Highly sensitive refractometer with photonic crystal fiber long-period grating

摘要

We present highly sensitive refractometers based on a long-period grating ina large mode area PCF. The maximum sensitivity is 1500 nm/RIU at a refractiveindex of 1.33, the highest reported for any fiber grating. The minimaldetectable index change is $2\times 10^{-5}$. The high sensitivity is obtainedby infiltrating the sample into the holes of the photonic crystal fiber to givea strong interaction between the sample and the probing field.