Designing and Tailoring Optical Properties: Theory and Simulation of Photonic Band Gaps in Photonic Materials

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this work, a theoretical work is presented for predicting the PMMA and PS based photonic crystals. The work presentation is good and could be helpful for future works. But, before publication of article I would like to get clarity on the given points.

1.       What is the importance of f_sphere.

2.       In line 55, authors mentioned the role of PC in environmental protection, how, explain.

3.       Authors should use abbreviations properly. For instance, AM being used frequently but not detailed.

4.       In line 91, authors have mentioned the passage of other waves, what are the other waves, please mention.

5.       In line 93, authors mentioned the incident angle of light is perpendicular and used angle is 0. It should need to be checked. Whether it is 0 or perpendicular.

6.       On what basis, different diameters and wavelengths are considered for presenting Fig. 2.

7.       It is suggested to disclose all necessary simulation parameters used to research the similar structure in future.

 

Comments on the Quality of English Language

authors are suggested to look for grammatical mistakes throughout the manuscript.

Author Response

Dear Reviewer:

Thank you very much for reviewing our manuscript “Designing and Tailoring Optical Properties: Theory and Simulation of Photonic Band Gaps in Photonic Materials” (Manuscript ID: photonics-2802786) again. Your valuable comments and suggestions will greatly help us to improve our manuscript. We have carefully revised our manuscript according to your suggestions, and point-by-point answered questions. In the revised manuscript, following important improvements have been made:

 

1. What is the importance of f _sphere.

Thanks for your kind suggestion. The “f _sphere” is the microsphere volume fraction of the PCs, which affects the effective refractive index, a parameter in Bragg's diffraction law, and further affects the photonic band gap of photonic crystals. Therefore, the effect of “f _sphere” was considered, and the microspheres volume fraction of the photonic crystals in this study was 74%. (Line 46)

2. In line 55, authors mentioned the role of PC in environmental protection, how, explain.

Thanks for your kind suggestion. The unique optical properties of the photonic crystals can detect pollutants, and their porous structure and high specific surface area can be conducive to catalyze the degradation of pollutants, therefore, the photonic crystals can be used in environmental protection ^[1-4]. The above articles have been cited (citation 14-17) for exploring the role of PC in environmental protection. (Line 55)

[1]   Li, X.; Zhen, X.; Meng, S.; Xian, J.; Shao, Y.; Fu, X.; Li, D., Structuring β-Ga2O3 Photonic Crystal Photocatalyst for Efficient Degradation of Organic Pollutants. Environmental Science & Technology 2013, 47 (17), 9911-9917.

[2] Wu, Y.; Li, X.; Liu, C.; Chang, X.; Hu, X., Studies on the active radicals in synthesized inverse opal photonic crystal and its effect on photocatalytic removal of organic pollutants. Journal of Molecular Liquids 2020, 320, 114414.

[3] Yu, J.; Caravaca, A.; Guillard, C.; Vernoux, P.; Zhou, L.; Wang, L.; Lei, J.; Zhang, J.; Liu, Y. Carbon Nitride Quantum Dots Modified TiO2 Inverse Opal Photonic Crystal for Solving Indoor VOCs Pollution Catalysts [Online], 2021.

[4] Wu, Y.; Ren, S.; Chang, X.; Hu, J.; Wang, X., Effect of the combination of inverse opal photon superficial areaic crystal and heterojunction on active free radicals and its effect on the mechanism of photocatalytic removal of organic pollutants. Ceramics International 2023, 49 (16), 27107-27116.

3. Authors should use abbreviations properly. For instance, AM being used frequently but not detailed.

Thanks for your kind suggestion. We have corrected the abbreviation. The “PMMA” was changed to “polymethyl methacrylate (PMMA)”, The “PS” was changed to “polymethyl methacrylate (PS)” and the “AM” was changed to “acrylamide (AM)”. (Line 11,14 and 234)

4. In line 91, authors have mentioned the passage of other waves, what are the other waves, please mention.

Thanks for your kind suggestion. We have changed “The origin of the photonic band gap (PBG) in the photonic crystals (PCs) lies in their periodic structures. As light propagates through these structures with varying media, a periodic potential field, often referred to as the effective refractive index (n_eff), is generated. This field acts as a barrier for certain electromagnetic waves, preventing their propagation, while enabling the passage of others as shown in Figure 1a and Figure 1b.” to “The origin of the photonic band gap (PBG) in the photonic crystals (PCs) lies in their periodic structures. As light propagates through these structures with varying media in the form of electromagnetic waves, a periodic potential field, often referred to as the effective refractive index (n_eff), is generated. This field acts as a barrier for certain electromagnetic waves, which was in the photonic band gap (PBG), and preventing their propagation, while enabling the passage of the electromagnetic waves that are not in the PBG pass through as shown in Figure 1a and Figure 1b”. (Line 154 to 160)

5. In line 93, authors mentioned the incident angle of light is perpendicular and used angle is 0. It should need to be checked. Whether it is 0 or perpendicular.

Thanks for your kind suggestion. We have changed “when the light is incident perpendicular” to “the angle between the incident light and the normal line of the photonic crystals interface is 0 (θ = 0)”. (Line 162 and 163)

6. On what basis, different diameters and wavelengths are considered for presenting Fig. 2.

Thanks for your kind suggestion. According to Bragg's diffraction law, the microsphere diameter has a significant effect on the PBG of the photonic crystal, and the position of the PBG is positively correlated with the microsphere diameter. Based on the research basis of our laboratory, the PMMA microspheres with different diameters was prepared and characterized their optical properties, which can be used to guide the preparation of microspheres and photonic crystals with specific reflective peaks.

7. It is suggested to disclose all necessary simulation parameters used to research the similar structure in future.

Thanks for your kind suggestion. The necessary simulation parameters include the crystal form, the microsphere diameter, the refractive index of the dielectric and the size of the photonic crystal element, where the crystal form uses Rsoft's built-in FCC lattice, the microsphere diameter was measured by SEM, and the refractive index is determined by the dielectric type. The size of the photonic crystal element was  times of the microsphere diameter. (Line 146 and 151)

 

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Reviewer comments:

In this paper, the photonic band gap (PBG) of PMMA and PS photonic crystals was predicted using theoretical calculations and numerical simulations.  

 

The comments are:

1. Many abbreviations are used without defining them.

2.  The font of the formulas is too large. And it’s not clear why there is a need for a dotted line before the number, indicating the formula number.

3. "n_air = 1 is the refractive index of air". Air does not have a refractive index of 1, under different conditions this value will vary with temperature, composition of air and many other parameters. Therefore, it is better to use the formulation of a void between molecules in a crystal lattice and then the refractive index of vacuum (void), , is better suited.

4. Line 94, formula 4. A rather obvious formula, it is enough to specify that θ = 0.

5. line 96-98, formulas 5-7. They are not self-sufficient formulas that need to be highlighted separately. It seems to me that it will be better if you simply write them down in the text, with a link using equation 1. For example, the authors have already made this design option in lines 113-114.

6. Line 179, equation 10, the equation is not transformed, it looks more concise in the transformed form. Transformed form: . Sin is also removed, since it is equal to 0 in Equation 4.

7. The authors of the paper compare the values obtained by the Bragg formula with experimental results and numerical values obtained from Rsoft. However, what is the novelty of this approach? Perhaps more attention should be paid to the difference between the chosen model and the calculation using the Bragg formula.

 

In conclusion, I believe this article is not appropriate for Gels. It is more suitable for Photonics of MDPI

Comments on the Quality of English Language

In my opinion, the English of the article is not bad.

Author Response

Dear Reviewer:

Thank you very much for reviewing our manuscript “Designing and Tailoring Optical Properties: Theory and Simulation of Photonic Band Gaps in Photonic Materials” (Manuscript ID: photonics-2802786) again. Your valuable comments and suggestions will greatly help us to improve our manuscript. We have carefully revised our manuscript according to your suggestions, and point-by-point answered questions. In the revised manuscript, following important improvements have been made:

 

1. Many abbreviations are used without defining them.

Thanks for your kind suggestion. We have corrected the abbreviation. The “PMMA” was changed to “polymethyl methacrylate (PMMA)”, The “PS” was changed to “polymethyl methacrylate (PS)” and the “AM” was changed to “acrylamide (AM)”. (Line 11,14 and 234)

2. The font of the formulas is too large. And it’s not clear why there is a need for a dotted line before the number, indicating the formula number.

Thanks for your kind suggestion. We've adjusted the formula font and removed the dotted lines from the formula.

3. "nair = 1 is the refractive index of air". Air does not have a refractive index of 1, under different conditions this value will vary with temperature, composition of air and many other parameters. Therefore, it is better to use the formulation of a void between molecules in a crystal lattice and then the refractive index of vacuum (void), is better suited.

Thanks for your kind suggestion. The “n_air =1 is the refractive index of air” have been changed to “n_air is the refractive index of air and was generally considered to be 1”. (Line 45)

4. Line 94, formula 4. A rather obvious formula, it is enough to specify that θ = 0.

Thanks for your kind suggestion. We have changed “when the light is incident perpendicular” to “the angle between the incident light and the normal line of the photonic crystals interface is 0 (θ = 0)”. (Line 162, 163)

5. line 96-98, formulas 5-7. They are not self-sufficient formulas that need to be highlighted separately. It seems to me that it will be better if you simply write them down in the text, with a link using equation 1. For example, the authors have already made this design option in lines 113-114.

Thanks for your kind suggestion. We have simply written the formulas 5-7, which was “The eq. 2, eq.3 and eq.4 are substituted into eq.1 to obtain the linear relationship between the theoretical reflectance peaks and diameters of SiO₂ PCs, PMMA PCs and PS PCs, which were λ_SiO2 = 2.3022 D (n_SiO2 =1.46), λ_PMMA = 2.3495 D (n_PMMA =1.49), and λ_PS = 2.5072 D (n_PS =1.59)”. (Line 165 to 168).

6. Line 179, equation 10, the equation is not transformed, it looks more concise in the transformed form. Transformed form: Sin is also removed, since it is equal to 0 in Equation 4.

Thanks for your kind suggestion. The equation

 

had been transformed to

 

(Line 250)

7. The authors of the paper compare the values obtained by the Bragg formula with experimental results and numerical values obtained from Rsoft. However, what is the novelty of this approach? Perhaps more attention should be paid to the difference between the chosen model and the calculation using the Bragg formula.

Thanks for your kind suggestion. The combination of theoretical calculation and numerical simulation provides better visual data, accurately describes the essential problem, and provides reliable theoretical support and guidance for experiments, which will benefit to promote research process. The theoretical calculations and numerical simulation systems in this paper can accurately and reliably predict the optical properties of photonic materials and evaluating their response effects, which provided a simple and fast solution for the design and fabrication of photonic materials. “Theoretical calculations can accurately describe problems and grasp their essences, however, the limitations of came from research conditions make it more suitable for qualitative analysis. Numerical simulations can support and supplement the results of theoretical research, which can visualize the results in more ways and enhance the readability of the research results” had been added to indicate the difference between theoretical calculations and numerical simulations (line 62-66). Besides, “and the applied structural model of the numerical simulation was consistent with the FCC lattice in Bragg's diffraction law” was added in line 77 to 79.

In conclusion, I believe this article is not appropriate for Gels. It is more suitable for Photonics of MDPI

Thanks for your kind suggestion. We had transferred the article to the Photonics.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have improved the manuscript, its revised version is more accurately, transparently, and appropriately written. For the most part the paper is of a suitable standard, making the methods, results, and corresponding pictures, reasonably easy to follow. Thus, I have no any objection against the publication of the revised manuscript in the Photonics.