Investigation of Quadrate Fresnel Zone Plates Fabricated by Femtosecond Laser Direct Writing

Round 1

Reviewer 1 Report

In this article the authors explore different design of Fresnel zone plate. They aboard 3 classical Fresnel zone plates with quadratic, lineal and orthogonal outer shapes and several phase-shift Fresnel Zone plate (quadratic, rectangular…). The authors also aim to specify the fabrication process, but I found very vague the description. Although I found very useful and interesting the topic, I found that the structure of the paper is complicated due to the large number of optics and parameters studied. I recommend include tables for summarizing the results, quantify more often the results, re-structure the section 2 in sub-sections and improve the captions of the figures, before its publications.

Some questions that I would like the authors to address are:

1.       Why did the author choose femtosecond laser for the fabrication? Are there advantages respect to the other methods? What the main difference with lithography?

2.       An individual description of the differences of the zone plates would be necessary, including, applications, or ideal wavelengths? Do all the FZP use identical parameters, i.e., rn, number of zones?

3.       I would like to see a comparison of the minimum focus size of each FZP including classical ones. Are there also changes between focal lengths in the position of the diffractive focal lengths?

4.       Can one obtain from the graphics equations to, for instance, self-calculate the ideal number of zones?

5.       If efficiency is mentioned in the text (for example for Fig. 7), could the authors include also a graph or a table to compare numbers and not only have a qualitative analysis?

6.       In Line 248, the authors said that the diffraction pattern is consistent with the experimental one. Could they develop what they mean? If the only refer that both patterns assembled, could they include in the figure intensity and profile? Specially, I think a profile will show that they do not assemble perfectly.  The same affect to figure 11.

7.       Respect to the difference between simulations and experiments, could the author comment why? May be fabrication defects? Resolution of the simulations? …

8.       From my point of view the conclusions addressed that circular zone plates are very problematic, but in the introduction or in the simulations the reason for the authors to think that is mentioned only vaguely. Base on the broad use of circular zone plates I do not believe they need to be designed improved. However, for specific applications: beam splitting, lineal focus, etc… the research of new designs is very useful.

Author Response

Dear reviewer：
Thank you for your professional opinions on the paper, which greatly guide my work. According to your suggestion, we have rewritten and optimized the whole article. Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

 

The manuscript investigates Fresnel zones by femtosecond laser direct writing. The theoretical, simulation, and experimental understanding provided could be interesting to the optics community. The manuscript could be considered after the following minor revisions are made.

11. The introduction could be strengthened. Please clarify the motivation and possible end applications of this work.

22. Newer references (from 2022) should also be added and discussed. 

3 In experimental methods, details and features of the software versions and of the optical microscope could be added.

4.      The manuscript has multiple sentence formation errors, which should be corrected

 

Author Response

Dear reviewer：
Thank you for your professional opinions on the paper, which greatly guide my work. According to your suggestion, we have rewritten and optimized the whole article. Please see the attachment.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

I recommend the new version for its publication.