Prism dispersion effects in near‐guided‐wave surface plasmon resonance sensors

Abstract

Refractive index dispersion causes the light line to curve. As a result it is shown that when the prism is dispersive, an additional dip in the spectral response of Surface Plasmon Resonance (SPR) sensors is observed in the Kretschmann-Raether (KR) configuration. Since the new dip evolves in the infrared (IR) region, it exhibits a high sensitivity to the analyte refractive index (RI) changes and the mode penetrates deeper into the analyte. Adding a thin dielectric layer with high refractive index on top of the metallic layer enables to control the dip location and strength. The two dips shift in opposite directions as the analyte RI changes and therefore when the spectral difference is considered as the measurand, higher RI sensitivity is obtained. The dispersion relation of two thin films bounded by two semi-infinite media is derived when the prism dispersion is considered.

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

“…The guided modes are spectrally narrow and well defined and can be continuously tuned in the NIR region by controlling the SiO 2 layer thickness. In the SPR case, on the other hand, we observe two dips that are generated due to the prism dispersion as was previously shown by Shalabney and Abdulhalim [25]. The dispersion of the prism in this spectral region leads to bending in the dispersion branch of the SPR mode as shown in Figure 4(c), and thereby two possible resonances are observed as indicated by the arrows.…”

Broadband surface plasmon wave excitation using dispersion engineering

“…To the right of the broadband surface plasmon (for larger incident angles), the surface plasmon dispersion curve crosses the light line in two points. This corresponds to two narrow band surface plasmons [16].…”

“…Equation 2 indicates that the prism dispersion, ε p (ω), partially compensates for dispersion of the dielectric permittivities of the metal and of the analyte, ε m (ω) and ε d (ω). Prism dispersion has been used in the past for dispersion compensation in the context of lasers [25,26], for excitation of several narrow-band surface plasmons at the same incident angle [16], and for the measurement of the plasma edge in semiconductors [12]. Fig.…”

Surface plasmon excitation using a Fourier-transform infrared spectrometer: Live cell and bacteria sensing

“…where n prism is the refractive index of the prism, θ is the angle of incidence, several resonant wavelengths. 24,25 The reflectivity at the resonance achieves its minimum since the energy of the incident wave is converted into the surface plasmon wave instead of going to the reflected wave. The efficiency of this conversion is determined by the thickness of the conducting layer which is usually optimized to achieve a deep reflectivity minimum at a certain resonance wavelength, λ SPR.…”