Abstract
We theoretically and numerically investigated the local field enhancement factor (<I>LFEF</I>), absorption coefficient, refractive index, and group velocity of spherical core-shell nanocomposites (<i>NCs</i>) using the quasi-static approach. By solving Laplace’s equations, we derived expressions for the enhancement factor, polarizability, absorption coefficient, refractive index, and group velocity for each core-shell <i>NCs</i>. Our findings show that the LFEF, absorption coefficient, and group velocity of spherical core-shell <i>NCs</i> exhibit two peaks, while the real part of the refractive index shows four distinct peaks. Additionally, the core-shell nanocomposites demonstrate greater tunability and a higher intensity of the enhancement factor when the host matrix is changed from <i>CdSe</i> to <i>SiO<sub>3</sub></i>. The study further reveals that, for spherical nanocomposites, the first two peaks of the enhancement factor and extinction cross-sections occur at the same frequencies. Moreover, all extinction cross-section peaks are lowest when the dielectric function of the host matrix is <i>SiO<sub>3</sub></i>, whereas the peaks are highest for <i>CdSe</i>. The variation in peak values, despite having the same number of peaks for different shapes, indicates that the shape of the core-shell <i>NCs</i> significantly influences the intensity, number, and positions of the peaks in the enhancement factor and optical cross-sections. Such nanocomposites hold potential for applications in optical sensing, biosensing, as well as in photonic and electronic devices.
Published Version
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