Design and fabrication of novel broadband near-perfect black absorber having microstructured surface

Amemiya, Kuniaki*; Koshikawa, Hiroshi; Yamaki, Tetsuya; Maekawa, Yasunari; Shitomi, Hiroshi*; Kinoshita, Kenichi*; Numata, Takayuki*; Tanabe, Minoru*; Fukuda, Daiji*

The novel broadband near-perfect black absorber for an absolute radiometer has been developed. Microstructured surface having high-aspect-ratio conical pores was fabricated by swift heavy ion beam irradiation and following etching process; subsequently, the surface was coated with black layer. Incident light which enters into the surface microstructure experiences multiple reflections which enhance optical absorption; therefore, the net reflectance decreases much less than 1% with sufficient pit aspect ratio and absorption layer thickness, which can be designed by finite differential time domain (FDTD) method calculation. Furthermore, a prototype of the novel black absorber also exhibited good mechanical durability. This newly developed black material is also expected to have potential application in various fields of optical energy management such as stray light elimination.