Multi-Physical Analysis and Optimization in Integrated Lithium Niobate Modulator Using Micro-Structured Electrodes

Round 1

Reviewer 1 Report

This manuscript developed a simulation model of a modulator equipped with slow-wave electrodes and  simulated the  heat generation of MW and Light signals. Authors analyzed the heat distribution and phase shift caused by heat, then gave us a great solution - adding a diamond film heat dissipation layer. The results are helpful for the LNOI modulator design.

 

To further improve the readability of the article, the following points should be improved:

1. Please finger out the simulation software used in this work.

2. Please indicate the input power of microwave and light in the simulation, which directly affect the max temperature and thermal distribution of the modulator.

3. There is a mixing problem with the size parameters in Figure 1a and c, such as ws & g, please correct it.

4. References 8 and 9 are duplicated; The format and information of some Refs. need to be corrected, such as person names, journals, volume numbers, page numbers, etc,

 

Overall, I would recommend this work to be published in this journal after appropriate revisions.

 

Author Response

Dear Reviewer, hello. Thank you very much for your valuable suggestions. We have made revisions based on your opinions. Please see the "Response to Review" document for specific replies. We hope that our response will satisfy you, and we welcome any other suggestions you may have.

Author Response File: Author Response.pdf

Reviewer 2 Report

The paper ‘Multi-physical analysis and optimization in integrated LN modulator usnig micro-structured electrodes’ describes a LN base on-chip device for MW heating. Authors model distribution of different physical parameters (light, electric field) at certain conditions. The device was found to heat too much and authors offered a heat-dissipating base (diamond, but can be other similar material).

 

The research is made with a high quality. But I feel lack of methods description. Authors strongly base their work on ref. 13, but this work should describe at least some details: how the calculation was performed, what programs or equipment was used, what algorithms were applied for calculation. It is important to state how exactly the authors have obtained the results. I did not see such a description quite clearly.

Thus, I recommend Major revision before the paper can be published.

 

There are some minor mistakes and typos.

1. Increase/decrease IN – and always IN.

2. The number 3 in a LiNbO3 formula is often in normal font, but should be in lowercase.

3. If you use abbreviation of lithium niobate as LN in the very beginning of the paper, you should use it everywhere in the manuscript text.

4. Figure 1 should clearly show where LN is, where other materials are. I understand that you gave a reference 13, but the readers read this paper for the first time, they are not aware of what is where in Fig. 1.

5. Line 48 – k0 IS wave vector.

6. Line 85 – Siemens is denotes as ‘S’, it should be’ 41 x 10^6 S/m’.

7. Decrees Celcius - °C.

8. Section 4 – what is S parameter? This should be described in detail. What is the difference between S21 and S11 parameters?

9. Line 172 – it should be μm, not um.

10. Some recommendations on cited literature:

Please, add DOI to references where possible.

Ref. 7 – should it be 11 or 110 GHz?

Ref. 10, 15 – authors should give more details on this reference. If this is a book, than add publisher, city or country of the publisher and number of pages.

Ref. 11, 13, 17, 17 – the references are papers, they should have pages or the number of the paper in the Journal. Adding DOI will release the mistake – DOI is unique and if some metadata of the paper is unknown, DOI will help to find it.

English is OK despite some minor typos. 

Author Response

Dear Reviewer, thank you very much for your valuable suggestions. We have made revisions based on your opinions. Please see the "Response to Review" document for specific replies. We hope that our response will satisfy you, and we welcome any other suggestions you may have.

Author Response File: Author Response.pdf

Reviewer 3 Report

Figure 1 needs to be redone; the geometric dimensions are very poorly visible, and it is also unclear what the two light spots on panel (b) are.

Figure 3a needs to be redone; on the presented scale, the distribution of the MW field is extremely poorly visible.

The text of the article does not indicate the stoichiometry of lithium niobate. There is also no indication of the type of diamond (natural or synthetic, obtained by CVD or HPHT).

There is no explanation of how the system of equations (1-3) was solved. If numerically, then it is necessary to specify the scheme, error, and variance.

From a practical point of view, some points are not clear:

-how will the diamond layer be attached (sputtering, gluing) and, accordingly, what will happen in the contact plane?

-if we take lithium niobate with surface metallization (Appl. Surf. Sci. 551, 149294 (2021)), will the results change?

Does the model take into account the effect of photorefraction?

In some figures, it is necessary to correct the spelling of the frequency.

References [2, 16] lack the names of the authors.

References [8] and [9] are duplicated.

Reference [10] lacks output.

Reference [7] contains an error in the title of the article.

In the formula for lithium niobate, index 3 should be lower.

Author Response

Dear Reviewer, thank you very much for your valuable suggestions. We have made revisions based on your opinions. Please see the "Response to Review" document for specific replies. We hope that our response will satisfy you, and we welcome any other suggestions you may have.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Everything is fine now. Paper can be published. Aythors have made a great job revising the paper. 

Author Response

Dear reviewer,

Thank you very much for agreeing to publish my paper after reviewing it. Your professional opinions and valuable suggestions are crucial to me, as they have helped me improve the quality and expression of my article. I deeply admire your diligent work and patient interpretation. Under your guidance, I have been able to eliminate the shortcomings in the article, highlighting the logicality of the arguments and the rigor of the evidence. I have also made some improvements in terms of wording and grammar based on your suggestions, making the entire article more fluent and clear. Thank you for your hard work and patience. I hope we can continue to collaborate in future submissions.

Sincerely,
Jianchao Su

Reviewer 3 Report

-In Fig. 5, 7, 11 spelling of the frequency is not corrected;

-Line 204 is missing a reference (""..layers on metals using CVD[]");

-I propose to add in the conclusions section the prospect of further research in this direction (the use of lithium niobate with surface metallization, taking into account the effect of photorefraction in lithium niobate, etc.);

-In the abstract, it is necessary to indicate the purity of lithium niobate and the origin of the diamond (CVD);

- There is an optional question: what is the approximate cost of such a modulator?

Author Response

Dear reviewer,

Thank you for your valuable time and suggestions. We sincerely apologize for the spelling errors in images 5,7and 11 that were missed in the previous revision. We have made the necessary corrections in the latest version. The citation error in line 204 has also been rectified. Additionally, based on your advice, we have included in the abstract the information regarding the purity of lithium niobate and the origin of the diamond. Moreover, in the final paragraph, we have added the prospect of further research in this direction, including the use of lithium niobate with surface metallization, taking into account the effect of photorefraction in lithium niobate, etc. 

Regarding the issue of the modulator cost that you mentioned, since the technology of depositing a diamond heat dissipation layer on metal is currently only found in laboratory conditions and lacks the corresponding industrial production conditions, we believe that discussing the cost at this stage is not significant. Therefore, no relevant discussion on cost has been included in this article. 

Once again, we appreciate your hard work and patience in the past. We hope the revised version meets your requirements and look forward to potential future collaborations in our future submissions.

Sincerely,

Jianchao Su