Enhanced terahertz radiation from nanorod array targets irradiated by ultraintense laser pulses

Ultraintense laser interactions with a metal foil offer an emerging approach toward the generation of intense terahertz (THz) radiation, and how to improve the THz generation efficiency remains an open question. Here, we report the enhanced generation of THz radiation from ultraintense laser-irradiated nanostructured targets where metallic nanorod arrays are fabricated on the front surface of foil targets. The influences of nanorod lengths on the THz radiation emitted from the foil rear surface are investigated experimentally. Compared to the case of flat foil targets, a maximum enhancement in the THz pulse energy by a factor of 2.3 is observed by varying the nanorod length, and the THz peak emission direction moves toward the target surface with longer nanorods. Measurements of escaping fast electrons imply that the boosted THz yield is attributed to the enhanced laser absorption, and thus, the substantial increase in the fast-electron number. Particle-in-cell simulations reproduce well the experimental results. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution-NonCommercial 4.0International (CC BY-NC) license