Integrated photonics on thin-film lithium niobate
Lithium niobate (LN), an outstanding and versatile material, has influenced our daily life for decades—from enabling high-speed optical communications that form the backbone of the Internet to realizing radio-frequency filtering used in our cell phones. This half-century-old material is currently embracing a revolution in thin-film LN integrated photonics. The successes of manufacturing wafer-scale, high-quality thin films of LN-on-insulator (LNOI) and breakthroughs in nanofabrication techniques have made high-performance integrated nanophotonic components possible. With rapid development in the past few years, some of these thin-film LN devices, such as optical modulators and nonlinear wavelength converters, have already outperformed their legacy counterparts realized in bulk LN crystals. Furthermore, the nanophotonic integration has enabled ultra-low-loss resonators in LN, which has unlocked many novel applications such as optical frequency combs and quantum transducers. In this review, we cover—from basic principles to the state of the art—the diverse aspects of integrated thin-film LN photonics, including the materials, basic passive components, and various active devices based on electro-optics, all-optical nonlinearities, and acousto-optics. We also identify challenges that this platform is currently facing and point out future opportunities. The field of integrated LNOI photonics is advancing rapidly and poised to make critical impacts on a broad range of applications in communication, signal processing, and quantum information.
© 2021 Optical Society of America. Received October 5, 2020; revised February 16, 2021; accepted February 22, 2021; published May 3, 2021 (Doc. ID 411024). We thank Smarak Maity, Prashanta Kharel, Cheng Wang, Yoshitomo Okawachi, Marc Jankowski, and David Barton for helpful discussion and critical reading of the paper. We acknowledge collaborations with Cheng Wang, Martin M. Fejer, Joseph Kahn, Alex Gaeta, Michal Lipson, Xi Chen, Peter Winzer, Nathalie Picque, Oliver King, Ronald Esman, Shanhui Fan, Keji Lai, Carsten Langrock, Brandon Buscaino, James Leatham, Kevin Luke, Lingyan He, and Tianhao Ren. We also acknowledge collaboration and support from NanoLN (Hui Hu) and Covesion (Corin Gawith). Relevant research conducted at Harvard is sponsored by NSF, ONR, AFOSR, DARPA, DOE, ARL, ARO, Raytheon, Nokia Bell Labs, Rockwell Collins, and Google; and device fabrication is performed at the Harvard University Center for Nanoscale Systems, a member of the National Nanotechnology Coordinated Infrastructure Network. D.Z. is supported by the Harvard Quantum Initiative (HQI) postdoctoral fellowship. N.S. acknowledges support by the Natural Sciences and Engineering Research Council of Canada (NSERC), the AQT Intelligent Quantum Networks and Technologies (INQNET) research program, the DOE/HEP QuantISED program grant, QCCFP (Quantum Communication Channels for Fundamental Physics), and NSF STC "Center for Integrated Quantum Materials." Finally, we thank everyone who contributed to the field of integrated thin-film lithium-niobate photonics, without whom this review would not have been possible. Funding: National Science Foundation; Harvard Quantum Initiative; Natural Sciences and Engineering Research Council of Canada; Office of Naval Research; Air Force Office of Scientific Research; Defense Advanced Research Projects Agency; U.S. Department of Energy; Army Research Laboratory; Army Research Office; Raytheon Company; Nokia Bell Labs; Rockwell Collins; Google; U.S. Department of Energy; Alliance for Quantum Technologies, California Institute of Technology (INQNET). Disclosures: MZ,CR: HyperLight Corporation (I,E,P); ML: HyperLight Corporation (F,I,C).
Accepted Version - 2102.11956.pdf