molecules Review Advances in Photonic Devices Based on Optical Phase-Change Materials Xiaoxiao Wang 1, Huixin Qi 1, Xiaoyong Hu 1,2,3,*, Zixuan Yu 1, Shaoqi Ding 1, Zhuochen Du 1 and Qihuang Gong 1,2,3 1 Collaborative Innovation Center of Quantum Matter & Frontiers Science Center for Nano-Optoelectronics, State Key Laboratory for Mesoscopic Physics & Department of Physics, Beijing Academy of Quantum Information Sciences, Peking University, Beijing 100871, China;
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[email protected] (Q.G.) 2 Peking University Yangtze Delta Institute of Optoelectronics, Nantong 226010, China 3 Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China * Correspondence:
[email protected] Abstract: Phase-change materials (PCMs) are important photonic materials that have the advantages of a rapid and reversible phase change, a great difference in the optical properties between the crystalline and amorphous states, scalability, and nonvolatility. With the constant development in the PCM platform and integration of multiple material platforms, more and more reconfigurable photonic devices and their dynamic regulation have been theoretically proposed and experimentally demonstrated, showing the great potential of PCMs in integrated photonic chips. Here, we review the recent developments in PCMs and discuss their potential for photonic devices. A universal overview of the mechanism of the phase transition and models of PCMs is presented. PCMs have injected new life into on-chip photonic integrated circuits, which generally contain an optical switch, Citation: Wang, X.; Qi, H.; Hu, X.; an optical logical gate, and an optical modulator.