Reconfigurable terahertz spatial differentiation via incident angle tuned beam shifts on a Bi2Te3 platform
Optical spatial differentiation offers an ultrafast, low-power route to edge detection by directly processing the optical field and can address the inherent diffraction-limited blurring of terahertz (THz) imaging. However, existing THz edge detection schemes face persistent bottlenecks. Metasurfaces and diffractive devices are fixed in function once fabricated, whereas tunable approaches demand stringent angular alignment that limits practical deployment. Here, we theoretically demonstrate a reconfigurable THz spatial differentiator built on the topological insulator Bi2Te3. The device achieves single-parameter mode reconfigurability, enabling seamless switching among one-dimensional (1D) x-direction, 1D y-direction, and isotropic two-dimensional edge enhancement solely by varying the incident angle at a fixed Fermi energy. It also offers favorable parameter robustness, including a broad angular tolerance for 1D x-direction mode and insensitivity to external magnetic fields. Transfer function analysis and edge detection simulations validate the device performance, providing a robust platform for dynamic THz optical computing and high-contrast edge imaging.