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Intensity tunable infrared broadband absorbers based on VO2 phase transition using planar layered thin films.

Kocer H, Butun S, Palacios E, Liu Z, Tongay S, Fu D, Wang K, Wu J, Aydin K - Sci Rep (2015)

Bottom Line: Here, we demonstrate a simple, lithography-free approach for obtaining a resonant and dynamically tunable broadband absorber based on vanadium dioxide (VO2) phase transition.Using planar layered thin film structures, where top layer is chosen to be an ultrathin (20 nm) VO2 film, we demonstrate broadband IR light absorption tuning (from ~90% to ~30% in measured absorption) over the entire mid-wavelength infrared spectrum.Broadband tunable absorbers can find applications in absorption filters, thermal emitters, thermophotovoltaics and sensing.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208, USA.

ABSTRACT
Plasmonic and metamaterial based nano/micro-structured materials enable spectrally selective resonant absorption, where the resonant bandwidth and absorption intensity can be engineered by controlling the size and geometry of nanostructures. Here, we demonstrate a simple, lithography-free approach for obtaining a resonant and dynamically tunable broadband absorber based on vanadium dioxide (VO2) phase transition. Using planar layered thin film structures, where top layer is chosen to be an ultrathin (20 nm) VO2 film, we demonstrate broadband IR light absorption tuning (from ~90% to ~30% in measured absorption) over the entire mid-wavelength infrared spectrum. Our numerical and experimental results indicate that the bandwidth of the absorption bands can be controlled by changing the dielectric spacer layer thickness. Broadband tunable absorbers can find applications in absorption filters, thermal emitters, thermophotovoltaics and sensing.

No MeSH data available.


Absorption map with respect to PMMA thickness sweep for (a) i-VO2 (b) m-VO2 structure. The colorbar applies both.
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f2: Absorption map with respect to PMMA thickness sweep for (a) i-VO2 (b) m-VO2 structure. The colorbar applies both.

Mentions: Both Finite-Difference Time-Domain (FDTD) and Transfer Matrix Method (TMM) techniques are used for electromagnetic modelling. A plane wave source is assumed to be normally incident and propagate along y-axis through the structures. Complex refractive indices for two different phases (insulator and metal) of VO2 film were taken from an earlier experimental study27. Index of the PMMA and sapphire were set to constant values of 1.47 and 1.7, respectively. The complex refractive index of Au were taken from the Palik database34. The relative dielectric permittivities of the materials used in the simulations are given in Supplementary Figure S1. The effect of the thickness of the PMMA (dielectric) spacer layer were investigated using numerical simulations for i-VO2 and m-VO2 as shown in Fig. 2. Transmitted and reflected power from these absorbers were computed using transmission and reflection power monitors and the absorption was calculated by using equation (1). Simulations show that beyond the first Fabry-Perot mode, both i-VO2 and m-VO2 have a fairly constant and broadband absorption profile. However, the absorption of m-VO2 is substantially enhanced compared to i-VO2 in the MWIR spectrum. The thickness of PMMA determines the spectral position of the first order Fabry-Perot mode as expected.


Intensity tunable infrared broadband absorbers based on VO2 phase transition using planar layered thin films.

Kocer H, Butun S, Palacios E, Liu Z, Tongay S, Fu D, Wang K, Wu J, Aydin K - Sci Rep (2015)

Absorption map with respect to PMMA thickness sweep for (a) i-VO2 (b) m-VO2 structure. The colorbar applies both.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4543955&req=5

f2: Absorption map with respect to PMMA thickness sweep for (a) i-VO2 (b) m-VO2 structure. The colorbar applies both.
Mentions: Both Finite-Difference Time-Domain (FDTD) and Transfer Matrix Method (TMM) techniques are used for electromagnetic modelling. A plane wave source is assumed to be normally incident and propagate along y-axis through the structures. Complex refractive indices for two different phases (insulator and metal) of VO2 film were taken from an earlier experimental study27. Index of the PMMA and sapphire were set to constant values of 1.47 and 1.7, respectively. The complex refractive index of Au were taken from the Palik database34. The relative dielectric permittivities of the materials used in the simulations are given in Supplementary Figure S1. The effect of the thickness of the PMMA (dielectric) spacer layer were investigated using numerical simulations for i-VO2 and m-VO2 as shown in Fig. 2. Transmitted and reflected power from these absorbers were computed using transmission and reflection power monitors and the absorption was calculated by using equation (1). Simulations show that beyond the first Fabry-Perot mode, both i-VO2 and m-VO2 have a fairly constant and broadband absorption profile. However, the absorption of m-VO2 is substantially enhanced compared to i-VO2 in the MWIR spectrum. The thickness of PMMA determines the spectral position of the first order Fabry-Perot mode as expected.

Bottom Line: Here, we demonstrate a simple, lithography-free approach for obtaining a resonant and dynamically tunable broadband absorber based on vanadium dioxide (VO2) phase transition.Using planar layered thin film structures, where top layer is chosen to be an ultrathin (20 nm) VO2 film, we demonstrate broadband IR light absorption tuning (from ~90% to ~30% in measured absorption) over the entire mid-wavelength infrared spectrum.Broadband tunable absorbers can find applications in absorption filters, thermal emitters, thermophotovoltaics and sensing.

View Article: PubMed Central - PubMed

Affiliation: Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208, USA.

ABSTRACT
Plasmonic and metamaterial based nano/micro-structured materials enable spectrally selective resonant absorption, where the resonant bandwidth and absorption intensity can be engineered by controlling the size and geometry of nanostructures. Here, we demonstrate a simple, lithography-free approach for obtaining a resonant and dynamically tunable broadband absorber based on vanadium dioxide (VO2) phase transition. Using planar layered thin film structures, where top layer is chosen to be an ultrathin (20 nm) VO2 film, we demonstrate broadband IR light absorption tuning (from ~90% to ~30% in measured absorption) over the entire mid-wavelength infrared spectrum. Our numerical and experimental results indicate that the bandwidth of the absorption bands can be controlled by changing the dielectric spacer layer thickness. Broadband tunable absorbers can find applications in absorption filters, thermal emitters, thermophotovoltaics and sensing.

No MeSH data available.