Hu, YaowenYu, MengjieShams Ansari, AmirhassanSinclair, NeilHolzgrafe, JeffreyPuma, EricZhang, MianShao, LinboLoncar, Marko2023-09-272021-11-24Hu, Yaowen, Mengjie Yu, Amirhassan Shams Ansari, Neil Sinclair, Jeffrey Holzgrafe, Eric Puma, Mian Zhang et al. "On-chip electro-optic frequency shifters and beam splitters." Nature 599, no. 7886 (2021): 587-593. DOI: 10.1038/s41586-021-03999-x0028-08361476-4687https://nrs.harvard.edu/URN-3:HUL.INSTREPOS:37377119Mian Zhang is the CEO of Hyperlight a startup compaynEfficient frequency shifting and beam splitting is important for a wide range of applications, including atomic physics1,2, microwave photonics3–6, optical communication7,8, and photonic quantum computing9–14. However, realizing gigahertz-scale frequency shifts with high efficiency, low loss, and tunability, in particular using a miniature and scalable device, is challenging since it requires efficient and controllable nonlinear processes. Existing approaches based on acousto-optics6,15–17, all-optical wave mixing10,13,18–22, and electro-optics23–27 are either limited to low efficiencies or frequencies, or are bulky. Furthermore, most approaches are not bi-directional, which renders them unsuitable for frequency beam splitters. Here we demonstrate electro-optic frequency shifters that are controlled using only continuous and single-tone microwaves. This is accomplished by engineering the density of states of, and coupling between, optical modes in ultra-low loss waveguides and resonators in lithium niobate nanophotonics28. Our devices, consisting of two coupled-ring-resonators, provide frequency shifts as high as 28 GHz with an ~90% on-chip conversion efficiency. Importantly, the devices can be reconfigured as tunable frequency-domain beam splitters. Using the device, we also demonstrate a non-blocking and efficient swap of information between two frequency channels. Finally, we propose and demonstrate a scheme for cascaded frequency shifting that allows shifts of ~120 GHz using a ~30 GHz continuous and single-tone microwave signal. Our devices could become building-blocks for future high-speed and large-scale classical information processors7,29 as well as emerging frequency-domain photonic quantum computers9,11,14.en-USMultidisciplinaryJournal Article2023-09-2710.1038/s41586-021-03999-x