Hollow-core photonic crystal fiber refractive index sensor based on modal interference

Abstract

A refractive index sensor based modal interference in hollow core photonic crystal fiber (HCPCF) is proposed and demonstrated. The sensor is realized by splicing both ends of a HCPCF section to single mode fiber (SMF). At both splicing points, the HCPCF air holes are fully collapsed by the arc discharge. The collapsed regions excite and recombine core and cladding modes which formed modal interference for sensing purpose. The HCPCF sensor is tested in sugar solution and the response is measured from the wavelength shift in the interference spectra. The achieved sensitivity and resolution are 36.184 nm/RIU and 5.53-10-4 RIU, respectively, in refractive index range between 1.3330 and 1.3775. Result also shows that the sensor has a small temperature sensitivity of 19 pm/°C in the range of 35.5°C to 60.5 °C. The propos sensor potentially can be applied in biomedical, biological and chemical applications.