High-Sensitivity and High-Precision RI Sensing Using THz-Comb-Based Frequency Multiplication and Dual-Comb Active-Dummy Temperature Compensation

This paper presents a novel optical-comb-based refractive index sensor that simultaneously achieves high-sensitivity and high-precision by combining THz-comb-based frequency multiplication with active-dummy temperature compensation in a dual-comb configuration. In this approach, a little RI-induced shift of the comb mode spacing ( frep) is frequency-multiplied via THz frequency comb, while the dual-comb scheme compensates for temperature drift in frep. Experimental results demonstrate a 3100-fold improvement in RI sensitivity and a 10-fold enhancement in measurement precision.