Anti-reflection structure fabrication is a laser patterning technique used to reduce Fresnel reflections.
Anti-reflection (AR) coatings aimed at reducing Fresnel reflection losses have come into demand in the terahertz (THz) region. Implementation of such a coating is a difficult task, partially because the broad spectrum of the THz signal. Femtosecond lasers enable moth-eye AR structures capable of suppressing reflection losses in the range of 0.3 to 2.5 THz for high-resistivity silicon, resulting in a maximum transmission of 91%. Pyramid-like structures, with a height of about 100 µm, are created on the silicon, which is one of the most valuable materials for making optical components such as lenses, windows, and beam splitters, due to its high transparency in the THz region.
Periodic surface functional group density on graphene via laser-induced substrate patterning at Si/SiO2 interface
K. A. Drogowska‑Horna, I. Mirza, A. Rodriguez, P. Kovaříček, J. Sládek, T. J. Y. Derrien, M. Gedvilas, G. Račiukaitis, O. Frank, N. M. Bulgakova et al., Nano Research 9 (13), 2332-2339 (2020).
Terahertz broadband anti-reflection moth-eye structures fabricated by femtosecond laser processing
H. Sakurai, N. Nemoto, K. Konishi, R. Takaku, Y. Sakurai, N. Katayama, T. Matsumura, J. Yumoto, and M. Kuwata‑Gonokami, OSA Continuum 9 (2), 2764 (2019).