Patent ID: 7409123

Claim:
An optical device, comprising: an echelle grating and input waveguide arranged such that the echelle grating receives an input signal that exits from a port of the input waveguide, the echelle grating having a grating axis and being configured to reflect the input signal such that when the input signal has a plurality of channels, the input signal separates into output signals that each includes a different one of the channels; and a plurality of output waveguides that each includes a port positioned to receive one of the output signals, the output waveguides including central waveguides, the central waveguides being the three centermost output waveguides when the total number of output waveguides is odd and being the two centermost output waveguides when the total number of output waveguides is even, and the central waveguides positioned such that the grating axis passes through the port associated with one of the central waveguides or passes between the ports associated with the central waveguides.