Enhanced THz emission in a few-element 1D photoconductive antenna array

Photoconductive antennas (PCAs) have become privileged THz emitters due to the broadband spectrum, reliability, ease in fabrication, and flexibility in design. However, commonly used single-element PCA-emitters suffer from low conversion effciency that lies below 10 ⁻⁴ . In this paper, we re- port on a relatively simple and high-effcient 1D array PCA THz emitter with a judiciously-designed topology comprising of only a few dipole-type PCAs. When accounting an important trade-off in the array’s period, which simul- taneously impacts the laser pump effciency and redistributes power between the main and side lobes of the THz beam, the 1D array of only 7 PCAs ensures an 11-fold enhancement in the conversion effciency (by power, over the single-element PCA) in the frequency range of 0.3–3.5 THz exceeding 4.3 × 10 ⁻⁴ . Although the proposed 1D array PCA-emitter does not provide absorption of all laser pump power, the spatial reconstruction of its THz radi- ation pattern, thanks to the optimized design, provides a significant increase in conversion effciency. Moreover, the array conceptualization is technologi- cally reliable, and is much easier and miniaturized compared to conventional large-area and large-aperture PCA-emitters. The results of our findings are important for the further design and scaling of the PCA technology, aimed at meeting the demands of vigorously-explored THz spectroscopy, imaging, and exposure technologies.