Optical switch

An optical switch having a plurality of independently controllable systems 605. Each system comprises an optical signal having at least one component frequency channel which transports between a set of input ports 601 and corresponding output ports 602. A first and second programmable deflection plane 606, 610 to deflect incident beams of the optical signals to form first and second respective deflected beam arrays. A beam steering optical element group to transfer the first deflected beam array from the first deflection plane to the second plane wherein the beam steering group of each system comprises a common plane. The optical switch forms a Fourier conjugate image for the first deflection plane of each system on a common plane which overlaps with the image of at least one other system. The Fourier conjugate images of each system may be different, spatially coincident to each other and formed respective to beam steering optical element groups. The beam steering optical element groups may comprise: 4F arrangements, a Faraday rotator, a polarising beamsplitter, re-mapping devices having mirrors, or grating arrangements such as multiplexers or demultiplexers. The optical switch may comprise transit optical element groups having lenses or reflectors.