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The metamaterial is an arrangement of artificial structural elements designed to achieve advantageous and unusual electromagnetic properties. In the unit cell level, metamaterials are composed of an array of small structured elements called split ring resonators (SRRs). Recently, a lot of emphases has been given to the realization of terahertz metamaterials owing to its significance in the construction of terahertz photonic components. In this context, near-field coupling in terahertz metamaterials is extremely crucial. The short-range coupling in metamaterials occurs via the electric and magnetic fields due to the close proximity of the neighboring resonators. The electric field mainly couples through the gaps of SRRs, while the magnetic field couples through the circumference. In this work, we experimentally investigate near-field gap to gap capacitive coupling between a pair of single split gap ring resonators (SRRs) in a terahertz metamaterial. This has been achieved by manipulating the near field electric interactions via changing one resonator split gap with respect to the other resonator split gap for several inter resonator separations. Introducing asymmetry by changing the split gap in one resonator with respect to the other resonator, results in the split in the fundamental resonance mode when operated in the strong near-field coupled regime. The split occurs because of the strong near field capacitive/electric interactions between the resonators. We have further calculated Q factor for the lower and higher resonance modes for different inter resonator separations. The modulation of resonances in capacitive coupled planar terahertz metamaterial systems studied through this work has great potential in manipulating and controlling electromagnetic waves which can ultimately result in novel applications for terahertz frequency domain.
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