Broadband laser-processed terahertz moth-eye antireflection structure with a controlled lattice type

Fabrication of antireflection moth-eye structures on the surface of optical materials is an important method for suppressing Fresnel reflection in the terahertz frequency range. However, the antireflection bandwidth of such moth-eye structures is currently limited by the aspect ratio of fabricable structures. In this study, we explore the possibility of broadening the antireflection bandwidth of laser-processed moth-eye structures by altering the lattice type of fabricated moth-eye structures among hexagonal, square, and honeycomb configurations. According to the results of experiments and simulations, a hexagonal lattice configuration results in a 15% higher upper limit of the antireflection frequency than the square lattice, without compromising the processing efficiency. This study contributes to the advancement of terahertz technology by optimizing antireflection structures for broader bandwidths, such as astronomical observation and wireless communications, where the widest possible bandwidth is required.