Surface-enhanced circular dichroism spectroscopy on periodic dual nanostructures

9 pags., 4 figs.Increasing the sensitivity of chiral spectroscopic techniques such as circular dichroism (CD) spectroscopy is a current aspiration in the research field of nanophotonics. Enhancing CD spectroscopy depends on two complementary requirements: the enhancement of the electromagnetic fields perceived by the molecules under study and the conservation of the helicity of those fields, guaranteed by duality symmetry. In this work, we introduce a systematic method to design nanostructured dual periodic photonic systems capable of enhancing molecular CD spectroscopy resonantly. As an illustration, we engineer a dual 1D silicon nanoparticle array and show that its collective optical modes can be efficiently employed to resonantly enhance by 2 orders of magnitude the local density of optical chirality and, thus, the CD signal obtained from a given molecular sample on its vicinity.J.L.A., J.J.S., and A.G.E. acknowledge the PID2019-109905GAC22 Project of the Spanish Ministerio de Ciencia, Innovacion y Universidades (MICIU). D.R.A. acknowledges partial financial support from Grant No. MELODIA PGC2018- 095777-B-C21 of MICIU and from the Ministerio de Educación, Cultura y Deporte through the FPU Ph.D. Fellowship FPU15/03566. A.N. acknowledges finacial support from the MICIU through the FPI Ph.D. Fellowship BES-2017- 080073. G.M.T. acknowledges the FIS2017-87363-P Project of the Spanish MINECO. A.G.E. and J.A. acknowledge the FIS2016-80174-P Project of the Spanish MINECO. A.G.E. received funding from the Gipuzkoako Foru Aldundia OF23/ 2019 (ES) Project, “Fellows Gipuzkoa” Fellowship through FEDER “Una Manera de hacer Europa”, and by Eusko Jaurlaritza Grant Numbers KK-2017/00089, IT1164-19, PI2016-41, and KK-2019/00101