Active dielectric metasurface based on phase-change medium

• Published in: Laser & photonics reviews Vol. 10; no. 6; pp. 986 - 994
• Main Authors: Chu, Cheng Hung, Tseng, Ming Lun, Chen, Jie, Wu, Pin Chieh, Chen, Yi-Hao, Wang, Hsiang-Chu, Chen, Ting-Yu, Hsieh, Wen Ting, Wu, Hui Jun, Sun, Greg, Tsai, Din Ping
• Format: Journal Article
• Language: English
• Published: Weinheim Blackwell Publishing Ltd 01.11.2016; Wiley Subscription Services, Inc
• Subjects: Angle of reflection; beam steering; Computer memory; Computer simulation; Constituents; Fano resonances; Materials selection; Mathematical models; metamaterials; Phase transitions; phase-change material; Photonics; reconfigurable metasurface; Reflection; Rods
• ISSN: 1863-8880; 1863-8899
• DOI: 10.1002/lpor.201600106

We propose all‐dielectric metasurfaces that can be actively re‐configured using the phase‐change material Ge2Sb2Te5 (GST) alloy. With selectively controlled phase transitions on the composing GST elements, metasurfaces can be tailored to exhibit varied functionalities. Using phase‐change GST rod as the basic building block, we have modelled metamolecules with tunable optical response when phase change occurs on select constituent GST rods. Tunable gradient metasurfaces can be realized with variable supercell period consisting of different patterns of the GST rods in their amorphous and crystalline states. Simulation results indicate a range of functions can be delivered, including multilevel signal modulating, near‐field coupling of GST rods, and anomalous reflection angle controlling. This work opens up a new space in exploring active meta‐devices with broader applications that cannot be achieved in their passive counterparts with permanent properties once fabricated. The all‐dielectric reconfigurable metasurfaces based on switchable phase‐change material Ge2Sb2Te5 with functional diversity for light modulation are shown. The tunability of EIT resonance on phase‐change metamolecule and the steering of gradient metasurface are demonstrated by selectively modifying the phase of selected constituent Ge2Sb2Te5 rods.