Investigations of refractive index sensing with a photonic crystal fiber interferometer

We report a photonic crystal fiber (PCF) interferometer was realized by fusion splicing a short section of PCF between two standard single mode fibers (Corning SMF-28) using a Fitel-S175 splicer. The fully collapsed air holes of the PCF at the spice regions allow the coupling of PCF core and cladding modes. The transmission spectrum exhibits sinusoidal interference pattern which shifts differently when the cladding/core surface of the PCF is immersed with different RI of the surrounding medium. The results for different concentrations of sucrose solution show that a resolution of 1.21×10^-4 -4.65×10^-4 RIU is achieved for refractive indices in the range of 1.333 to 1.403, suggesting that the PCF interferometer are attractive for chemical, biological, and biochemical sensing with aqueous solutions.