Metal nanorod array coupling property in Kretschmann system
碩士 === 國立臺北科技大學 === 光電工程系研究所 === 101 === Traditional optical thin films exhibit low absorption when light is incident obliquely because the optical path decreases with increasing angle of incidence. A thin light absorber is also a challenge to perform high absorption at oblique incidence. Under...
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| Format: | Others |
| Language: | zh-TW |
| Published: |
2013
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| Online Access: | http://ndltd.ncl.edu.tw/handle/7d75a7 |
| Summary: | 碩士 === 國立臺北科技大學 === 光電工程系研究所 === 101 === Traditional optical thin films exhibit low absorption when light is incident obliquely because the optical path decreases with increasing angle of incidence. A thin light 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 200nm 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. In this work, a metamaerial thin film composed of metal nanorods is fabricated and used to absorb light in high efficiency.
A metal nanorod array(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/ metal NRA/ Air. The metal NRA is around 200nm 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 =0˚ and =180˚ with respect to the plane of incidence to measure the reflectance versus incident angles from 40˚ to 70˚ and wavelengths from 400nm to 700nm.
When the deposition plane is the same with the plane of incidece, the reflectance spectra indicate that the metal NRA exhibits strong absorptance over 80% at angles of incidence from 40˚ to 55˚ for both p-polarization and s-polarization. The enhanced p-polarized absorbtance is extended from 40˚ to 70˚.
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