Terahertz single-pixel near-field imaging based on active tunable subwavelength metallic grating
Xingye Yang, Zhen Tian, Xieyu Chen, Mengyuan Hu, Zhihao Yi, Chunmei Ouyang, Jianqiang Gu, Jiaguang Han, Weili Zhang
Abstract
Terahertz (THz) single-pixel near-field imaging, producing images by introducing a scene with a series of spatially resolved subwavelength patterns while recording the correlated intensity on a single-element detector, is a promising technology for imaging applications. Spatial light modulator (SLM) is one of the key devices in THz single-pixel near-field imaging. Combined with a Digital Micromirror Device to shape the optical pump beam, a photo-induced tunable high-efficiency, ultra-thin, and fast THz SLM is presented by integrating designed subwavelength metallic grating into silicon on sapphire. In the experiments, the SLM is demonstrated with an over 60% THz peak amplitude modulation depth and broad bandwidth under a relative low pump fluence (80 μJ/cm2). The measurements, simulations, and calculations agree well with each other. Meanwhile, sub-nanosecond decay time extracted by fitting the |ΔT| curve suggests a fast response device. A two-dimensional grating is also explored, and the polarization-independent feature makes it easier to use. Finally, an imaging demonstration is conducted to verify the usability of the designed device. These results demonstrate the feasibility of realizing super-resolution and even real-time imaging simultaneously.