Qu Che, Ma Shaojie, Hao Jiaming, Qiu Meng, Li Xin, Xiao Shiyi, Miao Ziqi, Dai Ning, He Qiong, Sun Shulin, Zhou Lei
State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education) and Physics Department, Fudan University, Shanghai 200433, People's Republic of China.
National Laboratory for Infrared Physics, Shanghai Institute of Technical Physics, Chinese Academy of Science, Shanghai 200083, People's Republic of China.
Phys Rev Lett. 2015 Dec 4;115(23):235503. doi: 10.1103/PhysRevLett.115.235503. Epub 2015 Dec 1.
Metasurfaces in a metal-insulator-metal configuration have been widely used in photonics, with applications ranging from perfect absorption to phase modulation, but why and when such structures can realize what functionalities are not yet fully understood. Here, we establish a complete phase diagram in which the optical properties of such systems are fully controlled by two simple parameters (i.e., the intrinsic and radiation losses), which are, in turn, dictated by the geometrical or material properties of the underlying structures. Such a phase diagram can greatly facilitate the design of appropriate metasurfaces with tailored functionalities demonstrated by our experiments and simulations in the terahertz regime. In particular, our experiments show that, through appropriate structural or material tuning, the device can be switched across the phase boundaries yielding dramatic changes in optical responses. Our discoveries lay a solid basis for realizing functional and tunable photonic devices with such structures.
金属-绝缘体-金属结构的超表面已在光子学中得到广泛应用，其应用范围从完美吸收到相位调制，但此类结构为何以及何时能够实现何种功能尚未得到充分理解。在此，我们建立了一个完整的相图，其中此类系统的光学特性由两个简单参数（即本征损耗和辐射损耗）完全控制，而这两个参数又由底层结构的几何或材料特性决定。这样的相图能够极大地促进具有定制功能的合适超表面的设计，这在我们太赫兹波段的实验和模拟中得到了证明。特别是，我们的实验表明，通过适当的结构或材料调整，该器件可以在相界之间切换，从而在光学响应上产生显著变化。我们的发现为实现具有此类结构的功能性和可调谐光子器件奠定了坚实基础。
