Multigrating method for flattened spectral response wavelength multi/demultiplexer

The authors successfully demonstrate a new method called a multigrating method, for a flattened spectral response. It uses one-focal-point couplers and several interleaved monomode waveguide gratings. It has a bandwidth of 0.94 nm at -1 db and of 1.8 nm at -20 dB. The loss penalty due to channel flattening is only 2.2 dB.