[10p-A11-1~12] 4.3 Laser sources and Laser applications

15:00 〜 15:15英語発表

[10p-A11-4] High-Stability Differential Refractive-Index Sensing Using a Single-Cavity Bidirectional Dual-Comb

〇(D)Masayuki Higaki¹, Yoshiaki Nakajima², Shuji Taue³, Eiji Hase¹, Yu Tokizane¹, Takeshi Yasui¹ (1.pLED, Tokushima University, 2.Toho University, 3.Kochi University of Technology)

キーワード：

Optical frequency comb、Refractive index sensing、Dual comb

We demonstrate high-stability differential refractive-index sensing using a single-cavity bidirectional dual-comb fiber laser with an intracavity multimode-interference fiber sensor. Two optical combs propagating in the clockwise and counterclockwise directions share the same sensor and cavity, enabling strong common-mode suppression of temperature-induced drift. Refractive-index changes in the sample are converted into optical spectral changes by the intracavity sensor and are read out as shifts in the repetition frequency through cavity dispersion. The differential repetition frequency, Δf_rep = f_rep,CW − f_rep,CCW, was used as the sensing signal. Experiments using ethanol–water solutions showed a linear response with a sensitivity of 737 Hz/RIU, R² = 0.993, and a resolution of 1.32 × 10⁻⁴ RIU.