Sensitivity enhancement in photonic crystal fiber interferometer

In this paper, we demonstrated two methods to enhance refractive index (RI) and temperature sensitivity of a photonic crystal fiber (PCF) in-line modal interferometer built via fusion splicing, respectively. First we fabricated a tapered PCF interferometer by an etching method with acid microdroplets. The RI sensitivity greatly increases (5 times) and the size decreases after tapering the PCF, while the temperature sensitivity does not change a lot. Then we obtained another PCF interferometer by inserting a short isopropanol-filled PCF between two single mode fibers (SMFs). The temperature sensitivity increases over an order of magnitude compared with the previous non-polarimetric sensors based on air-filled PCF interferometers.