Broad-spectrum chiral optical response in achiral structures patterned from silver nanoparticles by plasmon-assisted two-photon direct laser lithography

We present an approach to produce plasmonic lithographic patterns with an extended circular dichroism response from the ultraviolet to the near infrared. We analyzed the optical chirality changes of the functionalized Ag nanospheres at every stage: from the chiral ligands to the patterned structures. The molecular chirality from the ligands is wavelength shifted and extended from the ultraviolet to visible after functionalization of the synthesized Ag nanoparticles in solution. New red shifted plasmon peaks appear in assembled metallic nanoparticles. Here we show that predefined optical properties of individual particles are also extended. Therefore, once the patterns are fabricated the optical activity is preserved and extended to the near infrared via induced collective plasmon modes.