High Sensitive Refractive Index Sensor Based on Cladding Etched Photonic Crystal Fiber Mach-Zehnder Interferometer
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A high sensitive refractive index sensor based on the cladding etched photonic crystal fiber (PCF) Mach-Zehnder interferometer (MZI) is proposed, which is spliced a section of photonic crystal fiber between two single modes fibers (SMFs).The interference fringe of the MZI shifts with the variation of the ambient refractive index (RI). It is found that the RI sensitivity slightly decrease with an increase in the interference length. The sensitivities of MZI with 35 mm PCF, 40 mm PCF, and 45 mm PCF are 106.19 nm/RIU, 93.33 nm/RIU, and 73.64 nm/RIU, respectively, in the range of 1.333 to 1.381. After etched, the RI sensitivity of the MZI could be improved obviously. The RI sensitivities of the MZI with 35 mm PCF are up to 211.53 nm/RIU and 359.37 nm/RIU when the cladding diameter decreases to 112 μm and 91 μm, respectively. Moreover, the sensor is insensitive to temperature, and the measured sensitivity is only 9.21 pm/°C with the range from 20°C to 500°C. In addition, the sensor has advantage of simple fabrication, low cost, and high RI sensitivity.
KeywordsRefractive index sensor Mach-Zehnder interferometer photonic crystal fiber hydrofluoric acid
This research work is supported by the National Natural Science Foundation of China (NSFC) (Grant Nos. 51475482, 51875584, 51875585, and 51475481), the National Key R&D Program of China (Grant Nos. 2017YFB1104800 and 2018YFB1107803), and the Fundamental Research Funds for the Central Universities of Central South University.
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