ARRAYED WAVEGUIDE GRATING WITH REDUCED CHANNEL PASSBAND ASYMMETRY

摘要

Roughly described, arrayed waveguide grating apparatus includes one or more input and/or output waveguides which are shaped and oriented such that optical energy communicated with the waveguide array is, within a distance of no more than l mm into the mouth of the waveguide, directed substantially in-line with the optical centerline of the waveguide. In one embodiment, the waveguides are shaped and oriented such that the optical energy enters or exits the waveguide substantially-line with the optical centerline of each waveguide. In another embodiment the waveguides are shaped and oriented such that optical energy is, at the mouth of each waveguide, directed off- axis, and the waveguide includes mode conversion means such that optical energy is directed substantially in-line with the optical centerline within a distance of no more than l mm into the mouth of the waveguide. The mode conversion means may, for example, include a non-adiabatic lateral optical centerline shift.