Chip-based arbitrary radio-frequency photonic filter with algorithm-driven reconfigurable resolution

All programmable microwave photonic filters to date have been limited by the trade-off between the resolution and the operation bandwidth to construct arbitrary filter shapes. Here, we propose a new approach to synthesize a radio-frequency photonic filter with an arbitrary response and reconfigurable resolution through phase-only tailoring, which is implemented in a low-loss photonic chip. Based on an algorithm, incorporating the target transfer function of the filter optimum resolution can be intelligently chosen by tuning the coupling coefficients and the round-trip phase of cascaded ring resonators. We achieved filtering with tunable resolution from 300 MHz to 25 GHz along with various filtering shapes and multiple passbands.