Patent ID: 7492991
Filing Date: 2009-02-17
Classification: G02B

Abstract:
1. Arrayed waveguide grating apparatus comprising: a waveguide array having a plurality of waveguides arranged to form a diffraction grating and coupling together first and second free space regions, the waveguide array having an input end, an output end, and an array centerline; an input group of at least one input waveguide, each of the input waveguides being disposed and oriented to launch input optical energy across one of the free space regions toward the input end of the waveguide array; and an output group of at least one output waveguide, the output waveguides being disposed and oriented to receive optical energy delivered across one of the free space regions from the output end of the waveguide array to respective positions distributed transversely to the array centerline, each of the input and output waveguides having a respective optical centerline, wherein one of the waveguides in either the input group or the output group is a particular waveguide, and wherein the particular waveguide has a mouth disposed off-center with respect to the array centerline, the particular waveguide being shaped and oriented such that optical energy communicated with the waveguide array is, within a distance of no more than 1 mm into the mouth of the particular waveguide, directed substantially in-line with the optical centerline of the particular waveguide.