Patent ID: 7003198

Claim:
A band filter for filtering an optical signal having components in one or more passbands of the filter, comprising: a first waveguide grating router; a second waveguide grating router; and a plurality of waveguides connecting the first waveguide grating router to the second waveguide grating router, the plurality of waveguides arranged as a waveguide grating, each waveguide having a center wavelength for supporting transmission of an optical signal; wherein the plurality of waveguides is partitioned into at least two sets of waveguides, each set of waveguides corresponding to a particular passband in the band filter, the waveguides in a set having unequal path lengths, and the adjacent waveguides within each set having a path-length difference related to a non-zero integer multiple of a wavelength located between the center wavelengths of the adjacent waveguides.