We report on the optical activity of a trimer of plasmonic nanorods in terms of circular dichroism. The results are investigated both theoretically and numerically. Remarkably, efficient tuning the inter-particle distances manipulates the intensity, bandwidth, and the symmetry of the circular dichroism spectrum. Well organized nanoparticles, increase the bandwidth as well as the maximum of the of circular dichroism spectrum which is a desired objective in the field of chiroptical spectroscopy methods and proposing novel nanophotonic devices. It is found that at the appropriate inter-particle distance, the nanostructure shows a dual band circular dichroism spectrum. Theses outstanding properties are due to the plasmonic hybridized modes. Actually, in phase and out of phase plasmonic modes are one of the key factors responsible for inducing chirality in metal nanostructures. The theoretical results are obtained using the theory of coupled dipole approximation. It is shown that the theoretical results are well supported by the numerical results.
