Micro-transfer Printed Thin Film Lithium Niobate (TFLN)-on-Silicon Ring Modulator

Thin-film lithium niobate (TFLN) has a proven record of building high-performance electro-optical (EO) modulators. However, its CMOS incompatibility and the need for non-standard etching have consistently posed challenges in terms of scalability, standardization, and the complexity of integration. Heterogeneous integration comes to solve this key challenge. Micro-transfer printing of thin-film lithium niobate brings TFLN to the well-established silicon ecosystem by easy "pick and place", which showcases immense potential in constructing high-density, cost-effective, highly versatile heterogeneous integrated circuits. Here, we demonstrated for the first time a micro-transfer printed thin film lithium niobate (TFLN)-on-silicon ring modulator, which is an important step towards dense integration of performant lithium niobate modulators with compact and scalable silicon circuity. The presented device exhibits an insertion loss of -1.5 dB, extinction ratio of -37 dB, electro-optical bandwidth of 16 GHz, and modulation rates up to 45 Gbits(-1).