Bias-Free Functional Terahertz Photoconductive Emitter

The ability to sculpt terahertz (THz) wavefronts in the generation process is crucial for communication and imaging applications. However, related devices, known as functional THz emitters with wavefront modulation capabilities, remain scarce. Here, we propose an approach for directly generating specific THz wavefronts based on a bias-free photoconductive THz emitter using bimetal antennas. The emitted THz radiation arises from the drift current driven by the lateral Schottky (LS) barrier and the lateral photo-Dember (LPD) effect. Meanwhile, by precisely engineering the geometric parameters and orientation of the antenna, we achieve continuous control over both the amplitude and phase of the emitted THz waves, thus, allowing the flexible control of the THz wavefront. Our method enables broadband THz wavefront control with a simple design, low fabrication cost, and suitability for large-area processing.