Polarization-resolved dual-mode near-field terahertz single-pixel imaging.

We present a polarization-resolved dual-mode near-field terahertz single-pixel imaging (THz-SPI) scheme that enables polarization-insensitive isotropic sub-wavelength imaging. A [110]-cut ZnTe crystal enables synchronous acquisition of orthogonally polarized THz near-field images. To resolve the longstanding polarization-dependent resolution anisotropy in conventional THz near-field imaging, we develop a fusion model based on signal-to-noise ratio (SNR) and total variation (TV) criteria, yielding an optimized weight coefficient of r = 0.52. The fused image achieves an SNR of 22.97 (∼1.5-fold enhancement over single-polarization images) and eliminates resolution anisotropy, enabling high-fidelity polarization-resolved imaging of microscale structures. This work provides a robust framework for polarization-resolved THz detection and isotropic sub-wavelength imaging, broadening the applicability of near-field THz-SPI for versatile terahertz metrology.