Ultra-broadband terahertz radar imaging with a 4-in. spintronic strong-field emitter.

Terahertz (THz) radar offers significant advantages, notably high-frequency and strong penetration ability, making it highly promising for applications in aerospace, non-destructive testing, and other imaging scenarios. However, existing THz radar imaging technologies face challenges in large-scale target detection due to the complexity and high costs of the system, which limits their development and commercial application. Here we establish a radar system based on a one-dimensional photonic crystal structure-enhanced 4-inch spintronic strong-field THz emitter and obtain THz radar signals and imaging with a signal-to-noise ratio of ∼58 dB and a bandwidth exceeding 5 THz. Through the precise design of the emitter structure, we ensure not only the generation of a high-quality uniform plane wave when the THz beam diameter reaches 4 in. but also the applicability of the THz field strength for radar imaging measurements within a 4-in. field of view area. The approach provides a promising platform for ultra-broadband, high-resolution, near-monostatic THz radar imaging, with broad potential applications in aerospace engineering, stealth testing, THz 3D reconstruction, and THz tomography.