High-performance surface plasmon resonance-based photonic crystal fiber sensor with four open surface rings

In this paper, a photonic crystal fiber sensor is proposed with four open-ring channels that enhances sensor performance with increased coupling features. By detecting the optical spectrum of leakage from the fiber core to the channels, the sensitivity of the sensor can be assessed. Gold is used as the plasmonic material coated on titanium oxide film which is employed as a substrate layer to increase adhesion and sensor performance. The influence of structural parameters on the sensor performance is investigated by the finite-difference time-domain method. Sensor response is investigated for a wide refractive index range of 1.34-1.44. As a result of applying these four analyte channels, maximum wavelength and amplitude sensitivity of 25,600 nm/RIU and 7367 RIU-1 and figure of merit (FOM) of 547 RIU-1, where RIU is the refractive index unit, were calculated. In addition to high sensitivity, the proper FOM value of this sensor is an important feature which makes it suitable for identifying chemicals and biomolecules.