Terahertz spectroscopy with compact apochromatic metasurface optics

Terahertz (THz) spectroscopy holds significant importance owing to the abundance of molecular and atomic fingerprint lines within this frequency range, enabling impactful applications in materials science, biology, and astronomy. Building on recent advancements in metasurface technology, we have developed a THz spectrometer that integrates a phase grating with two transmissive metasurfaces on a single platform. By mitigating chromatic dispersion and angular response limitations, the system incorporates a parallel focusing plane, simplifying integration with detector arrays, enhancing robustness, and reducing the requirement for incident light. Operating within the 1.23–1.43 THz range, the spectrometer achieves a theoretical resolution of 21 GHz, with a frequency resolution of 63 (f/Δf). This compact terahertz spectrometer offers scalable solutions for hyperspectral imaging and THz astronomical observation, demonstrating the transformative potential of metasurface technology for miniaturizing high-performance THz spectroscopy systems.