Abstract
We study electric and magnetic hotspots in the gap between hollow InSb microspheres forming dimers and trimers. The outer radius, core volume fraction, distance, and temperature of the microspheres can be chosen to achieve field enhancement at a certain frequency corresponding to the transition between energy levels of a molecule placed in the gap. For example, utilizing 80 μm radius spheres at a gap of 2 μm held at a temperature of 295 K, allow electric field intensity enhancements of 10–2880 and magnetic field intensity enhancements of 3–61 in the frequency window 0.35–1.50 THz. The core volume fraction and the ambient temperature affect the enhancements, particularly in the frequency window 1.5–2 THz. Electric and magnetic hotspots are promising for THz absorption and circular dichroism spectroscopy.
Highlights
In the past two decades, the generation and detection of coherent terahertz (THz) radiation have attracted much attention[1,2]
Based on the abundance of biological chiral molecules, it is proposed that THz circular dichroism spectroscopy will be of use in searching for extraterrestrial life[9]
We assume that two identical hollow InSb microspheres are at positions r1 = (0, Rout + dp/2, hp) and r2 = (0, −Rout − dp/2, hp)
Summary
In the past two decades, the generation and detection of coherent terahertz (THz) radiation have attracted much attention[1,2]. For example in the case of 80 μm radius spheres of core fraction 0.8, the trimer better enhances the electric (magnetic) field in the frequency window 1.10–2 THz (1.44–2 THz). With spheres of outer radius (30, 50, 80) μm and core fraction (0.8, 0.8, all values of f), the maximum electric field enhancement (4.65, 3.63, 3.13) occurs at frequency νE =
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