Surface Plasmon Resonance (SPR) based PCF Sensor Design

Abstract

In recent years, many new designs with great sensitivity have been introduced in the field of SPR based PCF sensors. Designing is challenging since most designs exhibit high sensitivity and high loss or have low sensitivity and low loss. In order to achieve high sensitivity, designs become complex. Our work is focused on the PCF-SPR sensors that are fabricate friendly and have high sensitivity with low loss. Our designs feature circular air holes within the PCF and the outer surface is coated with Au along with a layer of TiO2. Au work as a plasmonic material and TiO2 layer increases the adhesivity between gold and fiber. All the analysis of the parameters of the sensors are done by implementing the finite element method (FEM) of COMSOL multiphysics 5.3a. Our first sensor exhibits maximum amplitude sensitivity of 4233 RIU-1 whereas maximum confinement loss is 6.22 dB/cm. The same sensor has a sensor resolution of 2.36×10-6. In our 2nd design, first gold is used as plasmonic material for which we get maximum AS of 5336 RIU-1 and maximum wavelength sensitivity of 40500nm/RIU for a RI range of 1.32-1.43. Later AZO is replaced by gold which has given more sharp peak and increased the RI range to 1.19-1.42. The FOM for Gold was 744 RIU-1 and for AZO 440 RIU-1. This sensor is also used to detect temperature where maximum sensitivity is 1.05 nm/oC with a resolution of 0.095oC. In addition to all these, we introduced a novel detection parameter called ‘Double Step Verification’ for detecting temperature which takes the help of the change in double peak shift of resonance wavelength to determine the temperature. As a result of all these diverse functionality, our sensor can be concluded as a major developer in the detection of a wide range of analytes in bio and chemical fields as well as a step forward in the field of temperature sensing.