Optical node architectures for optical communication systems

An optical switching stage, comprising:

• a set of optical input ports,
• a set of optical output ports, and
• S optical switches, numbered 1 to S, wherein S≥3,
• wherein each respective optical switch of the S optical switches comprises:
• a set of optical input ports,
• a set of optical output ports,
• one or more additional optical input ports, and
• one or more additional optical output ports,
• wherein the set of optical input ports of the respective optical switch is a subset of, or is optically connected to, the set of optical input ports of the optical switching stage,
• wherein the set of optical output ports of the respective optical switch is a subset of, or is optically connected to, the set of optical output ports of the optical switching stage, and
• wherein each of the additional optical output ports of the respective optical switch is optically connected, or optically connectable, to one of the additional optical input ports of one of the other optical switches of the S optical switches, and
• wherein for every J from 1 to S:
• a first additional optical output port of the one or more additional optical output ports of optical switch J is optically connected to a first additional optical input port of the one or more additional optical input ports of optical switch J+1, where J+1 is defined as 1 when J equals S.