Chiral Coupling in T-shaped Gold Nanodimers

Strong optical activity in T-shaped metal nanodimers with a nanogap was shown through polarization-sensitive second-harmonic generation (SHG). Chirality in gold nanodimers was studied by circular-difference (CD) measurements, where the SHG efficiency of a sample is compared for left- and right-circular fundamental polarizations. A strong dependence of the SHG CD response on nanogap size that does not directly correlate with the dependence of the SHG intensity obtained was found.