Highly sensitive refractive index sensing based on PCF modal interferometer

Abstract A high sensitive optical fiber refractive index (RI) sensor based on Mach-Zehnder interferometer (MZI) is proposed. The sensor consists of single mode fiber-multimode fiber-photonic crystal fiber-single mode fiber (SMPS) structure using fusion technology. The experimental results have shown that the RI sensitivity of the SMPS structure is as high as 342.78 nm/RIU in the range of 1.3330~1.3775. Meanwhile, the effects of different length of PCF on the RI are also investigated. It was found that the shorter the length of PCF, the higher the sensitivity. In addition, a temperature sensitivity of 16.37 pm/℃ for the sensor is achieved. The sensor has advantages of high fringe visibility over 20 dB and simple fabrication, which has displayed great potential in the field of RI measurement.