Plasmon-Waveguide Resonances with Enhanced Figure of Merit and Their Potential for Anisotropic Biosensing in the Near Infrared Region

The TM and TE guided modes in the coupled plasmon-waveguide resonance configuration are investigated in the spectral domain. Here we use the modes dispersion to study their capability for sensing in the near infrared region. It is shown that the spectral widths of the guided modes are, at least, one order of magnitude smaller than the conventional surface plasmon resonance counterpart. The enhanced sensitivity and figure of merit of the guided modes reveal their potential for sensing in the spectral interrogation method where the traditional configurations are inherently limited. Moreover, the high resolution associated with the narrow resonances and the polarization dependence make these modes very promising for anisotropic biosensing in the spectral interrogation approach. The extremely high figure of merit, large penetration depth, and propagation distance in the near infrared region open the possibility of combining the plasmon-waveguide configuration with absorption spectroscopy techniques for molecular recognition.