Plasmonic Fishnet Structures for Dual Band THz Left-Handed Metamaterials
Round 1
Reviewer 1 Report
The authors present a design of a metasurface simultaneously exhibiting negative permittivity and permeability at two distinct THz frequencies. This concept has been rigorously verified with brute-force simulations. The results presented in the manuscripts might be of interest to the photonics community. The manuscript can be accepted for publication in Photonics, although I believe the manuscript can be slightly improved to enhance its impact.
- In the introductory section, a clear justification of the importance of designing dual-band left-handed metasurfaces would be highly appreciated. The Authors state in lines 30-32 "..To promote LHMs engineering application, it is necessary to improve their electromagnetic properties and realize broad bandwidth, dual-band or multi-band LHMs..", but it is unclear what is particular benefit from such multiband metasurfaces? How this feature can be used in one or another practical application?
- Figures 4 and 5: I would rather replace the term "measured" with the term "calculated" - it is not a real experiment, this is a simulation;
- It will be instructive to add to Figures 4 and 5 respective curves from Figure 2b for the sake of comparison between effective medium theory predictions and rigorous calculations.
Author Response
Point 1: In the introductory section, a clear justification of the importance of designing dual-band left-handed metasurfaces would be highly appreciated. The Authors state in lines 30-32 ".To promote LHMs engineering application, it is necessary to improve their electromagnetic properties and realize broad bandwidth, dual-band or multi-band LHMs.", but it is unclear what is particular benefit from such multiband metasurfaces? How this feature can be used in one or another practical application?
Response 1:Thank you for your comments. Actually, in most applications, such as antennas, sensors and imaging, broad bandwidth or multi-band LHMs are required. We have demonstrate those applications in the revised manuscript. Please refers to lines 31-35. In addition, some references have been supplemented. Please refers to Refs[15]-[20].
Point 2: Figures 4 and 5: I would rather replace the term "measured" with the term "calculated" - it is not a real experiment, this is a simulation;
Response 2: Thank you very much. We have revised it now.
Point 3: It will be instructive to add to Figures 4 and 5 respective curves from Figure 2b for the sake of comparison between effective medium theory predictions and rigorous calculations.
Response 3: Thank you very much. Figure 2b has been added to Figs. 4 and 5 of revised manuscript according to the comment.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Review in the attachment
Comments for author File: 
Comments.pdf
Author Response
Point 1: It’s well known that metamaterials based on fishnet structures are quite well described. So what is the unique property of the proposed model? This should be fully explained in the introduction.
Response 1: Thank you for the suggestion. The unique property of our proposed model is that THz dual-band negative refractions are realized through the stacked LHMs structure. We have supplemented some descriptions about the unique properties in the revised manuscript. Please refers to lines 43-44.
Point 2: The authors write that new concepts of metamaterial devices in the THz range “are still critically needed”, but do not mention the last few proposals for such devices, e.g. Active control of terahertz radiation using a metamaterial loaded with a nematic liquid crystal, Liq. Cryst., 43:8, 1120-1125, (2016); Transient transmission of THz metamaterial antennas by impact ionization in a silicon substrate," Opt. Express 29, 170-181 (2021), etc.
Response 2:Thank you for your comments, the references have been cited in the revised manuscript now. Please refers to Refs[15],[22].
Point 3: The authors should provide a detailed explanation of which elements of the metasurface are responsible for negative values of permittivity and permeability. For this purpose, the interaction of the proposed metastructure with the incident THz radiation should be described in detail. The authors simply include the simulation results, but there is no thorough explanation of their physical meaning.
Response 3: Thank you very much. Detailed explanation has been supplemented in the revised manuscript. Please refers to lines 105-114.
Point 4: The conclusions are written very generally and they resemble the abstract. There is practically no reference to the results.
Response 4: The conclusions have been rewritten now.
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
The authors responded carefully to all my comments and tips. The manuscript should be published as is.
