Numerical Demonstration of the Blueshift of the Light Absorption Wavelength for a Layered Microsphere: Effects of Shell Thickness on the Blueshift

Abstract

The present study is an extension of former research where a double-layer (TiO2/SiO2) microsphere was irradiated by using monochromatic unpolarized plane light. The effect of the shell thickness on the blueshift is primarily investigated in this paper. For a common size (500 nm radius) of a core-shell sphere, various core sizes were chosen to make the shell layer have different thicknesses. With five pre-determined shell thicknesses, we could find the wavelength positions where light absorption should take place. We also demonstrate that the locations of the light, intensity fluctuations, i.e., the wavelengths of light absorption, move to smaller values (the blue side). Specifically: numerical calculations show that the absorption wavelengths changed from 580 nm to 463 nm as the shell layer thickness was changed from 250 nm to 50 nm. This may be the cause of the light. absorption at the smaller wavelength, which is called the blueshift. The blueshift demonstrated numerically in this investigation has been already seen in many experiments done by other groups.