We disclose a modular fiber-interconnect device that can be used in a ROADM to optically interconnect wavelength-selective switches and optical add/drop blocks thereof. An example module of the modular fiber-interconnect device has seventeen optical ports, each implemented using an MPO connector of the same type. The number of (nominally identical) modules in the modular fiber-interconnect device depends on the degree N of the ROADM and can vary, e.g., from two for N=4 to fourteen or more for N?20. A proper set of duplex optical connections within the ROADM can be created in a relatively straightforward manner, e.g., by running MPO cables of the same type from the wavelength-selective switches and the optical add/drop blocks of the ROADM to appropriate optical ports of the various modules of the modular fiber-interconnect device.

A method may include receiving, by a switching engine, an optical signal that includes a channel. The method may include applying, by the switching engine, a first beam steering grating to direct a first portion of the channel to a first output port. The method may include applying, by the switching engine, one or more second beam steering gratings to direct at least one of a second portion of the channel to a second output port, or a third portion of the channel to a photodetector. The third portion may be approximately less, in power, than 10 percent of the channel.

A programmable multicast switch may include a first set of optical ports and a second set of optical ports. The programmable multicast switch may include a plurality of groups of optical devices optically connected in a cascading arrangement. At least one optical device in each of the plurality of groups may be a tunable optical device. Each group may be connected to an optical port of the first set of optical ports. The programmable multicast switch may include a plurality of controllers to tune each corresponding tunable optical devices. The programmable multicast switch may include a processor to control the plurality of controllers. The programmable multicast switch may include a plurality of optical switches connected to each of the groups of optical devices. Each optical switch of the plurality of optical switches may be connected to an optical port of the second set of optical ports.

A wavelength selective switch (WSS) may include a first port array including input ports, each to launch a respective beam of light, and a dispersive element to separate, in a lateral direction, a beam of light, launched by one of the input ports, into dispersed wavelength channel sub-beams. The WSS may include a switching array to direct the dispersed wavelength channel sub-beams, at respective angles in a vertical direction. The dispersive element may converge groups of dispersed wavelength channel sub-beams in the lateral direction to form wavelength channel sub-beams. The WSS may include a splitting element to split, in the lateral direction, a wavelength channel sub-beam, of the wavelength channel sub-beams, into split wavelength channel sub-beams. The WSS may include switching elements to direct the split wavelength channel sub-beams at respective angles in the vertical direction, and output ports associated with the switching elements.

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 may include receiving, by a switching engine, an optical signal. The optical signal may carry a super-channel that includes a plurality of sub-carriers to be directed toward respective output ports. The switching engine may have a plurality of regions of pixels on which respective sub-carriers, of the plurality of sub-carriers, are incident. The method may include applying, by the switching engine, respective single beam steering gratings to first, overlapping, areas of the plurality of regions of pixels. The method may include applying, by the switching engine, one or more respective pluralities of beam steering gratings to second, overlapping areas of the plurality of regions of pixels. The method may include directing, based on the single beam steering gratings and the one or more pluralities of beam steering gratings, parts of the optical signal toward the respective output ports.

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 radio frequency (RF) beam transmission component having optical inputs and electrical outputs may include a wavelength selective switch (WSS) that has a plurality of optical WSS outputs. Each optical WSS output may be configured to transmit one or more wavelengths of the incoming optical signals. The RF beam transmission component may include a plurality of photodetectors (PD), each photodetector having an optical PD input coupled to one or more of said plurality of optical WSS outputs and a corresponding electrical output of a plurality of PD electrical outputs. The RF beam transmission component may further include a lens that has a plurality of electrical inputs and each electrical input may be electrically coupled to at least one of the plurality of electrical PD outputs. The lens may further have a plurality of electrical lens output ports.

A method and apparatus for approaches for troubleshooting optical networks, particularly ROADM-based networks is described. The method includes designating a first port, of an optical communication node of a transport network, as an ingress for a loop-back optical signal to troubleshoot the transport network, designating a second port, of the optical communication node, as an egress for the loop-back optical signal, and establishing a loop-back connection between the first port and the second port to transport the loop-back optical signal.

A method of validating connections in an optical add/drop multiplexer (OADM) that includes a plurality of modules configured to route optical signals through the OADM, and at least one multi-fiber cable connecting modules of the OADM. A light source coupled to a first port of a first module is controlled to emit a test light. A determination is made whether or not the test light is received at a first photo-detector connected to a second port. Continuity of a connection between the first port and the second port is validated when the test light is received at the first photo-detector.