Wideband tunable integrated microwave photonic filter with dual output on thin-film lithium niobate.

The microwave photonic filter (MPF) has emerged as a promising candidate for next-generation radio-frequency (RF) applications, offering exceptional performance in terms of large instantaneous bandwidth, ultra-wideband frequency tuning, and multifunctionality. However, most existing MPFs provide only a single output port, limiting their applicability in scenarios requiring simultaneous multi-channel responses. Here, we demonstrate a dual-output integrated microwave photonic filter (IMPF) on the thin-film lithium niobate (TFLN) platform, integrating a Mach-Zehnder modulator (MZM), an add-drop microring resonator (MRR), and a notch MRR. By leveraging both the through and drop ports of the add-drop MRR, the IMPF simultaneously achieves bandpass and band-stop responses centered at the same frequency. It exhibits a broad tuning range of 2.6 GHz to 31.5 GHz for the bandpass response and 2.6 GHz to 35.4 GHz for the band-stop response. The proposed IMPF offers both multifunctionality and a wide frequency tuning range, providing a versatile and effective solution for next-generation wireless communication systems.