期刊
ADVANCED SCIENCE
卷 7, 期 14, 页码 -出版社
WILEY
DOI: 10.1002/advs.202000799
关键词
electromagnetically induced transparency; germanium; silicon; terahertz metamaterials; ultrafast photoswitching
资金
- National Natural Science Foundation (NSF) of China [11802339, 11805276, 61805282, 61801498, 11804387, 11902358]
- Scientific Researches Foundation of National University of Defense Technology [ZK16-03-59, ZK18-01-03, ZK18-03-36, ZK18-03-22]
- NSF of Hunan Province [2016JJ1021]
- Hunan Provincial Innovation Foundation for Postgraduate [CX2018B006]
- Open Research Fund of Hunan Provincial Key Laboratory of High Energy Technology [GNJGJS03]
- Opening Foundation of State Key Laboratory of Laser Interaction with Matter [SKLLIM1702]
- Youth Talent Lifting Project [17-JCJQ-QT-004]
Incorporating active materials into metamaterials is expected to yield exciting advancements in the unprecedented versatility of dynamically controlling optical properties, which sheds new light on the future optoelectronics. The exploration of emerging semiconductors into terahertz (THz) meta-atoms potentially allows achieving ultrafast nanodevices driven by various applications, such as biomedical sensing/imaging, ultrawide-band communications and security scanners. However, ultrafast optical switching of THz radiation is currently limited to a single level of tuning speed, which is a main hurdle to achieve multifunctionalities. Here, a hybrid metadevice which can realize the pump-wavelength controlled ultrafast switching response by the functionalization of double photoactive layers is demonstrated experimentally. A whole cycle of electromagnetically induced transparency switching with a half-recovery state changes from 0.78 ns to 8.8 ps as pump wavelength varies from near infrared to near ultraviolet regions. The observed pump-color selective switching speed changing from nanosecond scale to picosecond scale is ascribed to the wavelength-dependent penetration length of Ge and the contrasting defect states between noncrystalline Ge and epitaxial Si layers. It is believed that the schemes regarding pump-color controllable ultrafast switching behavior introduced here can inspire more innovations across the field of ultrafast photonics and can boost the reconfigurable metamaterial applications.
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