Tapered photonic crystal fiber interferometer with enhanced sensitivity

We fabricate a miniature tapered photonic crystal fiber (PCF) interferometer with enhanced sensitivity by a new acid microdroplets etching method. This method, without elongating the PCF, moving and re-fixing the device during etching and measuring refractive index sensitivity, is very simple, cost-efficient and highly stable over time. We investigate the refractive index sensing properties with different PCF diameters both theoretically and experimentally. The size decreases and the sensitivity increases an order of magnitude after etching the PCF. If we can optimize the etching process, we can fabricate more uniformly and thinly tapered PCF interferometer with higher sensitivity (~ 100 times) theoretically in the future.