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Proceedings Paper

Broadband and wide angle light absorption for an aluminum nanorod array in a prism-coupling system
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Paper Abstract

Traditional optical thin films exhibit low absorption when light is incident obliquely because the optical path decreases with increasing angle of incidence [1]. A thin film absorber is also a challenge to perform high absorption at oblique incidence. Under the condition of total reflection, a thin metal film with thickness around 40nm in a Kretschmann configuration (prism / metal film / air) enables to absorb light at an extremely small angle range by exciting surface plasmon at the interface of metal/air [2]. In this work, a metamaterial thin film composed of aluminum nanorods is fabricated and used to absorb light in high efficiency. An aluminum nanorod array (Al NRA) deposited obliquely is arranged in a prism-coupling system to observed the reflection under the condition of total reflection of the system: BK7 prism/ Al NRA/ Air. The Al NRA is 184nm thick and tilted at an angle of 35° with respect to the surface normal. The deposition plane defined by the directions of rod and surface normal is orientated at angles of φ=0° and φ=180° with respect to the plane of incidence to measure the reflectance versus incident angles from 45° to 70° and wavelengths from 400nm to 700nm. The definition of the NRAs orientation is shown in Fig. 3. When the deposition plane is the same with the plane of incidence, the reflectance spectra indicate that the Al NRA exhibits strong absorptance over 80% at angles of incidence from 45° to 55° for both p-polarization and s-polarization. The enhanced p-polarized absorptance is extended from 45° to 70°. At φ=90°, the absorptance is weaker at angles of incidence from 55° to 70° compared with other two cases measured at φ=0° and φ=180°°.

Paper Details

Date Published: 19 September 2013
PDF: 6 pages
Proc. SPIE 8818, Nanostructured Thin Films VI, 88180V (19 September 2013); doi: 10.1117/12.2023980
Show Author Affiliations
Yi-Jun Jen, National Taipei Univ. of Technology (Taiwan)
Jia-Wei Dai, National Taipei Univ. of Technology (Taiwan)
Jung-Hui Chao, National Taipei Univ. of Technology (Taiwan)

Published in SPIE Proceedings Vol. 8818:
Nanostructured Thin Films VI
Tom G. Mackay; Akhlesh Lakhtakia; Yi-Jun Jen; Motofumi Suzuki, Editor(s)

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