Highly sensitive plasmonic sensor based on eccentric-core photonic crystal fibers

To further reduce the fabrication difficulty of optical fiber sensors and improve the sensing performance, this study introduced the surface plasmon resonance (SPR) effect into optical fiber sensing technology and designed an eccentric-core photonic crystal fiber (EC-PCF). We investigated the characteristics of the two fundamental modes in the fiber core and the surface plasmon polariton (SPP) modes on the surface of the gold film. We also investigated the influence of the structural parameters, such as gold film coating area and thickness, air hole diameter, and eccentricity, on the confinement loss and achieved a refractive index (RI) sensitivity of 31.25 & mu;m RIU-1 in the RI range of 1.29-1.43, corresponding to a figure of merit (FOM) of 521.6 per RIU. When the resolution of the optical spectrum analyzer was 0.1 nm, the EC-PCF could achieve a refractive index resolution of 3.2 x 10(-6) RIU. Moreover, we performed tests with two typical sensing types, one in which the sensor was directly in contact with adulterated gasoline to achieve kerosene-concentration detection, and another in which the sensor was coated with a layer of polydimethylsiloxane (PDMS), whose RI is sensitive to the temperature field, to achieve temperature sensing. The EC-PCF demonstrated excellent sensing performance and offers obvious manufacturing advantages, providing a new and easily fabricated structural design idea for optical fiber sensing.

Automated summary

To improve the fabrication difficulty and sensing performance of optical fiber sensors, this study introduced surface plasmon resonance (SPR) effect and designed an eccentric-core photonic crystal fiber (EC-PCF). The study investigated the characteristics of different modes and the influence of structural parameters on the sensing performance, achieving a high refractive index sensitivity and resolution. Tests with different sensing types demonstrated the excellent performance of EC-PCF, providing a new and easily fabricated design idea for optical fiber sensing.