Patent ID: 7283700

Claim:
A wavelength router formed by a planar optical imaging arrangement comprising an input stage, an output stage, and a composite lens connected between the two stages, wherein: the input stage is a waveguide grating router whose output focal circle is characterized by a central zone of minimal loss variation caused by the router efficiency variation; the composite lens is a waveguide arrangement characterized by a single input aperture and two separate output apertures, wherein the input aperture covers said zone of minimal loss variation; the output stage includes two waveguide grating routers, each connected to one of the two output apertures of the lens; the input grating and the output gratings have substantially opposite dispersions, so that the wavelength response to an input signal applied to the input router is essentially two sets of stationary images, respectively produced on the two focal circles of the two output routers, wherein the images of each set are produced by different diffraction orders of the input router; and, each output router includes several output waveguides, each connected at the location of one of said stationary images.