Broadband Terahertz Liquid Crystal Spatial Light Modulators for Multispectral Single-Pixel Imaging and Beam Scanning

Liquid crystal spatial light modulators (LC-SLMs) serve as core components in signal processing and display. However, their research and application in the terahertz band are constrained by three key limitations: low modulation depth, narrow operating bandwidth, and limited spatial resolution. In this study, we demonstrate an LC-SLM that simultaneously mitigates the aforementioned challenges while alleviating their mutual trade-offs. By leveraging polarization conversion within an anisotropic Fabry–Perot cavity constructed by LC metasurfaces, we validate amplitude modulation in transmission mode with a depth exceeding 75% across the frequency range of 0.2–1 THz, excluding only two discrete frequency points. The fabricated 40 × 40 pixel LC-SLM is successfully implemented as a programmable spatial mask for two key THz applications: multispectral single-pixel imaging and beam scanning. When integrated with terahertz time-domain spectroscopy, this system enables the high-fidelity reconstruction of both spatial and spectral information without mechanical movement. Our results open new avenues for advancing compact, low-cost, and efficient components to drive progress in THz imaging and communication systems.