Turn a Highly-Reflective Metal into
 an Omnidirectional Broadband Absorber by Coating a Purely-Dielectric Thin Layer of Grating

doi:10.2528/PIER12102808

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Progress In Electromagnetics Research	ISSN: 1070-4698, E-ISSN: 1559-8985

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TURN A HIGHLY-REFLECTIVE METAL INTO AN OMNIDIRECTIONAL BROADBAND ABSORBER BY COATING A PURELY-DIELECTRIC THIN LAYER OF GRATING

By F. Zhang, L. Yang, Y. Jin, and S. He

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Abstract:
We show that a metal can be turned into a broadband and omnidirectional absorber by coating a purely-dielectric thin layer of grating. An optimal design for such an absorber is proposed by putting a dielectric slot waveguide grating (SWG) on the metallic substrate. The SWG consists of two germanium nanowires (Ge NWs) separated by a sub-100 nm slot in each period. Average absorption reaches 90% when the incident angle varies between 0° and 80° over a broad wavelength range from 300 nm to 1400 nm. Multiple optical mechanisms/effects, namely, diffraction, waveguiding in the high-index Ge NWs and low-index air slot, Fabry-Perot resonances as well as surface plasmon polaritons (SPPs), are identified to govern the absorption characteristics of the present absorber. The designed absorber with such a dielectric grating is easier to fabricate as compared with other absorbers with metallic structures, and has potential applications in e.g. solar cells and photodetectors.

Citation:
F. Zhang, L. Yang, Y. Jin, and S. He, "Turn a Highly-Reflective Metal into an Omnidirectional Broadband Absorber by Coating a Purely-Dielectric Thin Layer of Grating," Progress In Electromagnetics Research, Vol. 134, 95-109, 2013.
doi:10.2528/PIER12102808
http://www.jpier.org/PIER/pier.php?paper=12102808

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