Effect of Lower-Level Relaxation on the Pulse Generation Performance of Q-Switched Nd:YAG Laser

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The report is appended in the PDF file.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

The english is fine in general.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

This study investigates the influence of lower-level relaxation on pulse distortion in Q-switched Nd:YAG lasers. While the experimental data and theoretical framework are technically sound, the manuscript fails to meet originality standards due to substantial overlap with the authors’ prior publication in a Chinese journal (Influence of energy level lifetime of Nd:YAG Q-switched laser on laser pulse performance[J]. Journal of Applied Optics, 2023, 44(6): 1236-1243. DOI: 10.5768/JAO202344.0610010). This presents academic ethical concerns and indicates a lack of innovation. Consequently, it is recommended that the manuscript be rejected.

Please find my comments and questions as follows:

1. Content Overlap:

The theoretical model (four-level rate equations), simulation approach (LELA vs. NLELA), and experimental results (e.g., tail peak energy ratios, pulse waveforms in Figures 3-5) are directly replicated from the authors’ Chinese-language paper (http://www.yygx.net/cn/article/doi/10.5768/JAO202344.0610010). Over 80% of the methodology and results mirror the prior publication without proper citation or justification.

2. Insufficient Novelty:

1) Marginal Incremental Contribution: The added discussion on longitudinal modes and expanded literature review (e.g., Siegman’s theory) remains superficial. The central findings such as the critical role of lower-level lifetime in pulse distortion are identical to those in the earlier work, offering no significant advancement in theory, methodology, or application.

2) Lack of Broader Implications: The study does not extend its conclusions to new laser systems (e.g., Nd:YVO₄), practical mitigation strategies, or industrial applications, limiting its relevance to the existing literature.

Comments on the Quality of English Language

The English should be further polished as some sentences are difficult to understand.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors,

I suggest careful addressing of the following comments.

1. Page 3, Line 100, correction of the value of ratio between the relaxation time of the upper vs. the lower level, should be done.
2. Page 3, Line 127, The LD output beam usually is characterized by high (few tens) M² values. The authors claim the output of their focused LD beam is nearly Gaussian which is not the case. Perhaps they should mention that they approximate the pump beam in their simulations with a Gaussian beam.
3. Page 4 line 128, the absorbing distance of the considered Nd:YAG medium could be given.
4. Page 4, reference for equation 4 should be added.
5. Page 4, Line 146 reference 27 does not exist. The correct reference should be added and included in the reference list if is needed.
6. Page 4, line 153, reference to be added to equation 6.
7. Page 5, line 188, add reference to the equation.
8. Page 190, in the equation V denotes the volume of laser crystal which contributes to the laser gain, in this case, the volume corresponding to absorption length of the crystal at pumping wavelength. Was this volume considered in the simulations?
9. The presentation of simulation algorithm could be improved.
10. The flow chart could be correlated better with the presentation of simulation algorithms in the main text if for example the steps numbers or appropriate evaluated parameters are mentioned and included in the flow chart. 
11. Different text font sizes are used in the main text for different equations. The valuated parameters are not aligned with the referring text. Editing errors should be removed.
12. Page 9, more details regarding the experimental set up and materials should be provided (the oscilloscope and photodiode specifications should be mentioned). 
13. What is the pump power at lasing threshold? How far from the laser threshold was the laser operated? Why the authors opted for their study for the pump powers values of 80, 90 and 100 W? 
14. They discuss actively Q switching of Nd:YAG laser. Could the authors comment regarding their approach for the Cr:YAG and passive Q-switching case?
15. Page 9, Figure 6, the image taken with the oscilloscope could be increased or better resolution should be used.

Comments on the Quality of English Language

 The English could be easily improved.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

the MS is fine for publication

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have addressed the questions.