Review Reports - A Multiplexing Optical Temperature Sensing System for Induction Motors Using Few-Mode Fiber Spatial Mode Diversity

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors of this manusript did important work to measure the temperature of induction motors by FMF FBGs. I suggest the authors describe some necessary details in the abstact and conclusion sections, such as temperature range for measurement, accuracy obtained, speed/load of the motors and some on, and highlight its innovative value. The last sentence in the abstract is not appropriate, because the manuscript only solves the issue for temperature measurement, not the mutiple physical fields. In addtion, common FBGs with single mode fiber and weak reflection FBGs have been applied to the same or similar objects, so, the obvious or potential advantages of the FMF FBGs should be highlighted by some discussion or analysis in the intorducton and conclusion.

Comments on the Quality of English Language

The Quality of English Language in the manuscript is good.

Author Response

Response Letter

Dear Reviewer：

Gratefully thank you for your valuable advices on our manuscript. According to your comments, essential corrections and additions have been made in the revised version of this paper. Please see the attachment for a detailed reply to your comments.

Thank you very much for your consideration!

Best regards,

Sincerely

Feng Liu

liufeng@wzu.edu.cn

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This research is about a multiplexing optical temperature sensing system for induction motors using few-mode fiber spatial mode diversity. Mainly by designing the FMF.FBG to monitor the temperature of the motors. Through the experimental analysis, the sensing system is reasonable and has certain application value. But there are some issues to be addressed as follow:

(1) In the abstract part, the author should add some background about this research in brief.

(2) Please provide more related research reference, in present form, the background is insufficient.

(3) In part 2: this part is confusing and not clear about the experimental principle and setup, please describe the composition of the experimental system separately.

(4) In Fig.2 : What's the evidence of mathematical expressions and corresponding fitting results, especially about the fit coefficient, please give more reference.

(5) The conclusions are weak, please give more information about this research , including the imitations and further research.

Author Response

Response Letter

Dear Reviewer：

Thank you very much for your consideration!

Best regards,

Sincerely

Feng Liu

liufeng@wzu.edu.cn

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

The proposed manuscript regards a spatial modes-based fiber optic sensors for temperature monitoring of the stator winding. The article is well written but some crucial information is missing. Due to this, the novelty is not appreciable. Here I suggest some comment to improve the article to be suitable for pubblication.

- in the introduction there's the sentence "This serial topology has 80 comparatively lower reliability. In instances where a single FBG unit is damaged, it can 81 lead to a network failure in the subsequent system, thus reducing the reliability of the 82 multiplexed sensing system [17,18]." But in the proposed technology I don't see something that overcomes this limit. The kind of network proposed in figure 1 can be employed also for normal FBG sensors with DWDM-based interrogation system.

- the theoretical part in section 2 explaining the different FBG spatial mode is not clear at all. I don't understand if we are still talking about FBG structure playing with different mode to demodulate the signal, or if we are talking about different structure compared with FBG sensors.

- I don't get if the device "photonic lantern" is designed by the authors or if is something got from the market. Again, which is the difference with a simple 4-channel wavelength demultiplexer interrogating 4 FBG array (compared for this case)?

- please spend more words regarding the interrogation performed, referred to figure 1. The signal was acquired with an OSA and processed digitally. Which is the proposed interrogation algorithm?

- As it is well known from the state-of-art, interrogation with OSA shows many limit to the FBG sensor interrogation. Authors should provide information to enhance the advantages of the proposed technology with the state-of-art (resolution, accuracy, speed, etc.).

- in Figure 2 the sensor calibration in temperature is shown. Usually, for this wide temperature range a cubic fit is employed. Please show the fit related data and compare (and comment) the result with a cubic fit.

- please improve figure 5 with a legend explaining the difference between full and dotted line. Here I don't understand if the full line are curve fitting. If so, please provide fit data.

- please improve conclusions with a deeper explanation of what was done.

Author Response

Response Letter

Dear Reviewer：

Thank you very much for your consideration!

Best regards,

Sincerely

Feng Liu

liufeng@wzu.edu.cn

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

Thanks for authors' revision. I think the paper can be published in current form.

Author Response

Dear Reviewer,

I hope this message finds you well. I am writing to express my sincere gratitude for the positive outcome of the peer review process for our manuscript titled "A Multiplexing Optical Temperature Sensing System for induction motors Using Few-mode Fiber Spatial Mode Diversity". I am delighted to learn that the reviewers have found our work to be suitable for publication in Electronics.

I would also like to extend my appreciation to the reviewers for their insightful comments and constructive feedback, which have greatly helped to enhance the quality and clarity of our research. Please let me know if there are any further steps we need to take or any additional information you require from us to move forward with the publication process.

Thank you once again for the opportunity to contribute to Electronics. I am looking forward to the final publication of our work.

Best regards,

Feng Liu

Wenzhou University

liufeng@wzu.edu.cn

Reviewer 3 Report

Comments and Suggestions for Authors

I'd like to congrat with authors for the very satisfying response. All the suggestions I have raised in my first review were got from the authors and the manuscript is substantially improved.

In my opinion, the article is almost ready for pubblication. I'd like to push to the first comment I raised again, since I'm not satisfied at all with the authors response.

I try to explain again my point of view:

the sentence "This serial topology has 80 comparatively lower reliability. In instances where a single FBG unit is damaged, it can 81 lead to a network failure in the subsequent system, thus reducing the reliability of the 82 multiplexed sensing system [17,18]." is, in my opinion, too strong. Actually, talking about the responses provided by authors, in Fig 2 many FBG in the same array were put, but in Fig 1 just one FBG per array is installed, so the comparison is not valid. Regarding the differences between Fig 3 and Fig 4, I'd like to suggest to the authors that is very easy to implement the same configuration also in Fig 4 just putting a coupler, an y-splitter, a passive demultiplexer and have a parallel configuration without use the spatial mode and MM fiber needed for the configuration proposed.

However, the article has merits, many studies have been reporter as well as calibration; very nice design and, in my opinion, this may lead to others intersting application if carried on.

For what just said, I recommend to modify the sentence reported (again, it is too strong because, actually, I don't observe a real solution to the reliability problem with this approach), motivating differences (as reported in the authors response) of the proposed technique with WDM-based interrogation system at the state-of-art. I report some reference to add, to help authors with similiar configuration that works optimally with a parallel configuration for multiple array connection (e.g., connecting an AWG to the FBG side).

[1] A. J. Willshire, P. Niewczas, and J. R. Mcdonald, “A cyclic arrayed-waveguide-grating-based fiber-optic sensor interrogation system,” IEEE Photonics Technol. Lett., vol. 18, no. 18, pp. 1904–1906, 2006, doi: 10.1109/LPT.2006.881651.

[2] V. R. Marrazzo et al., “Experimental Tests of a Full Analog Fiber Optic Monitoring System Suitable for Safety Application at CERN,” IEEE Trans. Instrum. Meas., vol. 72, 2023, doi: 10.1109/TIM.2023.3250283.

[3] K. Li, P. Yuan, L. Lu, M. Dong, and L. Zhu, “PLC-Based Arrayed Waveguide Grating Design for Fiber Bragg Grating Interrogation System,” Nanomaterials, vol. 12, no. 17, 2022, doi: 10.3390/nano12172938.

[4] M. Perry, P. Orr, P. Niewczas, and M. Johnston, “High-Speed Interferometric FBG Interrogator Measurement Capability,” J. Light. Technol., vol. 31, no. 17, pp. 2897–2903, 2013.

[5] V. R. et al. Marrazzo, “IoT Node Interrogation System for Fiber Bragg Grating Sensors: Design, Characterization and On-Field Test,” IEEE Trans. Instrum. Meas., 2024, doi: 10.1109/TIM.2024.3368488.

Finally, please report Fig 3 in the manuscript as first figure, since it is well explanatory.

Author Response

Dear Reviewer,

Thank you once again for the opportunity to contribute to Electronics. I am looking forward to the final publication of our work.

Best regards,

Feng Liu

Wenzhou University

liufeng@wzu.edu.cn

Author Response File: Author Response.pdf