RT Journal Article SR Electronic T1 Nanoscale optical pulse limiter enabled by refractory metallic quantum wells JF Science Advances JO Sci Adv FD American Association for the Advancement of Science SP eaay3456 DO 10.1126/sciadv.aay3456 VO 6 IS 20 A1 Qian, Haoliang A1 Li, Shilong A1 Li, Yingmin A1 Chen, Ching-Fu A1 Chen, Wenfan A1 Bopp, Steven Edward A1 Lee, Yeon-Ui A1 Xiong, Wei A1 Liu, Zhaowei YR 2020 UL http://advances.sciencemag.org/content/6/20/eaay3456.abstract AB The past several decades have witnessed rapid development of high-intensity, ultrashort pulse lasers, enabling deeper laboratory investigation of nonlinear optics, plasma physics, and quantum science and technology than previously possible. Naturally, with their increasing use, the risk of accidental damage to optical detection systems rises commensurately. Thus, various optical limiting mechanisms and devices have been proposed. However, restricted by the weak optical nonlinearity of natural materials, state-of-the-art optical limiters rely on bulk liquid or solid media, operating in the transmission mode. Device miniaturization becomes complicated with these designs while maintaining superior integrability and controllability. Here, we demonstrate a reflection-mode pulse limiter (sub–100 nm) using nanoscale refractory films made of Al2O3/TiN/Al2O3 metallic quantum wells (MQWs), which provide large and ultrafast Kerr-type optical nonlinearities due to the quantum size effect of the MQW. Functional multilayers consisting of these MQWs could find important applications in nanophotonics, nonlinear optics, and meta-optics.