Air Core ARROW Waveguides Fabricated in a Membrane-Covered Trench
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript reports on a hollow core waveguide fabrication and characterization.
Very unfortunate that several essential parts of the study are missing. Since the work has a potential interest, I propose adding a set of studies and resubmitting for consideration.
1. Hollow core fibers were completely overlooked in the discussion.
2. Modal analyses as a function of the structure parameters are missing. It is a rather straightforward electromagnetic calculation.
3. After accomplishing 2, potential geometries can be discussed.
4. Fig. 1 demonstrates fabrication stages – material and approaches are not clear at all.
5. Through the report the authors say that 3-4 different geometries were considered – I see only 1 device in Fig. 2. No comparison has been made.
6. Fig 3 – can you, please, make calculations for several parameters, demonstrate their impact, etc?
7. The impact and relevance of a smell strip on top of the curved surface is not clear – which impact it has on the mode formation?
8. Fig 4 – the comparison is not clear, please, add SEM images of the devices, please, add measured profiles, please, add calculations.
I believe that after some efforts the report can become interesting, but, by now, it lacks a lot of important data.
Comments on the Quality of English LanguageThere are sentences that can be improved in terms of style. No critical language issues were found.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe article reports on the design, fabrication, and characterization of novel hollow core anti-resonant reflecting optical waveguides (ARROWs) fabricated in a membrane covered trench. Four waveguide designs are demonstrated, which have different numbers of thin film reflecting layers.
The main novelty of the work regards the described structures.
The content of the article is within the scope of the Journal.
Conclusions are in accordance with the derived results.
A merit of the paper is that it proposes and evaluates (by means of measurements) actual waveguide structures.
Specific comment
Indices should be put in di, ni and nc (lines 60-64).
Use of English
The article is generally well written, so regarding the use of English a minor editing would be sufficient.
Review decision
I consider the article publishable practically as it is (with only a minor editing regarding the use of English).
Comments on the Quality of English LanguageThe article is generally well written, so regarding the use of English a minor editing would be sufficient.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for Authors
This paper proposes a new structure of hollow core anti-resonant reflecting optical waveguides (ARROWs) to reduce the optical loss of waveguide. This ARROW structure combines an etched trench with a thin top membrane. To enable horizontal mode confinement, a rib structure is built into this top membrane. Four waveguide designs are demonstrated, which have different numbers of thin film reflecting layers. And the optical loss has been characterized, which decreases with additional reflecting layers. The measured lowest loss coefficient is 1 cm-1 for a mode on the order of 10 µm x 15 µm.
The paper is well written, but the description of some important points is inadequate or missing. Therefore, there are some problems, which must be solved before it is considered for publication.
1. In the introduction, please provide more detailed information on current progress in ARROW, such as the difficulties in their studies.
2. In the introduction, the cited references of applications mostly are not recent publications (within the last 5 years) which need to be change.
3. In the part 2, please add a schematic diagram of this ARROW structure in order to show your idea more clearly.
4. Figure 1 is not easy to understand, please add some notes which is related to the text in part 3.
5. Line 71-73: please show us the data to prove the conclusion.
6. Figure 3: please add a color bar.
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Comments and Suggestions for Authors.
Author Response
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Author Response File: Author Response.docx
