Refractive index sensing characteristics of microdroplet-etched fiber Fabry-Perot resonator

Abstract

Abstract: In order to improve the measurement precision and sensitivity of refractive index, an asymmetric cross-sectional microfiber Fabry-Perot resonator is realized using an HF-acid droplet etching technique. The fabricated structure is featured with small size, low loss, large birefringence and high Q value. The guided modes along the orthogonal polarizations present different refractive index (RI) responses due to its dissimilar evanescent field fraction outside of the fiber. Our measured RI sensitivities are 133.8 nm/RI-unit and 117.1 nm/RI-unit for the modes along the fast axis and the slow axis, respectively. Simultaneously, the temperature responsivity is 11.99 pm/℃ for the two polarization modes. Thus the temperature cross sensitivity can be eliminated by monitoring the peak difference between the two polarizations, since they have the similar temperature coefficient but different RI responses. From experimental results, the sensitivity of the FP resonator becomes large when the diameter of cavity decreases and the ratio between the corrosion length and the cavity length increases.

Key words: fiber Fabry-Perot resonator

CLC Number:

TN253

References

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