Numerical simulation study of terahertz photoconductive antenna structure optimization and anti-reflection film design

Terahertz technology has significant potential in medical imaging, non-destructive testing, and communication by virtue of its high penetrability, fingerprint spectral properties, and low photon energy. However, the existing radiation sources suffer from the bottleneck of low power and insufficient efficiency. Photoconductive antenna (PCA), as a mainstream device, is limited by the low optical current density, slow response speed, and light absorption loss of the traditional electrode structure. In this paper, we propose a synergistic optimization scheme of zigzag electrode (ZE PCA) and HfO 2 /Si multilayer antireflection film: the zigzag electrode enhances the edge electric field distribution, resulting in a peak photocurrent up to 33.2 μA (2.3 times that of the conventional electrode) and a shortening of response time to 0.22 ps; the multilayer antireflection film suppresses the reflection to <5% and improves the optical absorption efficiency to 92%. The photocurrent grows linearly with laser power (10-30 mW) and bias voltage (10-30 V), but is limited by carrier complexation and space charge effects. This study provides theoretical and technological support for the miniaturised design of high-power, fast-response terahertz devices.