Surface Plasmon Resonance Sensor Based on Modified <inline-formula> <tex-math notation="LaTeX">$D$ </tex-math> </inline-formula>-Shaped Photonic Crystal Fiber for Wider Range of Refractive Index Detection

A wider range of refractive index (RI) detecting <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$ </tex-math></inline-formula> -shaped photonic crystal fiber (PCF)-based surface plasmon resonance (SPR) sensor is proposed in this paper for the RI detection of analyte ranging from 1.18 to 1.36. To make the proposed sensor practically implementable, analyte sensing layer and chemically stable gold (Au) as a plasmonic material layer for SPR are placed outside the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$ </tex-math></inline-formula> -shaped PCF structure as a part of simple detection technique. Using the finite-element method with a circular perfectly matched boundary layer, it is shown through simulations that the proposed <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$D$ </tex-math></inline-formula> -shaped PCF-based SPR sensor offers maximum wavelength interrogation sensitivity of 20 000 nm/RIU…