Broadband plasmonic nanoantenna with an adjustable spectral response.

Six-particle and eight-particle common-gap plasmonic nanoantennas are utilized to obtain a broadband spectral response when illuminated with circular and elliptical polarization. Due to the insensitivity of dipole antennas to circular polarization, the resonant structures are brought together around the common-gap to expand the spectrum of the whole system. Their ability to focus light at different frequencies is demonstrated. The spectral response is manipulated by geometrical parameters and the strength of the spectral peaks is tailored through the ellipticity of the elliptically polarized light.