Theoretical Investigation on Coupled Plasmon Waveguide Resonance in Real and Complex Domain for High Precision Nanoplasmonic Sensing

Numerical investigations on modified multilayer coupled plasmonic structure, termed as coupled plasmon waveguide resonance (CPWR) structure, have been presented in real as well as complex plane domain. Coupling of waveguide resonance and plasmonic resonance results in dual resonance. Reflectance, field enhancement, and phase-dependent resonant behavior have been analyzed in angular interrogation for three different metal layers in order to optimize the structure with proper choice of metal layers. The resonance parameters have also been theoretically investigated in differential angular regime for better comparison of the shape of different resonance curves. Complex amplitude reflection and transmission co-efficients are analyzed with circular graphical plots in the complex plane. Simultaneous observations of the real and imaginary parts as well as amplitude and phase of the reflection and transmission co-efficients have been demonstrated. Different conventional optical polymers have been considered as waveguide layer materials and their respective real and complex plane analyses demonstrate the comparison for the proper choice of the waveguide layer. Moreover, the resonance parameters and the differential plots in real as well as complex plane for coarse and precise measurement have also been investigated for nanoplasmonic sensing applications to provide improved resolution.