A Reconfigurable Optical Add/Drop Multiplexer (ROADM) node includes a plurality of degrees; and one or more fiber/space switches, wherein each of the plurality of degrees connect to the one or more fiber/space switches, and the one or more fiber/space switches are configured to interconnect any of the plurality of degrees and optionally one or more add/drop components. The plurality of degrees are partially interconnected to one another, while supporting any-to-any interconnect based on a configuration of the one or more fiber/space switches.

An optical add/drop multiplexer includes: a first wavelength selector configured to output an optical signal of each wavelength of an inputted first wavelength multiplexed signal while selecting a path for each wavelength; a measurement circuit configured to measure optical power of an inputted optical signal; and a second wavelength selector including a circuit configured to output an optical signal of each wavelength of the first wavelength multiplexed signal while selecting a path for each wavelength, in place of the first wavelength selector when an abnormality occurs in the first wavelength selector, and a circuit configured to output an inputted second wavelength multiplexed signal for each prescribed wavelength unit to the measurement circuit when the first wavelength selector normally operates.

A WSS is provided. The WSS includes a first common port, a second common port, a grating, a spatial light modulator, and a plurality of branch ports. The first common port is configured to receive a first-band optical signal, and the second common port is configured to receive a second-band optical signal. The grating is configured to perform wavelength demultiplexing on the first-band optical signal and the second-band optical signal, to output a plurality of first optical signals, where the first optical signals are optical signals of a single wavelength.

Reconfigurable optical add-drop multiplexers (ROADMs) includes D optical inputs that receive optical signals, D first optical switching devices, each first optical switching device being associated with one of the D optical inputs, second optical switching devices associated with one of the outputs of a corresponding first optical switching device, each second optical switching device fans-out the optical signal into N multiple signals, third optical switching devices, that combine second output signals received from a corresponding M=D|N of the second optical switching devices, and combining devices that, in use, combine third output signals of N corresponding third optical switching devices and provide a set of D optical outputs of the ROADM and a controller communicably connected to the first, second, third and fth optical switching devices to adjust a switching state thereof.

In an example aspect, an optical switch provided. The optical switch comprises a plurality of reconfigurable add/drop multiplexers (ROADMs), each comprising a plurality of optical line ports and a plurality of add/drop ports. The optical switch also comprises a connection apparatus connecting, for each ROADM, each add/drop port of the ROADM to a port of each of a respective one or more other ROADMs. In another example aspect, a method of configuring an optical switch is provided.