A spectrally selective gap surface-plasmon-based nanoantenna emitter compatible with multiple thermal infrared applications
Ataollah Kalantari Osgouei, Amir Ghobadi, Bahram Khalichi, Ekmel Özbay
Abstract
Abstract Wavelength-selective nanoantenna emitters have attracted considerable attention due to their widespread applications ranging from thermal radiation management to thermophotovoltaics. In this paper, we design a wavelength-selective nanoantenna emitter based on the excitation of gap-surface plasmon modes using a metal–insulator–metal configuration (silicon dioxide (SiO 2 ) sandwiched between silver (Ag) layers) for satisfying multiple infrared applications. The proposed design, which is called design I, realizes triple narrowband perfect absorptions at the resonance wavelengths of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>1524</mml:mn> <mml:mrow> <mml:mtext>nm</mml:mtext> </mml:mrow> </mml:math> , <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>2279</mml:mn> <mml:mrow> <mml:mtext>nm</mml:mtext> </mml:mrow> </mml:math> , and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>6000</mml:mn> <mml:mrow> <mml:mtext>nm</mml:mtext> </mml:mrow> </mml:math> , which perfectly match the atmospheric absorption bands while maintaining relatively low emissivity in the atmospheric transparency windows of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>3</mml:mn> <mml:mo>−</mml:mo> <mml:mn>5</mml:mn> <mml:mi>μ</mml:mi> <mml:mrow> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>8</mml:mn> <mml:mo>−</mml:mo> <mml:mn>12</mml:mn> <mml:mi>μ</mml:mi> <mml:mrow> <mml:mtext>m</mml:mtext> </mml:mrow> </mml:math> . Later, the functionality of design I is extended, which is called design II, to include a broadband absorption at the near-infrared region to minimize the solar irradiation reflection from the nanoantenna emitter. Finally, single- and three-layer graphene are introduced to provide a real-time tuning of the infrared signature of the proposed nanoantenna emitter (design II). It is also demonstrated that the three-layer graphene structure can suppress an undesired absorption resonance wavelength related to the intrinsic vibrational modes (optical phonons) of the SiO 2 layer by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>53.19</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:math> compared to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>25.53</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:math> for the single-layer one. The spectral analysis of design I is validated using both analytical and numerical approaches where the numerical simulation domain is extended for the analysis of design II. The thermal characteristic analyses of design I and design II (without/with graphene layers) reveal that infrared signatures of the blackbody radiation are significantly reduced for the whole wavelength spectrum at least by <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>96</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>91</mml:mn> <mml:mi mathvariant="normal">%</mml:mi> </mml:math> within a wide temperature ranging from room temperature to <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>500</mml:mn> <mml:mrow> <mml:mtext>K</mml:mtext> </mml:mrow> </mml:math> , respectively.