Patent ID: 7715671
Filing Date: 2010-05-11
Classification: G02B

Abstract:
1. An optical multiplexer/demultiplexer comprising: an asymmetric Mach Zehnder interferometer (MZI) optically coupled to an arrayed waveguide grating (AWG), wherein the MZI includes a first coupler for dividing an input optical signal between a pair of waveguide arms having an optical path length difference between them, disposed such that the pair of waveguide arms cross each other substantially without optical coupling between them, the waveguide arms being joined by a second coupler coupled to the AWG, for optically coupling an optical signal into the AWG, wherein the waveguide arm with the longer optical path length crosses over the waveguide arm with the shorter optical path length between the first and second couplers, so that light from the waveguide arm with the longer optical path length is coupled to a slab region of the AWG at a location closer to a longer path length region of the AWG waveguide grating, while light from the waveguide arm with the shorter optical path length is coupled to the slab region at a location closer to a shorter path length region of the AWG waveguide grating, and together the pair of waveguide arms define a first curvature, and the AWG is adapted to spatially separate an optical signal of multiple wavelengths into optical channels having a predefined channel spacing between them, the AWG defining a second curvature, opposite to the first curvature, and wherein the MZI has a free spectral range (FSR) substantially equal to the channel spacing of the AWG.