A wavelength router is provided that selectively directs spectral bands between an input port and a set of output ports. The router includes a free-space optical train disposed between the input port and the output ports. The free-space optical train may include air-spaced elements or may be of generally...http://www.google.co.uk/patents/US6798951?utm_source=gb-gplus-sharePatent US6798951 - Wavelength router with a transmissive dispersive element
