Wednesday, 4 July 2012

Simple fabrication of an antireflective hemispherical surface structure using a self-assembly method for the terahertz frequency range

Dae-Seon Kim,  Dong-Ju Kim,  Dong-Hyun Kim,  Sehyun Hwang,  and Jae-Hyung Jang

OPTICS LETTERS / Vol. 37, No. 13 / July 1, 2012

School of Information and Communications, Gwangju Institute of Science and Technology, 1 Oryongdong, Buk-gu, Gwangju 500-712, South Korea Research Institute for Solar and Sustainable Energies, Gwangju Institute of Science and Technology, 1 Oryongdong, Buk-gu, Gwangju 500-712, South Korea, Department of Nanobio Materials and Electronics, World-Class University (WCU), Gwangju Institute of Science and Technology, 1 Oryongdong, Buk-gu, Gwangju 500-712, South Korea


A hemispherical surface structure was fabricated on a sapphire substrate by utilizing a self-assembly and spincoating process for a terahertz (THz) antireflection coating. The self-assembled glass spheres and spin-coated material led to a gradual change in the effective refractive index. The aspect ratio of the hemispherical surface structure was controlled easily by adjusting the thickness of the B-staged bisbenzocyclobutene used as a coating. The reflectance of the fabricated hemispherical surface structure, having a period of 140 μm, exhibited low reflectance and low Fabry–Perot resonance in a THz spectral range from 0.1 to 1.9 THz.

THz Pulsed Imaging and Spectroscopy

........The reflectance values of the sapphire substrate covered with the hemispherical surface structure were measured at a THz spectral range from 0.1 and 1.9 THz using a THz time domain spectroscopy system (TPS Spectra 3000TeraView)....................

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