Low loss AWG demultiplexer with flat spectral response

An arrayed waveguide grating (AWG) optical wavelength multiplexer/demultiplexer for one of coupling and dividing optical signals of differing wavelengths received at a plurality of input optical waveguides, and outputting the one of coupled and divided optical signals to a plurality of output optical waveguides, respectively, said AWG optical wavelength multiplexer/demultiplexer comprising:

• a first slab waveguide for dividing powers of the optical signals coupled from said plurality of input optical waveguides;
• an arrayed waveguide grating for guiding the optical signals from said first slab waveguide therethrough so that the optical signals have a constant phase difference between adjacent optical waveguides;
• a second slab waveguide for one of coupling and dividing the differing wavelengths of resultant optical signals outputted from said arrayed waveguide grating, and outputting the resultant optical signals to said output optical waveguides, respectively;
• and
• a plurality of tapered waveguides interposed between said second slab waveguide and said output optical waveguides, said tapered waveguides being adapted to obtain a flat spectral response while minimizing an insertion loss wherein said tapered waveguides have an adiabatic structure for preventing a power exchange among waveguide modes during passage of optical signals therethrough.