The disclosed system implements a bandwidth-reconfigurable optical interconnect, which couples optical signals between N interconnect inputs and N interconnect outputs. The system includes an arrayed waveguide grating router (AWGR), which provides cyclic, single-wavelength, all-to-all routing between N AWGR inputs and N AWGR outputs. The system also includes a wavelength-insensitive switch, which provides all-wavelength, all-to-all connectivity between N wavelength-insensitive inputs and N wavelength-insensitive outputs. The system additionally includes a wavelength-selective input switch, which selectively directs up to L wavelengths from each of the N interconnect inputs into a corresponding input of the wavelength-insensitive switch, wherein unselected wavelengths from each of the N interconnect inputs pass into a corresponding AWGR input. Finally, the system includes a wavelength-selective output switch, which selectively directs up to L wavelengths from each of the N wavelength-insensitive outputs into a corresponding interconnect output, wherein each of the N AWGR outputs pass into a corresponding interconnect output.

A tunable optical device uses a diffraction grating to angularly disperse a collimated beam carrying multiple wavelengths into multiple individually collimated wavelength beams, and then refocuses each of the individual collimated beams to its own focusing point on a moving plate that is located in the region of the focus plane. One or more reflective dots on the moving plate then selectively reflect particular wavelength(s) back to a first output port. The unselected wavelengths are transmitted through the moving plate, where they are then recombined and sent to a second output port. In a typical optical network architecture, the selected wavelength(s) could be viewed as the dropped traffic at a node of the optical network, while the unselected wavelengths could be viewed as the express traffic that is being passed to another node of the network. The device can also be used as a wavelength or beam combiner as well as a splitter.

An optical transmission device that transmits an optical signal in a specified wavelength band includes: a receiver, a monitor light unit, a wavelength selective switch and a memory. The receiver receives the optical signal. The monitor light unit outputs monitor light of a wavelength allocated outside of the specified wavelength band. The wavelength selective switch outputs the optical signal via a first port and outputs the monitor light via a second port. The memory stores information that indicates an optical power loss of a route through which the monitor light is transmitted.

A method (10) of controlling optical signal power levelling in an optical communication network node configured to apply an optical attenuation, α, to a pass-through optical signal. The method comprises: a. performing the following steps i. to iii. until an attenuation variation value, Δα, is greater than a preselected attenuation variation threshold value (18), Δα.sub.TH: i. measuring (12) an optical signal power of an optical signal; ii. calculating (14) a difference, ΔP, between the measured optical signal power and a target optical signal power; iii. calculating (16) a value for the attenuation variation, Δα, to be applied to the optical attenuation taking account of ΔP; b. obtaining (20) a current value of the optical attenuation, α.sub.n, and obtaining (22) a new optical attenuation value, α.sub.n+1, in dependence on the current value of the optical attenuation, a current value of the attenuation variation, Δα.sub.n, and at least an earlier value of the attenuation variation, Δ.sub.αn−1; and c. generating (24) a control signal arranged to configure the node to apply the new optical attenuation value, α.sub.n+1.

A fast optical switch can be fabricated/constructed, when vanadium dioxide (VO.sub.2) ultra thin-film or a cluster of vanadium dioxide particles (less than 0.5 microns in diameter) embedded in an ultra thin-film of a polymeric material or in a mesh of metal nanowires is activated by either an electrical pulse (a voltage pulse or a current pulse) or a light pulse just to induce rapid insulator-to-metal phase transition (IMT) in vanadium dioxide ultra thin-film or vanadium dioxide particles embedded in an ultra thin-film of a polymeric material or in a mesh of metal nanowires. The applications of such a fast optical switch for an on-Demand optical add-drop subsystem, integrating with or without a wavelength converter are also described.

A method for transmitting data over an optical communication system is performed by sequentially tuning a laser beam among a plurality of optical wavelengths. At least one data signal is modulated onto the plurality of optical wavelengths by sequentially switching the modulation of the data signal among the plurality of optical wavelengths such that at any given time the data signal is only modulated onto a single one of the optical wavelengths. The sequential switching is performed at a rate equal to or greater than a response time of one or more optical amplifiers used for amplifying the optical wavelengths.

An apparatus is described. The apparatus comprises a downstream wavelength selective switch having an input port, an optical path operable to carry an optical signal, an optical source providing amplified spontaneous emission (ASE) light, an optical switch having a first input coupled to the optical path, a second input coupled to the optical source and receiving the ASE light, and an output coupled to the input port of the downstream wavelength selective switch. The optical switch couples either the first input or the second input to the output. Further included is a photodiode operable to monitor the optical signal, detect an optical loss of signal of the optical signal, and output a switch signal to the optical switch such that the optical switch couples the second input receiving the ASE light to the output whereby the ASE light is directed to the input port of the downstream wavelength selective switch.

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.

A network capable of being used in a datacenter is described. In some embodiments, the network can comprise a set of optical fiber rings, wherein each optical fiber ring carries data traffic on one or more wavelengths, and wherein each optical fiber ring is partitioned into multiple sectors. A reconfigurable optical add-drop multiplexer (ROADM) can be coupled to at least one optical fiber in each of at least two sectors. An electro-optical-switch can be coupled to each ROADM in each of the at least two sectors. A set of switches can be coupled to each electro-optical-switch in each of the at least two sectors. The set of switches can comprise a first layer of aggregation switches that is coupled to a second layer of edge switches, wherein the edge switches can be coupled to servers in a datacenter.

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.