T-ray Photoconductive Antenna Design for Biomedical Imaging Applications

Photoconductive antennas are promising sources of terahertz (THz) radiation, which is frequently used to investigate and analyze biological organisms. These compact antennas make it possible to generate ultra-broadband pulses and continuously tunable THz transmissions at room temperature without the need for high-power laser sources. Here, a high efficiency spiral THz photoconductive antenna (PCA) is proposed. The design consists of a gallium arsenide (GaAs) substrate and a silicon (Si) hyper hemispherical lens. The proposed design has a radiation efficiency of up to 92.4% between 2.5 and 3.4 THz, with a directivity up to 17.6 dBi. With several current PCA designs as references, comparisons and analyses are made, indicating that the proposed work shows higher efficiency and radiation directivity at a wider band. The design of electrodes and hyper hemispherical lens are demonstrated in the paper. Simulations of contrast designs are shown as well, illustrating a 25%-40% efficiency and 12.8 dB gain increase by this design. Due to its performance and small structure, this antenna is ideal for T-ray medical imaging.