Silica-Based Arrayed Waveguide Grating with Flattened Spectral Response Using a Multimode Interference Coupler

We designed and fabricated an arrayed waveguide grating based on silica-on-silicon materials with flattened spectral response by adding a multimode interference coupler in the input region. The theoretical analysis and calculation are given. The device has worked effectively and has been tested with the passband 0.43 nm at 1 dB, 0.72 nm at 3 dB and 1.56 nm at 20 dB respectively, at a cost of power penalty of about 1.5 dB. The crosstalk is less than -30 dB, owing to the high-resolution photomask and well-controlled fabrication processes.