  Circular dichroism (CD) is absorption difference of right-hand and left-hand
circularly polarized light by components. CD spectroscopy technique is an
important tool for detecting molecular chirality, but the molecular circular
dichroism (MCD) is weak and always appears in the ultraviolet (UV) region that
is more noisy than visual range (VR). Induced circular dichroism (ICD) arisen
from near-field interaction of plasmonic nanostructures and chiral molecules
enhances the detection limit of molecular chirality and usually appears in VR.
In this study, quadrilateral arranged nanoholes (QAN) are proposed for
enhancing the MCD. The maximum enhancement achieved by the structure is about
200 folds of the MCD. Furthermore, we explained the mechanism of ICD which is
generated by symmetry breaking of electric field QAN by molecular dipole. We
investigated the effect of surface plasmon resonance (SPR) mode on ICD through
analyzing the electric dipole (ED) and magnetic dipole (MD) resonance modes.
ICD was found to get enhanced as a result of overlapping of ED and MD resonance
around QAN. Besides this investigation, we probed the effects of thickness of
structure, length of holes and length of periods on the MCD enhancement
