Optimal Control of Passive Cascaded Liquid Crystal Polarization Gratings

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

Thank you for your decision and constructive comments on my manuscript.
We have carefully considered the reviewers' suggestions and made some changes.
We tried our best to improve and made some revisions to the manuscript.

Author Response File: Author Response.pdf

Reviewer 2 Report

See the attached file

Comments for author File: Comments.pdf

Author Response

Dear reviewer:

Thank you for your decision and constructive comments on my manuscript. We have carefully considered the suggestion of Reviewer and make some changes. We have tried our best to improve and made some changes in the manuscript.

The yellow part that has been revised according to your comments.

Revision notes, point-to-point, and given as follows:

Page 1:

The references section has been improved.

The definition of “The orthogonal cascade polarization grating's diffraction efficiency” is supplemented.

add a reference and remove the Researcher name.

(Tan L, Ho J Y, Kwok H S. Extended Jones matrix method for oblique incidence study of polarization gratings[J]. Applied physics letters, 2012, 101(5): 051107.)

Page2:

“molecular director” instead of “The liquid crystal molecule vector”

Replaced Figure 1. Structure of a monolithic LCPG.

Line 75, add a space after ±1.

η_m is the m-class diffraction efficiency, S₃^’ = S₃/S₀ is the normalized Stokes parameter, Δn is the birefringence of liquid crystal, d is the thickness of liquid crystal layer, and λ is the wavelength of incident light, from equation (2) it can be seen that the liquid crystal polarization grating has only three diffraction stages: 0 and ±1, the intensity distribution between the diffraction stages, depending on the phase delay δ and incident polarization.

Page3:

Supplementary explanation “It is theoretically possible to achieve a single stage with a diffraction efficiency of 100%” but experimentally it is not.

add a reference (Tan L, Ho J Y, Kwok H S. Extended Jones matrix method for oblique incidence study of polarization gratings[J]. Applied physics letters, 2012, 101(5): 051107.)

In fact, after design optimization and process improvement, the diffraction efficiency of the 0 ° beam into the monolithic polarization grating can reach 97%.

Page5:

Thanks for your careful checks. We are sorry for our carelessness. Based on your comment, we have made the corrections to make the n₀ replaced n0 in line 145.

We sincerely appreciate the valuable comments. We have checked the literature carefully and added following references:

1) Lev M. Blinov “Structure and Properties of Liquid Crystals”, Ed. Springer Dordrecht, ISBN 978-

90-481-8828-4, https://doi.org/10.1007/978-90-481-8829-1

2) Tan L, Ho J Y, Kwok H S. Extended Jones matrix method for oblique incidence study of polarization gratings[J]. Applied physics letters, 2012, 101(5): 051107.

  We appreciate for Reviewers’ warm work earnestly, and hope the correction will meet with approval. Once again, thank you very much for your comments and suggestions.

Round 2

Reviewer 1 Report

Below I outline specific examples. I will give reference to the lines in the revised version that contains old and new text.

1. Problems with formulas 

1.1. Formula (1) presents components of LC director (or optical axis) rather than the components of refractive index.

 1.2. Formula (5) for S3 is rather strange and it is not explained how it was derived. Also, no corresponding reference is given. Accordingly, the next formula (6) is under doubt. 

1.3. The fraction in formula (10) corresponds to n(eff) rather than a difference (n(eff) - no) that should be presented in this formula of phase. The derivation given by author in supplementary file is incorrect. 

1.4. Obtaining the formula (11) is not explained and/or corresponding reference is not given. Accordingly, the derivative formula (13) is under doubt. 

1.5. Formula (15) is actually same as (9) but introduced angle omega is totally different from phi presented in (9). There are many confusions of this type. The authors introduced big number of parameters and sometimes it is very difficult to understand the difference between certain parameters.  

1.6. The Snell's law formulas (14) and next (14) (??) consider angles sigma, alpha and betta, which are poorly defined and not shown in Fig. 6a. or 6b. Are (a) and (b) different projections of the same sample? It is strange that the angle of incidence in fig. (a) is marked zeta, while in fig (b) - phi. Figure (a) is not good enough; it does not clearly show the path of the light beam and corresponding angles in air and in liquid crystal. 

1.7. Line 135. The calculation 2 × 40 °/1.25 °=64 should be explained.

2. The text is very difficult to read.

2.1. Poor English and poor editing. The examples:

lines 42-49. This sentence is too large and unclear. It should be divided in pieces. 

Lines 95-100. The text was inserted twice. 

Lines 107-110. Hard to read. It should be split in pieces; one sentence - one thought.  

2.2. The symbol confusion.

In formulas (3), (4) the authors denote the phase with the symbol phy, while later demote it by symbol delta. Symbol phi is also used to denote the LC rotation angle, Fig. 5, formulas (7), (8)... 

2.3. Terminology

- The terms "layer control coefficient" and "slice control coefficient", if they are important, should be clearly explained, possibly by giving corresponding figure and formulas. The meaning of "layer", "slice", and "floor" (Table 1, confusing term!) should be clearly defined. The definition like "The plate control coefficient mainly indicates that the deflection angle of a liquid crystal adjustable half wave plate in the layer is positive and negative, and the values are - 0.5 and +0.5" is not acceptable, because it does not give a clear and unambiguous interpretation of this term, and calculation of the presented numbers.

- phase delayer should be replaced by commonly accepted term phase retarder. The phrase like "phase delayer phase delay theory" should be "phase retarder theory", the phrase "The xoy plane is parallel to the phase delayer method plane" should be replaced with "The xoy plane is parallel to the plane of the phase retarder" and so forth... I have a lot of other comments of this type...

Because the part related to calculations contains incorrect and controversial formulas and the experimental part is small and poorly informative, the scientific value of this work still raises big questions for me.

So, I believe that this version of the manuscript is also far from an acceptable version for publication in a journal that values its reputation.

Sincerely,

Oleg Yaroshchuk

Author Response

Dear reviewer:

Thank you for your decision and constructive comments on my manuscript. We have carefully considered the suggestion of Reviewer, We have made extensive corrections to our previous draft, the detailed corrections are listed below.

1.

1.1 Thanks for your careful checks. We are sorry for our carelessness. Based on your comment, we have made the corrections to make the LC director replaced refractive index in formula (1).

1.2 S₃^’ is the normalized Stokes parameter.

1.3 From vertical equations (8) and (9), the phase delay LCVR quantity can be expressed as

The derivation process is as follows:

1.4 A= ;B=

Since the fitting results are approximate for A and B, we can be represented by A as B.

1.5 Since the e-light refractive index is used, Formula 15 is given here.

1.6 Figure 6 and related contents have been modified.

1.7 In order to achieve 1.25 ° resolution and ± 40 ° angle deflection control, a total of 5 lay-ers of LCPG.

 

2.1

This paragraph mainly describes the current research situation and the significance of this study.

 In line 97-100, Li Tan's research is mentioned again. Here we want to show that he uses a new structure to improve the diffraction efficiency in his research.

2.2 Thanks for your careful checks. We are sorry for our carelessness. Based on your comment, we adjusted for the symbols used.

2.3 Cascaded LCPGs combine multiple LCPG layers in series. Each LCPG layer can achieve a fixed angle of deflection. Multilayer LCPGs can achieve deflection in a large angle range. The combination forms include binary, quasi binary and ternary. The most common combination form is binary.

We carefully checked the technical terms in the text and replaced them to make the text more professional.

 

Sincerely,

Huan Qin