Realization of 4 × 200 Gbps 4-QAM OFDM-OWC System Using Higher Order OAM Modes for HAP-to-Satellites Scenario

Round 1

Reviewer 1 Report

Overall, this paper presents major advancements in the field of photonics, specifically in the application of OAM multiplexing for enhancing satellite communication systems. The methodology is well-structured, and the results demonstrate the potential of the proposed system. 

Line 44: double use of "such as" in a sentence. May be rephrase this sentence?

Figure 2(a,b): the Y-axis label needs to corrected as they have the same label?

In general, could benefit from a more detailed explanation of the choice of LG modes and their expected impact on system performance

Lines 211-216: may be avoided as this is mostly reading off the plots. Instead, one could describe the best performer in words?

Figs. 3, 4, 5, and 7: LG modes can be added to the legend? Now, at a glance, all the plots look the same without reading the description. Also, the image resolution can be improved?

The authors carefully compared the latest results and set a bench mark standard with these results!

- There a few places which suffer from space issues like "1000km" in lines 232, 236, and 237.

- I suggest to use serial commas in all places, especially in figure description. If the authors decide not to use them at all, they should be consistent across all the occurrences.

Author Response

Responses to the comments from Reviewer #1

Overall, this paper presents major advancements in the field of photonics, specifically in the application of OAM multiplexing for enhancing satellite communication systems. The methodology is well-structured, and the results demonstrate the potential of the proposed system.

• Thank you for the suggestions. All minor comments have been addressed.

Comment 1): Line 44: double use of "such as" in a sentence. May be rephrase this sentence?

Response: Thank you. As suggested, the given sentence is corrected. Please see page no. 2.

Comment 2): Figure 2(a,b): the Y-axis label needs to corrected as they have the same label?

Response: Thank you for this suggestion. Figure 2(a,b): Y:axis label is corrected. Please see page no. 4-5.

Comment 3): In general, could benefit from a more detailed explanation of the choice of LG modes and their expected impact on system performance

Response: As suggested, the detailed explanation of the choice of LG modes and their expected impact on system performance is presented. Please see page no. 5-6.

Comment 4): Lines 211-216: may be avoided as this is mostly reading off the plots. Instead, one could describe the best performer in words?

Response: As suggested, the description of the plots are modified. Please see page no. 7-8.

Comment 5): Figs. 3, 4, 5, and 7: LG modes can be added to the legend? Now, at a glance, all the plots look the same without reading the description. Also, the image resolution can be improved?

Response: As per suggestion, LG modes are added in Figures 3, 4, 5 and 7. Besides, the images resolution is improved. Please see page no. 7, 8, 9 and 12.

Comment 6): The authors carefully compared the latest results and set a bench mark standard with these results!

Response: As per suggestion, a comparison Table 6 is presented for the exiting works and the proposed work.  Please see page no. 13-14.

Reviewer 2 Report

Please check the attached file.

Comments for author File: Comments.pdf

English should improve

Author Response

Responses to the comments from Reviewer #2

Paper title: Realization of 4×200Gbps 4-QAM OFDM-OWC system using higher order OAM modes for HAP-to-Satellites Scenario My decision is minor revision. This paper implemented an orbital angular momentum (OAM) multiplexed orthogonal frequency division multiplexing (OFDM) system using an OWC link. A space-to-air scenario is considered in which transmission pointing errors, geometric loss, turbulence, and additional link losses are taken into account to extend transmission range, system capacity, and throughput.

• Thank you for the suggestions. All issues have been addressed.

Comment 1): Figure 3, 6, and 7 should put in same page.

Response: Thank you for this suggestion.  Figures 3, 6 and 7 are put in same page. Please see page no. 7, 11 and 12.

Comment 2): Authors shoud put figure in one page - Quality of Figures 5-6 is not good.

Response: As per suggestions all figures are put on same pages. Please see page no. 7-12. Also, quality of figures is improved. Please see page no. 9 and 11.

Comment 3): Please update. - Conclusion part should update with more details about your works.

Response: Thank you. The conclusion part is updated with more details of the work. Please see page no. 14.

Comment 4): Ref. 12 did not show in manuscript

Response: As per suggestion, all references are updated. Please see page no. 2 for given reference.

Comment 5): Check reference part be carefully

Response: As per suggestion, all references are updated.

Comment 6): Authors should compared your works with another works in Introduction part to highlight novelties of your works. Finally, I hope you will solve all the issues that I mentioned above to make your paper better.

Response: Thank you. As suggested, the proposed work is compared with other works in introduction part.  Please see page no. 2.

Besides, the novelties of the work is presented on Page no. 3.

Reviewer 3 Report

The paper proposes a 4×200Gbps OFDM-OWC system using OAM multiplexing for HAP to-satellite communication. There are used four higher-order OAM modes, namely LG mode at [0,0], [0,13], [0,40], and [0,80], to enhance the system performance over long-range and high-throughput OWC links.

The proposed system leads to good performances, compared with the existing ones. The evaluation was done in terms of constellation diagrams, eye patterns, and optical spectra.

The paper has an interesting subject. It is carefully written and technically sound. It is clearly presented and well organized. It has a good informational value in showing the state-of-the-art achieved.The references are appropriate. The conclusions are consistent.

The proposed systems from figure 1 and the results from figures 2 can be more detailed.

There are minor errors of English language.

Author Response

Responses to the comments from Reviewer #3

The paper proposes a 4×200Gbps OFDM-OWC system using OAM multiplexing for HAP to-satellite communication. There are used four higher-order OAM modes, namely LG mode at [0,0], [0,13], [0,40], and [0,80], to enhance the system performance over long-range and high-throughput OWC links.

The proposed system leads to good performances, compared with the existing ones. The evaluation was done in terms of constellation diagrams, eye patterns, and optical spectra.

The paper has an interesting subject. It is carefully written and technically sound. It is clearly presented and well organized. It has a good informational value in showing the state-of-the-art achieved.The references are appropriate. The conclusions are consistent.

• Thank you for the suggestions. All issues have been addressed.

Comment 1): The proposed systems from figure 1 and the results from figures 2 can be more detailed.

Response: As per suggestion, Figure 1 and Figure 2 are explained well. Please see page no. 4-6.

Thanks you again.