This application example illustrates the design of an Arrayed Waveguide Grating (AWG) simulated by
employing star couplers and straight waveguides. In this example, the multigrating method  is used to achieve a
flattened spectral response. Within this approach, the grating between star couplers is separated into two subgratings.
When these two peaks are slightly different, the final spectral response is flattened.
The setup for the design is composed of two star couplers (left and right) with a central array
of waveguides in between
Random variations of the phase shift in the waveguides simulate phase errors which lead to crosstalk
The effect of nonoptimized waveguide lengths can be analyzed. Results in
are for constant length increments that make spectral responses for even and odd gratings shift to the lower and higher
show the AWG
transfer functions before and after optimization of the waveguide lengths for a flattened response.
Keywords: Electromagnetically Induced Transparency, EIT, Microring, Ring Resonator, Optical planar waveguide components, Photonic Integrated Circuits, PICs
Similar demonstrations are available in VPIComponentMaker Photonic Circuits and on the VPIphotonics Forum.
 A. Rigny, A. Bruno, H. Sik, "Multigrating method for flattened spectral response wavelength multi/demultiplexer," Electron. Lett. 33, 1701-1702 (1997).