A Hybrid Design for Frequency-Independent Extreme Birefringence Combining Metamaterials with the Form Birefringence Concept
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis work investigated an artificial birefringence using anisotropic metamaterials and grating structures composed of the designed MMs and air gaps. All results were obtained numerically or theoretically. The authors claimed that the designed structure shows a high magnitude of birefringence and is almost flat at around 0.16 THz.
I understand the concept of a combination of anisotropic MMs and multilayered anisotropy. However, I am not convinced that achieved results originate from the author's concept because I couldn't understand the core explanation in 3.3. Especially, paragraphs 6 and 7 in 3.3 were hard to understand. They said, "The device design should have a volume fraction close to unity in order to have a large birefringence." But, I couldn't understand their claim from the figures.
I think the methodology itself is scientifically sound, therefore, if the authors can clarify the main point of their study, it is worth to considering the publication.
Minor points:
1. I couldn't find the Ref. 44 in the reference list.
2. I think there are about 10 self citations in the reference. It may be too many.
3. The definition of Delta_n should be described explicitly.
Author Response
"Please see the attachment."
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsNotes to the manuscript by Can Koral and Fulya Bagci
1. It is advisable to mention in the manuscript previously performed studies of superlattices, which were of considerable interest at the time. These are also periodic structures with many layers, considered in the long-wave approximation. Such a mention would be appropriate, since formulas (6-7) are very close to similar formulas for superlattices. In this regard, the metamaterial in the article can be considered a superlattice, the layers of which are parallel to the air grooves.
2. It is advisable to check the correctness of references to the literature. For example, on page 3, line 119 should probably have reference 32 instead of 33. And the article number 44 (see page 5, line 206) is not in the list at all.
3. On page 3, in lines 126 and 127, the dimensions should be in micrometers, not millimeters, so that this corresponds to the caption to Figure 1.
4. For a complete understanding by the reader, after formulas (1-2), the values i and k0 should be explained.
5. What does the stroke before the curly bracket at the end of formula 5 mean? You need to explain or delete it.
6. In formulas (6-7), the values n1,TE and n1,TM are used. Further in the text, in formulas (8-9) values nTE,1 and nTM,1 are used for which the indexes are written in reverse order. Are these different values or are they the same?
7. On page 6, lines 228 and 230 should have THz instead of GHz.
8. On page 6, figures 3 (a) and (b) should be indicated in line 243.
9. In the captions to Figures 4, 5 and 6, it is more logical to write "Plots", since there are several curves.
Author Response
"Please see the attachment."
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThank you for the efforts to improve the manuscript and replying to my questions. I think the paper was improved and is acceptable for publication.
