Broadband Vortex Beam Modulating System Based on Electrically Controlled Liquid Crystal Devices
Round 1
Reviewer 1 Report
The authors design and fabricate an electrically controlled LC q-plate and an LC broadband polarization grating, and realize the generation and modulation of "broadband" vortex beams. The paper has reliable methods in device design and processing, and has particular reference significance for the application of electrically controlled vortex beams in specific scenarios. This paper is generally interesting, but some of the content in the article still needs to be improved and modified before considering publication. See details as follow:
1. The term 'broadband' in the title seems unclear, and the expression of broadband vortex light can easily lead to misunderstandings. From the results of the paper, it can be seen that the system designed by the authors is a system that can tune and generate vortex beams in the range of 532-632.8nm.
2. The description of the experimental results is not very clear. For example, how was the measurement of the “vortex part” achieved in Figure 5, and why were the results at 532 and 632.8nm spatially separated? If measured separately, it should be clearly described and explained, otherwise, it may be confused with the subsequent results.
3. The intensity distribution of the beam was measured experimentally. In Figure 5, how is the normalized intensity achieved, and based on what is the maximum value of the normalized intensity? Figures 5 (b) and (c) do not show a normalized light intensity of 1.
Other opinions:
1. Formula (1) can easily lead to misunderstandings that it is a fraction;
2. Formulas (2) and (6) should provide references;
3. Is the delta n of line 87 related to wavelength? From the final result, it should be related to wavelength;
4. The x and p in formula (6) should be explained;
5. The expression of "The experimental setup of the broadband vortex beams generator" in the line 168 is inconsistent with the expression in Figure 4.
6. the line 187, when ->When;
Pay more attention to consistency in description and fluency in writing.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Authors proposed and implemented experimentally a modulating system for broadband vortex beams based on electrically-controlled liquid crystal devices that contains an electrically-controlled q-plate and an LC broadband polarization grating. The solution to the broadband modulation problem is quite original, and the article could be recommended for publication, but I was surprised by a weak justification of their research, which can be filled up by responding to my comments
[1] Although the authors touch upon an important problem, for some reason they ignore well-developed methods, e.g.., in articles DOI:10.1088/2040-8978/19/1/013001, DOI:10.1038/s41467-021-22462-z, DOI:10.1038/s41598-017-07437-9
[2] Generally speaking, this journal is intended for a wide range of readers, so the use of special technical terminology causes the reader to reject the article rather than the desire to get acquainted with it. What do the authors mean by employing the term “broadband modulation”? Modulation of quasi-monochromatic light or monochromatic light, but in different spectral regions? I recommend that the authors consider this issue using the example of a standard method using a single SIM device in the article DOI:10.1364/OE.25.025696, and only after that set the task of their research
A few more special questions
[3] Figure 1 shows two beams passing through the QWD at different angles. The question is, with what accuracy is it necessary to establish the relative positions of the PRS, MR, QWD and Sample in order to obtain two mutually orthogonal circular polarizations? What measurement error is allowed?
[4] . Specify the sensor model for measuring the light intensity
[5] What polarization states can be obtained with the Q-plate-broadband PG system? Is it possible to modulate higher orders of the mode polarization states using the experimental setup in Figure 4?
Authors proposed and implemented experimentally a modulating system for broadband vortex beams based on electrically-controlled liquid crystal devices that contains an electrically-controlled q-plate and an LC broadband polarization grating. The solution to the broadband modulation problem is quite original, and the article could be recommended for publication, but I was surprised by a weak justification of their research, which can be filled up by responding to my comments
[1] Although the authors touch upon an important problem, for some reason they ignore well-developed methods, e.g.., in articles DOI:10.1088/2040-8978/19/1/013001, DOI:10.1038/s41467-021-22462-z, DOI:10.1038/s41598-017-07437-9
[2] Generally speaking, this journal is intended for a wide range of readers, so the use of special technical terminology causes the reader to reject the article rather than the desire to get acquainted with it. What do the authors mean by employing the term “broadband modulation”? Modulation of quasi-monochromatic light or monochromatic light, but in different spectral regions? I recommend that the authors consider this issue using the example of a standard method using a single SIM device in the article DOI:10.1364/OE.25.025696, and only after that set the task of their research
A few more special questions
[3] Figure 1 shows two beams passing through the QWD at different angles. The question is, with what accuracy is it necessary to establish the relative positions of the PRS, MR, QWD and Sample in order to obtain two mutually orthogonal circular polarizations? What measurement error is allowed?
[4] . Specify the sensor model for measuring the light intensity
[5] What polarization states can be obtained with the Q-plate-broadband PG system? Is it possible to modulate higher orders of the mode polarization states using the experimental setup in Figure 4?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The authors proposed a broadband vortex beams modulating system based on electrically-controlled LC device. The system enables pure vortex-phase modulation within a wide spectral range in the visible spectrum and electrically-control on the output beam intensity of the vortex and Gaussian components. The research content of this paper is worth studying. There are some questions that need to be resolved before agreeing to its publication.
1. The authors stated “the maximal diffraction efficiency 159 was 97.63%” in the line 158 in page 5. How did the authors get this efficiency?
2. Is the intensity distribution in Figure 3d saturated? Or did the author make it look that way on purpose?
3. The authors showed the vortex part and output beam in Figure 5. What principle is the generated vortex part based on? Phase singularity or polarization singularity? The paper lacks the corresponding theoretical support.
4. Several related references about metasurface and vortex beams are highly suggested, e.g.,
(1) Laser & Photonics Reviews 2022, 2200236. https://doi.org/10.1002/lpor.202200236.
(2) SCIENCE CHINA Physics, Mechanics & Astronomy, 2021, 64(11), 114212.
The expression of English in the paper needs to be significantly improved.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
In this manuscript, the authors propose a broadband vortex beam modulating system based on electrically-controlled liquid crystal devices. The system integrates electrically-controlled LC q-plates and LC broadband polarization grating as crucial components, enabling pure vortex phase modulation within a wide range of the visible spectrum. Additionally, the system offers electrical control over the intensity of both vortex and Gaussian components of the optical beam. This work is promising in fields such as optical communications, laser processing, high-density optical storage, high-resolution imaging, and quantum technologies. Thus, I recommend it to publish in Photonics. Some comments are listed as follows for the authors to improve the manuscript.
1. It is recommended that the authors provide additional experimental details and expand upon the background information in the introduction. This would contribute to a comprehensive understanding of the study and its context.
2. The size of the intensity labels in Figure 5(c) appears to be too small. I suggest enlarging the labels to ensure better visibility and clarity.
3. In the title of the article, "Broadband vortex beams" is used as a modifier for "modulating system." However, it is worth considering whether "vortex beams" should be in the singular form ("vortex beam") to accurately reflect the nature and characteristics of the system. Kindly provide further explanation regarding the rationale behind the choice of using the singular form and its implications. This clarification is essential to ensure the title effectively conveys precise and unambiguous information.
4. In the theoretical part, it is strange that the authors presented their formulas without citing any reference. This basic theory is well known and can be easily found in many published papers.
5. The authors may consider citing relevant references about the generation of vortex e.g., Crystals, 10, 882 (2020); Appl. Phys. Lett. 118, 151102 (2021); Adv. Optical Mater. 10, 2201088 (2022).
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 3 Report
The author has addressed my earlier doubts and agreed to publish.
minor editing
