A High‐Sensitivity Light‐Induced Thermoelastic Spectroscopy Sensor Based on Dual‐Path Synergistic Coupling Method

ABSTRACT This paper proposed a highly sensitive light‑induced thermoelastic spectroscopy (LITES) sensor based on the dual‑path synergistic coupling (DPSC) method for the first time. The technique utilized a three‑stage quartz tuning fork (QTF) synergistic architecture, establishing a signal enhancement mechanism in which acoustic and electrical paths operated in parallel. In this method, the thermoelastic signal generated by QTF1 under laser irradiation was processed through two distinct routes. One path underwent electrical filtering and amplification by a high‑Q QTF2, while the other drove the resonant QTF3 through near‑field acoustic coupling. The two processed signals were then coherently combined, enhancing the signal amplitude. The results demonstrate that, compared with the bare‐LITES sensor, the DPSC‐LITES sensor increases the signal amplitude and signal‑to‑noise ratio (SNR) by 321% and 166%, respectively.