Enhanced terahertz vibrational absorption spectroscopy using integrated high-Q resonator

• Zhibo Hou, liao chen, Rongwu liu, Chi Zhang, Xiaojun Wu, and Xinliang Zhang
• received 02/29/2024; accepted 05/07/2024; posted 05/08/2024; Doc. ID 522518
• Abstract: The terahertz absorption spectrum, is a powerful method to identify substances. The improvement focuses on sensitivity and recovery ability. In this study, we demonstrate an enhanced terahertz vibrational absorption spectroscopy based on an on-chip terahertz whispering gallery mode resonator (THz-WGMR). THz-WGMR with high Q can store energy and enhance the interaction between the terahertz waves and the target substances to capture the unique absorption fingerprint information. Therefore, it possesses significant sensitivity to identify trace amounts of substances. As a proof of concept, the lactose powder and glucose powder are applied to demonstrate the effectiveness of our approach in recovering fingerprint absorption spectroscopy. Compared with a straight waveguide, the high sensitivity of our work is illustrated. The change of the transmissivity caused by the lactose reaches 7.8 dB around 532 GHz for THz-WGMR while only 1.4 dB for straight waveguide, demonstrating the state-of-the-art sensing performance in fingerprint absorption recovery. We believe the proposed scheme will promote the terahertz identification of tiny fingerprint substances.