Resonant Optical Modes in Periodic Nanostructures

The resonant nanostructures are significant for enhancing the electromagnetic field density in a nanoscale region, suitable for many novel nanophotonic applications. This review article provides an insight into various optical resonance phenomena associated with resonating structures. We initiated our discussion with photonic resonating structures and extended to the excitation mechanism of various plasmonic modes and their applications. Further, we have extended the discussion on the hybrid photonic-plasmonic mode generation through the interaction of photonic-plasmonic resonances, which can substantially concentrate the electromagnetic field with remarkable quality factor. We have also briefly reviewed the newly emerging class of resonating structures known as the metasurfaces originated through the scattering of the electromagnetic wave through dynamic charge-current oscillation, enabling wavefront modulation, polarization tuning, and nonlinear harmonic generation. Then, we extended our review very briefly to the non-radiating resonant modes evolved by suppressing the coupling of resonant state with the radiation channels resulting in the formation of the anapole and bound state in the continuum. The anapole state has been realized in a structure supporting electric and magnetic resonance, mainly in a metasurface, whereas the BIC state has been experimentally realized in a comprehensive range of photonic, plasmonic, metasurface, and different hybrid material-based structures.