Wide-angle spectral imaging using a Fabry-Pérot interferometer

In this work, a refractive index sensor setup based on a biconically tapered fiber (BTF) concatenated to an intrinsic all-fiber micro Fabry-Perot interferometer (MFPI) is presented. Here, the power of the MFPI spectral fringes decreases as the refractive index interacts with the evanescent field of the BTF segment. Furthermore, it is demonstrated that the RI sensitivity can be enhanced by bending the BTF segment. Finally, it is shown that by using this sensing arrangement, at ∼1.53 μm wavelength, it is possible to detect refractive index changes within the measurement range of 1.3 to 1.7 RIU, with a sensitivity of 39.92 dB/RIU and a RI resolution of 2.5 ⋅ 10 −3 RIU with a curvature of C = 18.02 m −1 .