Optimization of Cladding Diameter for Refractive Index Sensing in Tilted Fiber Bragg Gratings
Korganbayev S. Sypabekova M. Amantayeva A. González-Vila Á. Caucheteur C. Saccomandi P. Tosi D.
March-2 2022MDPI
Sensors
2022#22Issue 6
This work presents an experimental investigation of the effect of chemical etching on the refractive index (RI) sensitivity of tilted fiber Bragg gratings (TFBGs). Hydrofluoric acid (HF) was used stepwise in order to reduce the optical fiber diameter from 125 µm to 13 µm. After each etching step, TFBGs were calibrated using two ranges of RI solutions: the first one with high RI variation (from 1.33679 RIU to 1.37078 RIU) and the second with low RI variation (from 1.34722 RIU to 1.34873 RIU). RI sensitivity was analyzed in terms of wavelength shift and intensity change of the grating resonances. The highest amplitude sensitivities obtained are 1008 dB/RIU for the high RI range and 8160 dB/RIU for the low RI range, corresponding to the unetched TFBG. The highest wavelength sensitivities are 38.8 nm/RIU for a fiber diameter of 100 µm for the high RI range, and 156 nm/RIU for a diameter of 40 µm for the small RI range. In addition, the effect of the etching process on the spectral intensity of the cladding modes, their wavelength separation and sensor linearity (R2) were studied as well. As a result, an optimization of the etching process is provided, so that the best trade-off between sensitivity, intensity level, and fiber thickness can be obtained.
Chemical etching , Etching optimization , Optical fiber sensors , Refractive index sensing , Tilted fiber Bragg grating
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Politecnico di Milano, Milan, 20156, Italy
School of Medicine, Nazarbayev University, Nur-Sultan, 020000, Kazakhstan
School of Engineering and Digital Sciences, Nazarabayev University, Nur-Sultan, 010000, Kazakhstan
Baylor Research and Innovative Collaborative, Baylor University, Waco, 76704, TX, United States
Electromagnetism and Telecommunication Department, University of Mons, Mons, 7000, Belgium
Biosensors and Bioinstrumentation Laboratory—National Laboratory Astana, Nur-Sultan, 010000, Kazakhstan
Politecnico di Milano
School of Medicine
School of Engineering and Digital Sciences
Baylor Research and Innovative Collaborative
Electromagnetism and Telecommunication Department
Biosensors and Bioinstrumentation Laboratory—National Laboratory Astana
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