High-Q Multiband Narrowband Absorbers Based on Two-Dimensional Graphene Metamaterials

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The paper investigated graphene-based metamaterial absorbers operating at THz range. 

1           In the introduction section, “In fact, narrow-band absorption is mainly realized by using Fabry-Perot resonators, metallic gratings, photonic crystals, and guided-wave resonances” was stated. However, many plasmonic metamaterials has been proposed for narrow-band absorption. Please revise this sentence.

2           The multi-band absorption using graphene-based metamaterials have been also proposed by many papers. Please clarify the novelty of this paper in detail.

3           As for “In the experimental process, an electron beam evaporation technique was used to deposit a gold film and a SiO2 isolation layer on a silicon substrate“, as shown in Fig. 1, Cu was used. Please consider again.

4            The chemical potential of graphene can be changed to maximum 1.0 eV. Please consider the actual value.

5           The effect of the relaxation time is interesting. However, the mobility is most important and can be measured for an actual graphene. Please discuss the effect of the mobility not relaxation time in the discussion section.

 

Minor points

Please add parameter name such as W2 above its values in the figure legend.

Author Response

Please see in attached.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The authors proposed narrowband multi-wavelength absorbers based on graphene metamaterials in the terahertz regime. The unit structure of the metamaterials consists of a copper back reflector, a silica insulating layer, and a top-patterned graphene layer. The graphene pattern is designed to have multiple absorption peaks in the THz regime. The pattern includes various geometries such as 'L,' '+,' and circular shape. The geometrical changes are thoroughly investigated to understand their contribution to the overall absorption spectra. Lastly, the authors investigate how changes in graphene chemical potential and relaxation times affect the absorption spectra for the potential development of a graphene-based tunable absorber. Additionally, the authors explore the potential of the proposed design for a refractive-index sensor.

Overall, the manuscript is well-written and scientifically sound. I believe the thorough investigation of the graphene-based absorber using numerical methods will be helpful for potential readers. Thus, I recommend the publication of this paper. Here are some minor comments on the manuscript:

1.     I found a typo in Line 134. 'the The absorptivity' should be revised to 'The absorptivity.' Please check whole manuscript thoroughly.

2.     It seems like the authors utilized some kind of optimization technique to determine the optimal geometrical parameters in Figure 1. Did the authors employ any specific optimization techniques or conduct any parameter sweeps in multi-parameter dimensions (i.e., simultaneously changing L1, W1, L2, W2, g, R1, R2)?

3.     I wonder if there is any way to modulate the frequency gap between absorption peaks while maintaining unity absorption peaks.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors addressed my comments.