Reconfigurable Microwave Photonic Filters with Ultrasteep Roll‐Off Based on Optical Microcombs

ABSTRACT Microwave photonic (MWP) filters are essential components in microwave systems due to their wide bandwidth, low loss, and immunity to electromagnetic interference. Steep roll‐off is critical for precise spectral shaping and effective interference suppression, yet conventional MWP filters face challenges in simultaneously achieving steep transitions and high reconfigurability. Here, reconfigurable MWP filters with steep roll‐off based on a transversal filter structure using an optical microcomb source are demonstrated. Four different types of single‐band MWP filters with ultrahigh roll‐off rates up to ∼32.6 dB/GHz and a minimum 20‐dB shape factor of ∼1.15 are achieved. In addition, simply through programming tap coefficients, band‐pass filters with tunable centre frequencies ranging from 5 to 15 GHz and dual‐band MWP filters with various filter responses are demonstrated without changing any hardware, where steep roll‐off is also validated. The reconfigurable MWP filters with steep roll‐off offer a stable and versatile solution for applications requiring high spectral selectivity, such as next‐generation wireless networks, high‐resolution radar imaging, and advanced biomedical sensing.