Abstract-Subdiffraction focusing of total electric fields of terahertz wave

Mengyu Yang, Desheng Ruan, Lianghui Du, Chunyan Qin, Zeyu Li, Cuiping Lin, Gang Chen, Zhong Quan Wen,



https://www.sciencedirect.com/science/article/abs/pii/S0030401819309307

Terahertz lens is an essential component in terahertz application. We propose a focusing of total electric fields planar lens based on super-oscillation. This planar lens is designed for a wavelength ($\lambda$) of 118.$8\mathrm{\mu }\mathrm{m}$ with a radius of 160$\lambda$, a focal length of 210 $\lambda$ and a numerical aperture of 0.606. Our experiment demonstrates a subdiffraction and subwavelength focusing of total electric fields. The full width at half-maximum of the focal spot is 0.67 $\lambda$, which is smaller than the diffraction limit of 0.825$\lambda$. The results shows that it has powerful application for terahertz imaging, especially in the fields of biomedical science.