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Experimental demonstration of a transparent graphene millimetre wave absorber with 28% fractional bandwidth at 140 GHz.

Wu B, Tuncer HM, Naeem M, Yang B, Cole MT, Milne WI, Hao Y - Sci Rep (2014)

Bottom Line: Broadband absorption is a result of mutually coupled Fabry-Perot resonators represented by each graphene-quartz substrate.Millimetre wave reflectometer measurements of the stacked graphene-quartz absorbers demonstrated excellent broadband absorption of 90% with a 28% fractional bandwidth from 125-165 GHz.Our data suggests that the absorbers' operation can also be extended to microwave and low-terahertz bands with negligible loss in performance.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Electronic Engineering and Computer Science, Queen Mary University of London, London, E1 4NS, United Kingdom [2] School of Electronic Engineering, Xidian University, Xi'an, 710071, China.

ABSTRACT
The development of transparent radio-frequency electronics has been limited, until recently, by the lack of suitable materials. Naturally thin and transparent graphene may lead to disruptive innovations in such applications. Here, we realize optically transparent broadband absorbers operating in the millimetre wave regime achieved by stacking graphene bearing quartz substrates on a ground plate. Broadband absorption is a result of mutually coupled Fabry-Perot resonators represented by each graphene-quartz substrate. An analytical model has been developed to predict the absorption performance and the angular dependence of the absorber. Using a repeated transfer-and-etch process, multilayer graphene was processed to control its surface resistivity. Millimetre wave reflectometer measurements of the stacked graphene-quartz absorbers demonstrated excellent broadband absorption of 90% with a 28% fractional bandwidth from 125-165 GHz. Our data suggests that the absorbers' operation can also be extended to microwave and low-terahertz bands with negligible loss in performance.

No MeSH data available.


Related in: MedlinePlus

Comparison of calculated and measured spectra of single graphene-quartz absorbers.(a, c) Calculated absorption spectra. The scattering rates are chosen as Γ = 7 meV for μc = 0.0 eV and Γ = 5 meV for all others, T = 300 K. (b, d) Measured reflection and absorption spectra of single (N = 1) graphene-quartz absorbers with 1–4 L graphene on quartz (εr = 3.8 and h = 1.3 mm). The measurements show that the improvement in absorption is substantial from 1 L to 2 L multilayer graphene while less significant after 2 L. The measured reflection and absorption spectra in (b) and (d) are similar to calculated spectra in (a) and (c).
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f3: Comparison of calculated and measured spectra of single graphene-quartz absorbers.(a, c) Calculated absorption spectra. The scattering rates are chosen as Γ = 7 meV for μc = 0.0 eV and Γ = 5 meV for all others, T = 300 K. (b, d) Measured reflection and absorption spectra of single (N = 1) graphene-quartz absorbers with 1–4 L graphene on quartz (εr = 3.8 and h = 1.3 mm). The measurements show that the improvement in absorption is substantial from 1 L to 2 L multilayer graphene while less significant after 2 L. The measured reflection and absorption spectra in (b) and (d) are similar to calculated spectra in (a) and (c).

Mentions: The measured reflection and absorption spectra of single graphene-quartz absorbers with 1–4 L graphene on quartz are compared with analytical calculations in Fig. 3. The calculated results in Fig. 3a and 3c show the influence of the chemical potential on the reflection and absorption properties of the absorber. When μc = 0 eV and Γ = 7 meV, this corresponds to a sheet resistance of 5044 Ω/sq which makes the input impedance challenging to match with free space. The peak absorption is lower than 40% indicating a poor absorption. As the chemical potential increases, in steps of μc = 0.1 eV, the sheet resistance of graphene is reduced and the peak absorption improves. When μc = 0.3 eV and Γ = 5 meV, the corresponding sheet resistance is 430 Ω/sq, which tends toward the free space impedance. Good impedance matching leads to 100% peak absorption around 148 GHz.


Experimental demonstration of a transparent graphene millimetre wave absorber with 28% fractional bandwidth at 140 GHz.

Wu B, Tuncer HM, Naeem M, Yang B, Cole MT, Milne WI, Hao Y - Sci Rep (2014)

Comparison of calculated and measured spectra of single graphene-quartz absorbers.(a, c) Calculated absorption spectra. The scattering rates are chosen as Γ = 7 meV for μc = 0.0 eV and Γ = 5 meV for all others, T = 300 K. (b, d) Measured reflection and absorption spectra of single (N = 1) graphene-quartz absorbers with 1–4 L graphene on quartz (εr = 3.8 and h = 1.3 mm). The measurements show that the improvement in absorption is substantial from 1 L to 2 L multilayer graphene while less significant after 2 L. The measured reflection and absorption spectra in (b) and (d) are similar to calculated spectra in (a) and (c).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3928574&req=5

f3: Comparison of calculated and measured spectra of single graphene-quartz absorbers.(a, c) Calculated absorption spectra. The scattering rates are chosen as Γ = 7 meV for μc = 0.0 eV and Γ = 5 meV for all others, T = 300 K. (b, d) Measured reflection and absorption spectra of single (N = 1) graphene-quartz absorbers with 1–4 L graphene on quartz (εr = 3.8 and h = 1.3 mm). The measurements show that the improvement in absorption is substantial from 1 L to 2 L multilayer graphene while less significant after 2 L. The measured reflection and absorption spectra in (b) and (d) are similar to calculated spectra in (a) and (c).
Mentions: The measured reflection and absorption spectra of single graphene-quartz absorbers with 1–4 L graphene on quartz are compared with analytical calculations in Fig. 3. The calculated results in Fig. 3a and 3c show the influence of the chemical potential on the reflection and absorption properties of the absorber. When μc = 0 eV and Γ = 7 meV, this corresponds to a sheet resistance of 5044 Ω/sq which makes the input impedance challenging to match with free space. The peak absorption is lower than 40% indicating a poor absorption. As the chemical potential increases, in steps of μc = 0.1 eV, the sheet resistance of graphene is reduced and the peak absorption improves. When μc = 0.3 eV and Γ = 5 meV, the corresponding sheet resistance is 430 Ω/sq, which tends toward the free space impedance. Good impedance matching leads to 100% peak absorption around 148 GHz.

Bottom Line: Broadband absorption is a result of mutually coupled Fabry-Perot resonators represented by each graphene-quartz substrate.Millimetre wave reflectometer measurements of the stacked graphene-quartz absorbers demonstrated excellent broadband absorption of 90% with a 28% fractional bandwidth from 125-165 GHz.Our data suggests that the absorbers' operation can also be extended to microwave and low-terahertz bands with negligible loss in performance.

View Article: PubMed Central - PubMed

Affiliation: 1] School of Electronic Engineering and Computer Science, Queen Mary University of London, London, E1 4NS, United Kingdom [2] School of Electronic Engineering, Xidian University, Xi'an, 710071, China.

ABSTRACT
The development of transparent radio-frequency electronics has been limited, until recently, by the lack of suitable materials. Naturally thin and transparent graphene may lead to disruptive innovations in such applications. Here, we realize optically transparent broadband absorbers operating in the millimetre wave regime achieved by stacking graphene bearing quartz substrates on a ground plate. Broadband absorption is a result of mutually coupled Fabry-Perot resonators represented by each graphene-quartz substrate. An analytical model has been developed to predict the absorption performance and the angular dependence of the absorber. Using a repeated transfer-and-etch process, multilayer graphene was processed to control its surface resistivity. Millimetre wave reflectometer measurements of the stacked graphene-quartz absorbers demonstrated excellent broadband absorption of 90% with a 28% fractional bandwidth from 125-165 GHz. Our data suggests that the absorbers' operation can also be extended to microwave and low-terahertz bands with negligible loss in performance.

No MeSH data available.


Related in: MedlinePlus