Ultra-Sensitive Refractive Index Sensor With Slightly Tapered Photonic Crystal Fiber

We fabricate a miniature ultra-sensitive refractive index sensor based on a tapered photonic crystal fiber (PCF) modal interferometer. The PCF is slightly tapered and a little elongated to keep the size compact. The total length is ~ 2 cm, and the potential sensitivity is more than 1600 nm/RIU (refractive index unit), which is nearly eight times as high as that of an untapered PCF interferometer.