Optical filter with improved crosstalk rejection

摘要

The specification describes an optical integrated circuit (31) for a wavelength division demultiplexer. The demultiplexer comprises an AWG filter (32) comprising a waveguide grating array between multimoded coupler regions. Crosstalk in the optical signals from the demultiplexer is reduced by integrating a second AWG filter (41-46) on each output waveguide (33-38). In an alternative embodiment the second filter (63-68) is a generalized Mach-Zehnder (M-Z) interferometer filter employing multimode interference filter (MMI) coupler regions connected by a waveguide array (69). <IMAGE>