Optical processing

An optical routing module having at least two inputs and at least one output and operable to select between the inputs, the module comprising:

• a reflective Spatial Light Modulator (SLM) having a two-dimensional array of controllable elements, a dispersion device, an optical device, and circuitry constructed and arranged to control the controllable elements of the SLM to determine what is output, wherein:
• the dispersion device is disposed to receive light from said at least two inputs and is constructed and arranged to angularly disperse light beams of different centre wavelengths;
• the optical device is disposed to receive the angularly dispersed light beams from the dispersion device, to direct the light beams to respective different two-dimensional groups of controllable elements of the SLM and to spatially distribute the light beams from the dispersion device by wavelength as input light beams both across the SLM and within each of the two-dimensional groups, thereby to form light beams having spatially separated centre wavelengths at the SLM;
• the SLM is disposed to receive one or more input light beams having spatially separated centre wavelengths from the optical device and to form one or more emergent reflected output light beams, and is operable to steer the one or more emergent reflected output light beams away from the input light beams;
• and
• the optical device and dispersion element are further disposed such that all wavelengths selected for routing to an output are combined into a respective common beam.