A spatial mode multiplexer for multiplexing optical signals onto different spatial modes includes an optical path for directing a probe signal through a mode converter of the multiplexer. A spatial profile of an optical phase of the probe signal is detected e.g. by splitting the reference signal into monitoring and reference paths to produce an interference pattern that can be captured and processed to control the spatial mode converters.

For determining equalization parameters for performing equalization for optical signals transmitted by a first device to a second device via an optical band-pass filter, the second device being configured for receiving optical signals output by said optical band-pass filter and transmitted by the first device on a carrier wavelength when said carrier wavelength is comprised in the passband of the optical band-pass filter, said carrier wavelength and/or said passband of the optical band-pass filter being a priori unknown, a monitoring device performs: determining information representative of a level of detuning between the carrier wavelength of the optical signals and the nominal wavelength of the optical band-pass filter; and determining said equalization parameters, on the basis of said determined information representative of the level of detuning between the carrier wavelength of the optical signals and the nominal wavelength of the optical band-pass filter.

A method and system for adaptive quantum information processing can be provided by determining a state of a quantum channel governing an environment with a tomography module. Next a scope of the quantum channel can be calculated with a scope algorithm module. Finally, an optimization module can be utilized to optimize the way to quantum mechanically represent information to be transmitted through the quantum channel based on the scope.

An optical wavelength multiplexing device includes: a wavelength selective switch including a first input port for receiving an optical signal, a second input port for receiving a monitoring signal, output ports for outputting the optical signal or the monitoring signal, and an adjustment unit that adjusts a level of the optical signal or the monitoring signal at one of the output ports; a measurement unit that measures an output level of the monitoring signal at one of the output ports; and a control unit that specifies an unused output port of the output ports as a monitoring target port; sets a specific adjustment amount to the monitoring target port; outputs the monitoring signal to the monitoring target port; and determines whether the monitoring target port has an abnormality, based on the output level at the monitoring target port and an estimated output level at the monitoring target port.

A system and method are presented for coupling OAM optical beams to optical fibers. The system may include, for instance, an OAM beam generator, for receiving one or more of a plurality of input signals, and generating a different OAM mode signal for each input signal. The OAM beam generator may further be operative to adjust a location and/or an exit angle of the one or more OAM mode signals before sending the one or more OAM mode signals to a beam combiner that combines the one or more OAM mode signals into a combined mode OAM transmission. The system may further include a controller in communication with at least one crosstalk estimate sensor and the at least one OAM beam generator, the controller operative to optimize the crosstalk estimate by receiving the crosstalk estimate for one of the OAM mode signals, and sending control instructions instructing the OAM beam generator to adjust a location and/or an exit angle of the one or more OAM mode signals to reduce the crosstalk estimate.

A preFEC BER of a selected optical link is determined. A FEC Detected Degrade (FDD) threshold, FEC Excessive Degrade (FED) threshold, and FEC limit threshold are obtained for the selected optical link. The FDD threshold is less than the FED threshold and the FED threshold is less than the FEC limit. Based on the FDD threshold, FED threshold, the FEC limit, and a determination that a postFEC BER==0, it is determined whether a link down condition of the selected optical link can be asserted or de-asserted.

A nonlinear compensation unit (300) includes a first compensation unit (350) and a second compensation unit (360). The first compensation unit (350) compensates for each of two polarization signals E.sub.x and E.sub.y so as to cancel a first amount of phase rotation which is the amount of phase rotation calculated based on the signal strength of the two polarization signals E.sub.x and E.sub.y. The second compensation unit (360) compensates for each of the two polarization signals E.sub.x and E.sub.y so as to cancel a second amount of phase rotation which is the amount of phase rotation calculated based on the perturbative component of the two polarization signals E.sub.x and E.sub.y. The first compensation unit (350) includes a strength calculation unit (302), a first filter unit (304), and a first phase modulation unit (306). The second compensation unit (360) includes a perturbative component calculation unit (316), a second filter unit (318), a second phase modulation unit (322), and a third phase modulation unit (330).

In an optical network system based on a wavelength division multiplexing system using a flexible frequency grid, with the diversification of optical modulation methods, the management burden on an optical network management device increases, and its control becomes complicated; therefore, an optical network system according to an exemplary aspect of the present invention includes an optical network management device configured to receive a traffic demand, design an optical path capable of accommodating the traffic demand, and create optical path design information of a design result; and an optical node device configured to be used for creating the optical path, wherein the optical node device calculates an allocable bandwidth from the optical path design information and optical node device information on a configuration of the optical node device, and the allocable bandwidth is an optical frequency bandwidth of a generable optical path that the optical node device is capable of generating, and the optical network management device sets, from among optical path candidates having the allocable bandwidth, a desired optical path that matches the optical path design information.

Disclosed is a method of characterizing a multimode optical fiber link including a light source and two or more multimode fibers. The method includes a step of characterizing each of said multimode fibers using a measurement of the Dispersion Modal Delay (DMD) for each of said multimode fibers, and delivering, for each of said multimode fibers, at least three fiber characteristic curves as a function of a radial offset value r; a step of characterizing the light source by at least three source characteristic curves showing at least three parameters of the source as a function of a fiber radius r and obtained by a technique similar to the DMD measurement; and a step of computing an Effective Bandwidth (EB) of the link, comprising calculating a transfer function using both each of said source characteristic curves and each of said at least three fiber characteristic curves for each of said multimode fibers.