Silicon Photonics High-Order Distributed Feedback Resonators Filters

High-order distributed feedback resonators realized in silicon-on-insulator technology for the implementation of high-performance integrated optical filters are reported. This approach combines design simplicity and flexibility in a compact footprint with filter transfer functions featuring a flat-top response, large out-of-band rejection of more than 40 dB, ultra-steep roll-off up to 1000 dB/nm, and unprecedented stopband-to-passband ratios up to 600 for high-index-contrast technology. Active control of the coupled cavities through local micro heaters is employed for optimizing the filter response and passband tuning. Exemplary implementations of a box-like transfer function filter with a bandwidth of 25 GHz and of a narrow linewidth 2 GHz filter realized with 6th- and 3rd-order filter designs, respectively, are presented.