Abstract

A high-refractive-index dielectric particle with the ability of supporting both electric and magnetic resonances, operating at 1–2 terahertz, is proposed. It is shown that the suggested omega-shaped nanoparticle is able to control the resonance frequencies independently by changing geometrical dimension. It is also demonstrated numerically that an asymmetric omega particle shows a tunable radiation pattern, depending on the incident frequency. The radiation beam can steer in the range of $\pm 30°$. The omega particle shows a directive radiation pattern with small back radiation, due to the constructive interference of the induced electric and magnetic moments. Therefore, the application of the proposed antenna in directivity enhancement is considered. Then, in order to achieve high directivity, omega particles are arranged in an array. Their employment for directivity enhancement has led to the maximum directivity of 11.8 dB. Side-lobe level has the minimum amount of $-18.3\mathrm{dB}$, and total size of the structure is $400\mathrm{\mu m}\times 400\mathrm{\mu m}\cong 2.6\lambda \times 2.6\lambda$ in the $x\text{-}y$ plane, while it does not exceed a quarter of a wavelength in height.

© 2018 Optical Society of America

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