Simultaneous Transmission and Reflection Terahertz Homodyne Imaging System with Integrated Resonant C-Shaped Metalenses

Abstract

This work introduces an enhanced terahertz (THz) imaging system based on a homodyne detection scheme with integrated resonant C-shaped complementary split-ring resonator metalenses, specifically designed for 253 GHz frequency to address the imaging challenges posed by low-absorbing dielectric materials. The system provides significant improvements over conventional direct imaging techniques, offering simultaneous imaging in both transmission and reflection geometries, thus enabling a comprehensive evaluation of the relative absorption properties. The integration of complementary split-ring resonator metalenses allows for subwavelength resolution, enhancing image contrast and delivering over twice the dynamic range of 68 dB for homodyne and 30 dB for direct imaging. The performance of the proposed imaging system based on a homodyne detection scheme is compared with the hyperspectral THz time-domain spectroscopy, and its superiority over the conventional direct THz imaging technique is revealed.