Photonic Crystal Fiber-Based Surface Plasmon Resonance Sensor for Sensing Broad Range of Refractive Indices

Abstract

A twin core photonic crystal fiber-based surface plasmon resonance sensor has been designed in this work to detect a wide range of refractive indices with high sensitivity. The dual core fiber is polished on both sides and the metal layer is deposited on the polished surfaces as the plasmonic materials. Two microchannels are employed on each side of the fiber and thus the sensor forms four separate plasmonic layers on the external surface of the fiber to achieve a wide detection range. Plasmonic material silver is used here due to its availability and low cost. A thin layer of (TiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ) is used on top to prevent oxidation of silver. The proposed design is easy to fabricate and exhibits a good fabrication tolerance. The sensing application is also convenient as the analyte is placed outside the fiber. The analyte refractive index detection range of this sensor is found 1.23 – 1.44. The maximum spectral sensitivity of the sensor is 28200 nm/RIU and the corresponding resolution is 3.55 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−6</sup> RIU. The maximum amplitude sensitivity of the sensor is 286 RIU <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> . Due to its high sensitivity and wide detection range this sensor can be used to detect various low refractive index (1.23 – 1.29) chemicals (like halogenated anesthetic agents, refrigerants, different type of aerogels) to various bio materials (biological tissues, cancerous cells, hemoglobin) which has refractive indices usually in the range of 1.3 – 1.39, to various high index (1.4 – 1.44) analytes (like high concentration of electrolytes, proteins).