Photoactive Polymer‐Silicon Heterostructures for Terahertz Spatial Light Modulation and Video‐Rate Single‐Pixel Compressive Imaging

Abstract Terahertz (THz) waves, known for their low photon energy and unique spectral fingerprints, have broad applications in non‐destructive testing, biomedicine, and other fields. However, traditional THz imaging techniques are constrained by their long wavelength and slow imaging speeds due to raster scanning. Single‐pixel imaging offers a high‐throughput, high‐resolution alternative, yet the performance of THz spatial light modulators (SLMs) remains limited by the trade‐off between modulation depth and rate. Here, a polymer‐silicon heterostructure is proposed as a THz SLM using continuous‐wave (CW) optical illumination. The organic‐semiconductor interface promotes photo‐generated carrier accumulation, while the thickness of the silicon substrate influences the whole effective carrier lifetime. The design enables a THz SLM with both high modulation depth and fast modulation rate, ideal for THz single‐pixel imaging. A video‐rate single‐pixel super‐resolution imaging is demonstrated with a CW THz source. The dependence of imaging quality on the pump power and the switch rate of digital micromirror devices is investigated, which demonstrates that the imaging speed and imaging contrast are not limited by the carrier lifetime of silicon, rather than other hardware devices. In addition, the water content in a micro‐fluidic chip is tracked, highlighting the potential in bioanalysis and biomedical applications.