Multi-frequency lithium niobate thin-film resonators

Summary form only given. To satisfy the ever-increasing demand for spectrum, commercial markets desire integrated multi-frequency “band”-select duplexer and diplexer filters, with fractional bandwidth (BW) ranging from 3% to 10% and steep roll-off for high stop band rejection. The achievable bandwidth of such filters is ultimately limited by the electro-mechanical coupling factor (k_t²) of the resonators, while the roll-off is determined by resonator quality factor (Q). Therefore, resonators with both high k_t² and high Q are desired for large BW steep roll-off filters. In this talk I present the fabrication technology and design of thin-film lithium niobate (LN) contour-mode resonators. By carefully positioning the inter-digital transducer (IDT), we 2 achieved CMRs with k_t²×Q of 148 (IDT @ node) and very high k_t² resonators with spur-attenuated response (IDT @ anti-node) [1,2] . We have demonstrated resonators with frequencies ranging from 400MHz to 1.9GHz on a single chip. Additionally, we have demonstrated high optical Q, GHz FSR photonic resonators on the same platform paving the way for high-bandwidth and efficient chip-scale microwave photonics [3].