A network control apparatus includes a processor. The processor calculates a first OSNR corresponding to an allowable limit BER from an OSNR yield strength curve of a transmission end in a node of a transmission end. The processor acquires a reception BER of a second node of a reception end, and calculates a second OSNR corresponding to the reception BER from the OSNR yield strength curve of the transmission end. The processor calculates a first noise intensity corresponding to the allowable limit BER from the first OSNR. The processor calculates a second noise intensity corresponding to the reception BER from the second OSNR. The processor calculates a noise intensity margin, based on the first noise intensity and the second noise intensity.

An apparatus includes a reconfigurable optical add/drop multiplexer (ROADM) having an input port to receive a first optical signal from a second device. The ROADM also includes a first wavelength selective switch (WSS), in optical communication with the input port, to convert the first optical signal into a second optical signal, a loopback, in optical communication with the first WSS, to transmit the second optical signal, and a second WSS, in optical communication with the loopback, to convert the second optical signal to a third optical signal and direct the third optical signal back to the second device via the input port.

Devices, computer-readable media and methods are disclosed for determining reachability for a wavelength connection in a telecommunication network. For example, a processor deployed in a telecommunication network may calculate a fiber loss on a link in the telecommunication network using optical power measurements and determine that a destination node of a wavelength connection is not reachable via a path that includes the link based upon the fiber loss of the link that is calculated. In one example, the determining is based upon a number of links in the path, an effective fiber loss for each link in the path, a penalty for nodes in the path, and an acceptable loss value. The processor may further perform a remedial action in response to determining that the destination node of the wavelength connection is not reachable via the path.

A wavelength debugging method of multi-channel optical module includes: determine the initial temperature of TEC, and plot the temperature-optical power curve of each channel; obtain temperature T.sub.up and T.sub.down corresponding to upper and lower limit values of the target wavelength of each channel and the left and right security boundary temperatures T.sub.left and T.sub.right of each channel; compare T.sub.up, T.sub.down, T.sub.left, T.sub.right of each channel, when the product is qualified, record the middle two values in descending order as T.sub.1 and T.sub.2, respectively; compare the size of T.sub.1 and T.sub.2 of each channel, when the product is qualified, take the maximum value of T.sub.1 of each channel as T.sub.down, and take the minimum value of T.sub.2 of each channel as T.sub.up, the final setting temperature of TEC is calculated as T=(T.sub.down+T.sub.up)/2, and the corresponding wavelength for each channel at this temperature T is the wavelength after debugging for each channel.

A fibre-optic measurement system equipped with a controlled light generation system (1) and a receiving system (2) connected via an optical path which comprises a directional device (4) and which, in addition, has a processing unit (9) for controlling the light generation system (1) and for receiving and processing the signal from the receiving system (2), according to the invention, it is characterized by the fact that it has a selective mode device (5) and is adapted to be connected to a fibre-optic telecommunications network by a selective mode device (5) and the processing unit (9) is adapted to implement the OFDR and/or COTDR measurement technique for measuring changes in the optical distance and processing them into one or more parameters. Moreover, the object of the invention is also the method of adaptation of a telecommunications network into a sensor network and a fibre-optic measurement and communication system.

A wavelength control system, method, and apparatus are described in the present disclosure. An example method include: adjusting powers of subcarriers on a super channel to a same power, where the subcarriers of the super channel includes consecutive subcarriers, a subcarrier i1, a subcarrier i, and a subcarrier i+1; obtaining Q values of the subcarrier i1 and the subcarrier i+1, where the Q values indicate performance of the subcarriers; calculating a Q value difference between the Q value of the subcarrier i+1 and the Q value of the subcarrier i1, and calculating a difference between the Q value difference and a pre-obtained reference value of the subcarrier i; determining whether the absolute value of the difference is not less than the pre-obtained allowable frequency offset value, and adjusting a center wavelength of the subcarrier i according to the difference.

A multiport optical switch is used to controllably select a specific incoming optical signal that is to be processed by an associated optical channel monitor (OCM). The OCM includes a tunable optical filter and photodetector arrangement, and is configured to measure the optical spectrum of the incoming optical signal and extract information associated with the various optical channels forming the incoming optical signal (i.e., power, wavelength, OSNR, etc., per channel in the signal). The OCM also includes a processor that generates a pair of output control signals, a first signal to control the wavelength scanning process of the tunable optical filter and a second signal to control the setting of the multiport optical switch. The second signal may also be used to perform detuning of a selected input of the multiport optical switch, providing the ability to adjust the power level of an input signal prior to entering the OCM.

A wavelength-setting auxiliary device according to an embodiment of the inventive concept includes an optical wavelength analyzer configured to transmit a test signal having a first wavelength to an optical line terminal, and to execute a central wavelength detection algorithm based on a result of detecting power of a return signal for the test signal to set optical wavelength information of a tunable optical module, and a connector connected to the tunable optical module for interfacing data transmitted between the optical wavelength analyzer and the tunable optical module.

Example embodiments of the present invention relate to optical wavelength directing devices used to construct compact optical nodes.

A method for enhancing optical signal-to-noise ratio measuring precision by correcting spectral resolution is provided, which can obtain optical signal-to-noise ratio with enhanced measuring precision, by measuring actual power of broad spectrum signals in a certain bandwidth, determining the sum of the power of the sampling points for the broad spectrum signals in the bandwidth by using an optical spectrum analyzer, obtaining the corrected resolution of the optical spectrum analyzer, and replacing the setting resolution of the optical spectrum analyzer with the corrected resolution. The method can effectively solve the problem of large OSNR measuring error resulted from the difference between the setting resolution and the actual resolution of optical spectrum analyzer. The method is applicable to correct resolution for all optical spectrum analyzers, and also applicable to enhance the measuring precision for all OSNR measuring methods based on spectrum analysis, and has the advantages of easiness to handle and implement.