In-line photonic crystal fiber optofluidic refractometer

We report the fabrication and characterization of an in-line photonic crystal fiber optofluidic refractometer assisted by a C-shaped fiber. The C-shaped fiber spliced between the PCF and the SMF enables simultaneous in-line optical signal delivery and analyte fluid feeding. Using an arc discharge technique, we achieve selective exploitation of only the central two voids of the PCF for microfluidic sensing. Based on a Sagnac interferometer, a highly sensitive refractometer with sensitivity of 8699 nm/RIU and detection limit of 10–⁶ for RI around 1.333 was achieved experimentally, which agrees well with the theoretical value of 8675 nm/RIU.