A tunable notch filter using high-kt2 lithium niobate resonators toward integration in filter banks

This paper reports on using lithium niobate (LN) resonators for a reconfigurable filter bank. The resonators provide sharp rolloff and bandwidth coverage (from the high electromechanical coupling k_t² of 12.5%) for collocated filters, all in a compact size. The example in this paper is an absorptive notch filter (ANF) that achieves over 35 dB notch rejection. The ANF also demonstrates fine-tuning ability. It can be integrated for a chip-scale reconfigurable filtering platform.