Design of High-Speed Thin-Film Lithium Niobate Modulator Utilizing Flip-Chip Bonding with Bump Contacts

Abstract

Currently, the high-speed performance of thin-film lithium niobate electro-optic modulator chips is evolving rapidly. Nevertheless, due to the inherent technical limitations imposed by the packaging design and material architecture, the intrinsic electro-optic bandwidth of thin-film lithium niobate electro-optic modulator chips often exceeds the bandwidth of their packaging interfaces, which can constrain the realization of modulation performance. Bump bonding emerges as a high-bandwidth EO interconnection technology, outperforming wire bonding for faster optical communication. In this paper, we present a high-speed thin-film lithium niobate modulator chip tailored for concave–convex bonding, alongside an analysis and design of the chip’s flip-chip bonding packaging. By exploiting the superior electrical characteristics of concave–convex bonding, we effectively mitigate the radio frequency losses of modulator chip and packaging. The simulated half-wave voltage (Vπ) of 3.5 V and E-O modulation bandwidth greater than 150 GHz is obtained for a 0.5 cm long modulator after flip-chip bonding packaging.