Abstract: A dilated N×N optical cross-connect switch suitable for large N exhibits good efficiency (element count) without a significant increase in and reduced small depth (low loss) and crosstalk. The present arrangement consists of six levels of binary trees of 1×2 and 2×1 elements. The first two levels form the input stage, the third and fourth levels form the center stage, and the fifth and sixth levels form the output stage. In each of the input, center, and output stages, the odd number level is formed as a binary tree of 1×2 elements and the even numbered level is formed as a binary tree of 2×1 elements. Each stage is formed by directly joining together the 1×2 element binary tree with the 2×1 element binary tree. In one embodiment, depth is substantially reduced by using a symmetric arrangement of one or more 2×2 elements located in the vicinity of each junction between adjacent stages.

Abstract: A design technique minimizes the loss and ripple in the spectral response of an optical filter formed using a pair of gratings connected by an array of optical elements. This filter can be, for example, two waveguide grating routers (WGRs) connected by an array of waveguides. Each WGR includes two star couplers connected by waveguide grating arms. The smoothest spectral response is achieved for a given set of connecting waveguides, by choosing the number of grating arms less than or equal to filling the star coupler central Brillouin zone made by the set of connecting waveguides resulting in the connecting waveguides neither substantially over- or under-sampling the optical spectrum from the waveguide gratings. Exactly filling the Brillouin zone with the grating arms minimizes the loss, and so is the preferred choice.