We propose a stop-band filter in infrared region using a periodically chirped subwavelength structure. The structure is made of a stack of metal and dielectric pattern made on a thick metal layer that is deposited a PMMA substrate. It is found that an appropriately designed microstructure of metal-insulator-metal patches can generate a wideband infrared absorption, resulting in an infrared stop-band filter. Different width of metal-insulator-metal resonator arranged in one unit cell generate trough in the reflection spectrum at different wavelengths. The full width at half magnitude (FWHM) of the stop-band filter can thus be adjusted by tuning the width of the resonators. The larger the range of the resonator width, the wider the bandwidth will be. Under the condition of subwavelength dimension of the structure compared with the working wavelength, it is found that a FWHM of 4μm at central wavelength of ~9μm and a high absorption efficiency of up to 80% can be achieved. The proposed structure provides a novel method in the design of wideband efficient plasmonic absorbers in infrared or THz spectral regions with simultaneously wide bandwidth and high efficiency of absorption.

Date Published: 23 August 2013
PDF: 7 pages
Proc. SPIE 8911, International Symposium on Photoelectronic Detection and Imaging 2013: Micro/Nano Optical Imaging Technologies and Applications, 891112 (23 August 2013); doi: 10.1117/12.2035422

Published in SPIE Proceedings Vol. 8911:
International Symposium on Photoelectronic Detection and Imaging 2013: Micro/Nano Optical Imaging Technologies and Applications
Min Gu; Xiaocong Yuan; Min Qiu, Editor(s)