A dual wavelength Optical Time Domain Reflectometer (OTDR) system, embedded in a network element, includes a first OTDR source for wavelength λ.sub.1; a second OTDR source for wavelength λ.sub.2; an OTDR measurement subsystem adapted to measure backscatter signals λ.sub.1.sub._.sub.BACK, λ.sub.2.sub._.sub.BACK associated with the wavelength λ.sub.1 and the wavelength λ.sub.2; and one or more ports connecting the first OTDR source, the second OTDR source, and the OTDR measurement subsystem to one or more fiber pairs; wherein wavelength λ.sub.1 and wavelength λ.sub.2 are each outside of one or more signal bands with traffic-bearing channels, thereby enabling operation in-service with the traffic-bearing channels.

An optical add-drop apparatus dropping a signal in input optical fibers in an optical cross-connect apparatus or adding a signal into output optical fibers from the cross-connect apparatus, optical cross-connect portions of the cross-connect apparatus connected such that a cross-connect portion internal connection output port is directly connected to an internal connection input port of another cross-connect portion and is indirectly connected via the other cross-connect portion to an internal connection output port of a further cross-connect portion, the add-drop apparatus having: photocouplers connected to part or all of the input fibers connected to each cross-connect portion; and drop signal receiving apparatuses each having optical switches each receiving and alternately selecting a signal output from photocouplers connected to respective different cross-connect portions of the cross-connect portions out of the photocouplers, the drop signal receiving apparatuses selecting a signal of a wavelength for each signal respectively output from the optical switches.

A datacentre for performing a service is provided. The datacentre is configured for receiving an optical signal comprising groups of wavelength bands, A1, A2, A3, . . . , AX, and B, X being an integer, the signal being associated with a request for a service to be executed by the datacentre, the datacentre being configured for executing the service and outputting the result of the service. The datacentre comprises at least one 1:N MD-WSS, having one common port and N tributary ports, where N is an integer and N>1, and a group of at least one server cluster, each comprising a respective transceiver configured to receive and transmit signals on at least some of the wavelength bands.

Apparatus (10) for an optical communications network has optical paths for optical traffic, and optical ports (20,40), one of which is an unused input port (20). A security monitoring system (30) has a blocking part (50) comprising an interface (51) coupled removably to the unused input port (20) to occupy it to prevent unauthorized access. A light source is optically coupled to the interface (51) such that, when the interface is coupled to the unused input port, light can be transmitted through the interface (51) into the unused input port (20). An optical detector (60) can detect light reflected back from the interface (51), and there is alarm circuitry (70) configured to output an alarm signal based on the detecting of the reflected light. This monitoring can help make the node more secure from interference such as the introduction of a noise signal. The system can be passive or active, and does not require a change in the installed node configuration and so can be added easily to existing infrastructure.

This application discloses an optical communications apparatus, which may be a reconfigurable optical add/drop multiplexer. An optical deflection component (211) may perform angle deflection on a plurality of first sub-wavelength light beams to obtain a plurality of second sub-wavelength light beams and a plurality of third sub-wavelength light beams, and propagate the plurality of second sub-wavelength light beams to a second optical switch array (205). A third wavelength dispersion component (206) combines the plurality of second sub-wavelength light beams into a second light beam. A first output component (207) outputs the second light beam from a dimension. A second wavelength dispersion component (208) combines the plurality of third sub-wavelength light beams into a third light beam, and makes the third light beam incident to a third optical switch array (209). A second output component (210) outputs the third light beam to drop a signal.

A method in an optical Wavelength Selective Switch, WSS, for multidirectional switching of optical signals. The optical WSS comprises a reflective element, a first tributary port and a second tributary port. The optical WSS switches (304) an optical signal between the first tributary port and the second tributary port with the reflective element.

An optoelectronic switch comprising: a first plurality of detector remodulators (DRMs) (C3, D1), each DRM having an integer number M of optical inputs and an integer number N of optical outputs; a second plurality of DRMs (C7, D5), each DRM having N optical inputs and M optical outputs; a passive optical switch fabric (C4+C5+C6, D2+D3+D4) connecting the N optical outputs of each of the first plurality of DRMs with the N optical inputs of each of the second plurality of DRMs, the path of an optical signal through the optical switch fabric depending upon its wavelength; wherein each DRM (C3, D1) of the first plurality of DRMs is configured to act as a tunable wavelength converter to select the desired path of an optical signal through the optical switch fabric (C4+C5+C6, D2+D3+D4); and wherein each of the first plurality of DRMs (C3, D1) includes a concentrator, the concentrator configured to aggregate optical signals received from any of the M inputs of that DRM and to buffer them according to the one of the plurality of second DRMs (C7, D5) that includes their destination port.

The present invention relates to adding and dropping signals in a node of an optical network, wherein the node includes a reconfigurable optical add/drop multiplexer (ROADM). The reconfigurable optical add/drop multiplexer (ROADM) comprises output ports and at least one add port connectable to at least one line interface of the network and adapted to receive a modulated optical signal from the line interface. Selection units are connected to one of said add ports and adapted to forward the respective signals to a selected output terminal. A plurality of broadcast units is adapted to broadcast signals forwarded by the selection. Then a multiplexing and selecting device or apparatus selects and multiplexes the optical signals broadcast via broadcast unit output terminals into a plurality of wavelength-division multiplexing (WDM) optical signals and forwards the same to output ports of the reconfigurable optical add-drop multiplexer (ROADM).

An ONU receiving an optical signal from an OLT including PON controllers includes: an optical receiver to convert, into an electric signal, an optical signal having a single optical wavelength set out of plural optical wavelengths; and a control frame extractor to extract and hold wavelength correspondence information indicating correspondence between MAC addresses of the PON controllers received from the OLT and the optical wavelengths. The control frame extractor, when receiving a wavelength switching request, extracts the optical wavelength after wavelength switching instructed in the wavelength switching request, obtains a setting address of the MAC address of the PON controller to which the ONU itself should be connected after the wavelength switching based on the extracted optical wavelength after the wavelength switching and the wavelength correspondence information, and determines whether a malfunction occurs based on a transmission source MAC address stored in a received control frame and the setting address.

An optical communication system includes a plurality of optical system nodes, a plurality of optical space switches and a plurality of optical fibers. The plurality of optical system nodes each includes at least one reconfigurable optical add/drop multiplexer (ROADM). The optical system nodes each have at least one client side port and at least one line side port. Each optical space switch is operatively coupled to the line side port of one of the plurality of optical system nodes. Each of the optical fibers couples one of the optical space switches to another of the optical space switches.