Wavelength sensitivity of indium tin oxide on surface plasmon resonance angles

Authors: ANTONIO RUIZ, CARLOS VILLA ANGULO, IVAN OLAF HERNANDEZ-FUENTES

Abstract: Surface plasmon resonance (SPR) is a charge-density oscillation that occurs when a beam of p-polarized monochromatic light impinges with a greater angle than the critical angle in a dielectric-metal interface. Because of the high losses related to metals, the generated surface plasmon waves propagate with high attenuation in the visible and near-infrared spectral regions in most of the dielectric-metal interfaces. An alternative to reduce such losses is to use a transparent indium tin oxide (ITO) film. In this paper, we compared theoretical calculations and experimental measurements of the SPR angle $\theta_{SPR}$ on the interfaces of a borosilicate prism (Bp) and ITO, Bp-Ag, and Bp-Au. Three different wavelengths (405, 532, and 650 nm) were used to measure $\theta_{SPR}$ that covered almost all of the visual range spectrum. Both calculations and experimental data showed that SPR characteristics are strongly influenced by the metal's optical properties. The measured $\theta_{SPR}$ in the Bp-ITO interface is much smaller than the $\theta_{SPR}$ measured in the other two interfaces. Hence, ITO can be used in a similar way as Au and Ag in prism-metal interfaces, providing a cheaper and more versatile option to generate the SPR effect.

Keywords: Surface plasmon resonance, borosilicate prism, indium tin oxide, silver, gold

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