A photonic cross-connect arrangement is presented which is able to cope with the transmission of super-channels, wherein complete super-channels are dropped and added to change a direction of transport. At least a cyclic filter is used in a drop-branch of a cross-connect for dividing a super-channel into sub-channels and/or at least a further cyclic filter is used in an add-branch to configure a super-channel.

Provided is a wavelength path communication node device with no collision of wavelengths and routes, capable of outputting arbitrary wavelengths, and capable of outputting them to arbitrary routes. An add/drop multiplexer (11) includes a communication unit (101) that communicates an optical signal with at least one client device and at least one network and a control unit (102) that indicates a transfer destination of the optical signal according to an attribute of the received optical signal to the communication unit (101). The control unit (102) indicates an attenuation amount of the optical signal to the communication unit (101) for each connected device. When a connected device is changed, the control unit (102) instructs the communication unit (101) to change the attenuation amount. The communication unit (101) attenuates the optical signal with the attenuation amount indicated by the control unit (102) and transfers the attenuated optical signal to a transfer destination.

The present disclosure relates to the field of communications technologies, and in particular, to an optical add/drop multiplexer, such that the optical add/drop multiplexer can ensure proper processing of light in two directions. The optical add/drop multiplexer can complete an extraction of a signal in one direction using one microring resonant cavity and two optical circulators, and if a wavelength of a signal in the other direction is the same as a resonant wavelength of the microring resonant cavity, the signal may reenter an optical network after passing through two microring resonant cavities and one optical circulator, and is not affected. Therefore, proper processing of optical signals in the two directions is ensured, and the optical signals in the two directions do not interfere with each other.

A method, computer-readable storage device and apparatus for routing traffic in a reconfigurable optical add-drop multiplexer layer of a dense wavelength division multiplexing network are disclosed. For example, the method determines the reconfigurable optical add-drop multiplexer layer has asymmetric traffic, and routes the asymmetric traffic in the reconfigurable optical add-drop multiplexer layer over a plurality of asymmetrical optical connections, wherein the plurality of asymmetrical optical connections is provided with only uni-directional equipment in the reconfigurable optical add-drop multiplexer layer.

A method for data transport that includes providing a branch terminal between a first and second trunk terminal, wherein a branching unit is present at an intersect between the first and second trunk terminal and the branch terminal. The branching unit includes a reconfigurable add/drop multiplexers (ROADM) at least one attenuator. A signal is sent from a second terminal of the first and second trunk terminal to the branding unit. The signal may include a branch traffic component trunk traffic component. The branching unit includes at least one attenuator for attenuating the trunk traffic component so that the trunk traffic component of the signal cannot be detected at the branch terminal.

A transmission device for which a work path is established in a first degree and a protection path is established in a second degree includes: a switch equipped with a plurality of optical ports; an optical signal generator, optically connected to a first optical port, and configured to generate an optical signal that is transmitted through the work path; and a monitor light generator, optically connected to a second optical port, and configured to generate monitor light by using a wavelength tunable light source. The monitor light generator controls a wavelength of the monitor light to be substantially the same as a wavelength of the optical signal. The switch guides the optical signal that arrives at the first optical port toward the first degree and guides the monitor light that arrives at the second optical port toward the second degree.

A method of monitoring a communications network by monitoring packet errors in one of the paths having at least two optical sections coupled in series with a break in continuity of optical transmission monitoring between the optical sections, and monitoring a transmission quality of each of these optical sections. A state is detected in which the monitored packet errors do exceed an acceptable threshold, but at the same time the transmission quality of each of the optical sections is acceptable, and an indication is transmitted of the detection. This can cause a request for an alternative path for the packets, or cause adapting of these optical sections to reduce bit errors. This can enable handling of potential conflict between packet and optical layers, when the packet layer sees errors but the optical layer indicates no problem.

A procedure for transferring wavelengths, and a system that operates in accordance with the procedure. The system comprises at least one network terminal, each including a switch and a controller. A plurality of wavelength sets are applied to the switch. The controller is arranged to operate the switch such that the switch (a) selects at least one wavelength from at least one of the plurality of wavelength sets, based on electrical monitoring at a port module external to the network terminal, and (b) outputs the at least one wavelength to an output of the at least one network terminal.

In an example, a communication module includes an optical transmitter, an optical receiver, and a periodical filter. The optical transmitter is configured to emit an outbound optical signal. The optical receiver is configured to receive an inbound optical signal. A first frequency of the outbound optical signal is offset from a second frequency of the inbound optical signal by an amount less than a channel spacing of a multiplexer/demultiplexer implemented in an optical communication system that includes the communication module. The periodical filter is positioned in optical paths of both the outbound optical signal and the inbound optical signal and has a transmission spectrum with periodic transmission peaks and troughs. The first frequency of the outbound optical signal may be aligned to one of the transmission peaks and the second frequency of the inbound optical signal may be aligned to one of the transmission troughs, or vice versa.

Methods, systems, and optical power controllers are disclosed. Various problems caused by the use of a single L0 power controller in the prior art are addressed by using first and second L0 power controllers with the first L0 power controller managing first optical components with the optical network, and the second L0 power controller managing second optical components within the optical network.