Modified bow-tie antenna array with efficient electric near-field enhancement for terahertz band

Abstract

Antenna arrays can induce strong electric near-field enhancement to improve the performance of biological imaging resolution, macromolecule detection sensitivity, and sensing accuracy. However, the use of antenna arrays to regulate both the electric near-field enhancement factor and area has rarely been reported. In this paper, a novel modified bow-tie (MBT) antenna array is proposed for better near-field enhancement performance in terahertz (THz) regime. Using commercially available high frequency structure simulator (HFSS), the dimensions of the MBT antenna array, including gap width, arm length, array period, and substrate thickness, are optimized to improve electric near-field enhancement performance in terms of higher factor, larger area, more controllable peak frequency, and wider 1-dB bandwidth. The as-optimized MBT and bow-tie (BT) THz antenna arrays are fabricated on quartz substrate via lithography and lift-off process. The normalized transmittances of the MBT and BT antenna arrays are characterized by THz time-domain spectroscopy (THz-TDS) and compared with the corresponding simulated near-field enhancement factor and normalized transmittance. The results indicate that the MBT antenna array outperforms the BT antenna array with a three-fold increase in near-field enhancement area and a 66.7% wider 1-dB bandwidth, and therefore can be used to enhance detection sensitivity and sensing accuracy in weak terahertz environment.