DATE2025.06.12 #Press Releases

Ultra-broadband full absorber with carbon-coated moth-eye structure

Disclaimer: machine translated by DeepL which may contain errors.

---Development of a Broadband Optical Absorber with Over 98% Absorption from 1 to 1200 THz Using a Carbon-Coated Moth-Eye Structure on Silicon---

Summary 

A research group led by Associate Professor Kuniaki Konishi at the Graduate School of Science, the University of Tokyo, in collaboration with the University of Eastern Finland and the State Research Institute Center for Physical Sciences and Technology (Lithuania), has succeeded in creating an artificial material that achieves over 98% absorption across an extremely wide frequency range (1–1200 THz) by coating a silicon-based moth-eye structure with a 100 nm-thick carbon film.
Materials that can efficiently absorb light or electromagnetic waves are indispensable in fields such as energy conversion, radiation control, and electromagnetic shielding. Professor Konishi’s lab has previously developed anti-reflective moth-eye structures in the terahertz region using laser processing.
In this study, by coating the surface of the moth-eye structure with a 100 nm-thick carbon layer, the team has demonstrated ultra-broadband perfect light absorption, spanning from terahertz to deep ultraviolet.

Materials that efficiently absorb light and electromagnetic waves are indispensable in diverse fields such as energy conversion, radiation control, and electromagnetic shielding. Konishi Laboratory has been developing non-reflective moth-eye structures in the terahertz range, which are fabricated by laser processing. In this study, in order to realize a broadband optical absorbing material in an artificial structure, the surface of the moth-eye structure was coated with a thin carbon material with a thickness of 100 nm, and it was found that the material exhibits ultra-broadband perfect optical absorption properties ranging from terahertz to deep UV (Figure 1). This achievement is expected to have various applications in energy conversion and control of infrared radiation, in addition to electromagnetic shielding materials used in the fields of telecommunications and radio astronomy.

Figure 1: Absorption spectrum of a moth-eye structure coated with a thin carbon film
0.Absorption properties in the range 5 THz - 1200 THz were measured using four different techniques (orange: terahertz time-domain spectroscopy, green and blue: Fourier transform infrared spectroscopy, purple: spectrophotometry). 98% or higher absorption was observed in all frequency regions above 1 THz.

Journals

Journal Title	Advanced Optical Materials
Title of Paper	Carbon-Coated Moth-Eye Structure : An Ultrabroadband THz-DUV near-Perfect Absorber
Author(s)	Yuki Hakamada, Maria Cojocari, Mizuho Matoba, Shotaro Kawano, Haruyuki Sakurai, Kuniaki Konishi*, Daniil Pashnev, Surya Revanth Ayyagari, Vytautas Janonis, Andrzej Urbanowicz, Saulius Tumėnas, Justinas Jorudas, Irmantas Kašalynas*, Janna Pennanen, Adigun Adigun Deborah Amos, Aleksandr Saushin, Georgy Fedorov*, Yuri Svirko, Polina Kuzhir
DOI Number	10.1002/adom.202500948