Switch for optical signals

An optical switching matrix, comprising first and second pairs of switching elements and a plurality of optical combiners;

• each pair of switching elements comprising a first switching element and a second switching element;
• each switching element comprising:
• a rectangular substrate having a plurality of input ports on a first side, a first plurality of output ports on a second side opposite the first side and a second plurality of output ports on a third side adjacent the first side and the second side;
• and
• a plurality of optical diverters aligned between each input port and a corresponding output port on the second side, each diverter being aligned with a respective output port on the third side and being movable from a first position, in which the diverter allows an optical signal incident from the input port to propagate in a direction toward the respective output port on the second side, to a second position, in which the diverter diverts an optical signal incident from the input port toward a respective output port on the third side;
• for each of the first and second pairs of switching elements, each input port of the second optical switching element being optically coupled to a respective output port of the first optical switching matrix;
• and
• each combiner being coupled to a respective output port of the first pair of optical switching elements and to a respective output port of the second pair of optical switching elements.

A switching fabric for an optical cross-connect switch, the switching fabric comprising a plurality of optical switching matrices, each switching matrix:

• having multiple inter-node input ports and at least one intra-node input port for receiving incoming optical channel signals, the incoming optical channel signals having a wavelength that is particular to that particular switching matrix;
• having multiple inter-node output ports and at least one intra-node output port;
• and
• being operable to switch optical channel signals arriving on any input port to any of a plurality of the inter-node output ports and the intranode output port.

A method of upgrading an optical cross-connect switch having a plurality of switching matrices, each switching matrix assigned to -a respective channel wavelength and having multiple input and output ports, the method comprising the steps of:

• providing each switching matrix with an expansion port;
• providing a plurality of extension switching matrices, each extension switching matrix having multiple input and output ports;
• and
• coupling a respective extension switching matrix to each switching matrix, via said expansion port and at least one of the input ports of the respective extension switching matrix, to form a plurality of expanded switching matrices.