Terahertz spatial light modulation by phase change metasurface with pixel-wise switchable control

Recently, the versatility of metasurfaces for pixel-wise wave regulation prompts emerging metadevices with spatially variant controllability, especially the spatial light modulator (SLM), with reliable prospects for applications in many scenarios. Somehow, the modulation depth and operating bandwidth remain elusive technical challenges, restricting the application scenarios and performance. In this paper, we propose a metasurface-based scheme for broadband terahertz (THz) SLM with large modulation depth as well as spatially varying programmable control. The phase change chalcogenide of Ge2Sb2Te5 (GST) is integrated into meta-annulus units for electrically switchable and independent control of each pixel. For proof-of-concept experiments, a THz SLM composed of an array of 5 × 5 addressable pixels with electrically switchable transmittance is demonstrated. Finally, the feasibility of our scheme is confirmed by simulations and experiments with an average modulation depth (MD) of 87.8% in the range of 0.36 THz to 0.57 THz, potentially providing a remarkable feature for broadband applications in THz imaging, sensing and communication, etc.