Cascade Analysis Method of Multilayer Optical Films Structure Based on Two Port Transmission Line Theory
Round 1
Reviewer 1 Report
Two-port transmission line theory-based cascading calculation method was proposed to avoid overlong simulation time and lumbersome running load due to the huge grid divisions due to thickness difference between the substrate and the incident wavelength. In general, the topic is interesting. However, several major concerns need to be addressed before its publication.
Major concerns:
1. For the case with only transparent substrate or only metallic film, the coincidence is good between the simulations and calculations in the region of 60-100 THz. But in 120-750 THz, there is some discrepancy between the simulated and calculated results. Why? The coincidence is even worse for the case with transparent substrate and metal film. Why?
2. On page 6, paraph 2, the authors stated that “the thicker the transparent substrate is, the higher the degree of coincidence is.” However, from figure 6 (b), the coincidence is also bad for the thicker substrate.
3. In figure 7 (b), the author can improve the calculated results with the measured parameters.
Minor concerns:
1. The language of the manuscript should be improved.
2. The clarity for Fig. 7 (a) should be improved. The notation should be in English as well.
Author Response
Response to Reviewer 1 Comments
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 red part that has been revised according to your comments. Revision notes, point-to-point, are given as follows:
Point 1: For the case with only transparent substrate or only metallic film, the coincidence is good between the simulations and calculations in the region of 60-100 THz. But in 120-750 THz, there is some discrepancy between the simulated and calculated results. Why? The coincidence is even worse for the case with transparent substrate and metal film. Why?
Response 1:
As shown in Figs. 3, 4 and 5, when the response frequency is 120-750 THz, the results of direct simulation and cascade calculation are completely consistent in the case of single transparent substrate cascade calculation. However, in the case of single metal film cascade calculation or metal film and transparent substrate cascade calculation, no matter the response frequency is 60-100 THz or 120-750 THz, the results of cascade calculation must be fitted to achieve a high degree of coincidence.
The reasons for this result are as follows: (1) When metal materials are involved in the calculation, as the number of free electrons in the metal materials increases, the number of resonant electrons participating in the excitation of surface plasmons increases, which will lead to more changes in the transmission peak amplitude and position of the response band. This is slightly inconsistent in the direct simulation of the software. (2) When the response frequency increases, that is, the wavelength is shorter, the number of electrons participating in resonance will also increase. In a narrow frequency range, the distribution of transmission peaks is more complex and the fluctuation will be greater. Therefore, we use fitting values to describe and compare. The result reflects that the result of direct simulation can be better matched after fitting. This point is also described and analyzed by Formulas 11-13, and some parameters that affect it are indicated.
Based on the above analysis, we can conclude that when only transparent substrates are used for cascading calculation, the cascading calculation can achieve a better solution regardless of the response frequency and substrate thickness. When metal materials are involved in the calculation, due to the higher coupling strength of free electrons, we need to fit the curve to achieve basic consistency. It is worth noting that the fitting will not have a significant impact on the actual response.
Point 2: On page 6, paraph 2, the authors stated that “the thicker the transparent substrate is, the higher the degree of coincidence is.” However, from figure 6 (b), the coincidence is also bad for the thicker substrate.
Response 2:
In Fig. 6, we show the transmission distribution of cascaded transparent substrates with different thicknesses and metal films with the same thickness. By comparing Figs. 6(a) and 6(b), when the transparent substrate is thin (0.1um thick), the transmittance distribution will generally decrease by about 0.15. When the thickness is increased to 1 um, although there is a large error between the transmission distribution after cascade calculation and the direct simulation results. It is worth noting that the cascade calculation results can achieve a high degree of coincidence with the direct simulation results after fitting. The purpose of fitting is to make the curve of cascade calculation result more smooth, and will not have a greater impact on the actual results. Therefore, in the article, we come to the conclusion that the thicker the transparent substrate is, the higher the coincidence of the results of the cascade calculation fitting is.
In order to avoid misunderstanding, we redefine it in the article: In other words, the thicker the transparent substrate is, the higher the coincidence degree is in the case of cascaded calculation fitting.
Point 3: In fig. 7(b), the author can improve the calculated results with the measured parameters.
Response 3:
The results shown in Fig. 7(b) are measured according to the actual parameters shown in Fig. 7(a). It is worth noting that the parameters used in the experiment in Fig. 7(a) are obtained after several parameter optimizations in the previous chapters and sections. Therefore, we show three results in Fig. 7(b), including actual measurement, cascade calculation and fitting calculation. The low peak amplitude of the final measurement results is due to the factors such as the precision of the lithography machine, the time of coating, and the speed of glue leveling in the experiment. In the subsequent experiments, we can adjust the experimental conditions to improve the accuracy of the device to meet higher requirements.
Point 4: The language of the manuscript should be improved.
Response 4:
We apologize for the poor language of our manuscript. We worked on the manuscript for a long time and the repeated addition and removal of sentences and sections obviously led to poor readability. We have now worked on both language and readability and have also involved native English speakers for language corrections. We really hope that the flow and language level have been substantially improved.
Point 5: The clarity for Fig. 7(a) should be improved. The notation should be in English as well.
Response 5:
To solve the problem of low resolution in Fig. 7(a), we took photos of the periodic hole array structure again to improve its resolution. However, due to the small size of the structure, the resolution ratio of measuring instrument used cannot be magnified to the required multiple, which will lead to the overall illusion of the picture to some extent.
In order to make the structural dimension data more precise, we use the built-in marking function in the measuring instrument to mark the size. It is worth noting that the contents marked in the figure are the notes attached to the instrument, which cannot be marked in English.
In addition, we have revised the grammar of the full article.
Thanks again for your time and valuable suggestions, and the revised part of the article has been highlighted.
Author Response File: 
Author Response.docx
Reviewer 2 Report
The introduction part can brief more about what people are doing in this area of research work and what you’re doing differently from others; research should reflect.
In line 11 and 12: micro/nano lithography replace with micro- and nano-lithography
In line 12, 13 and 14: In this article, the giant-sized thickness transparent substrate and the metal film were uniformly sliced, and then use the CST software to simulate the sliced substrate and the metal film to obtain the optical response parameters of their slices replace with In this article, we cut the giant sized thickness of the transparent substrate and the metal film were uniformly sliced. Then, we used the CST software to simulate the sliced substrate and the metal film to get the optical response parameters for each slice.
In line 20: which provides an effective idea and solution replace with which provides a practical idea and solution
Likewise please check the whole manuscript grammatical errors.
Author Response
Response to Reviewer 2 Comments
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 red part that has been revised according to your comments. Revision notes, point-to-point, are given as follows:
Point 1: The introduction part can brief more about what people are doing in this area of research work and what you’re doing differently from others; research should reflect.
Response 1:
In the Introduction, we first introduced the impact of micro nano technology. It is included in super surfaces, terahertz sensors, MEMS devices, micro-optical devices and micro fluids. At the same time, we cited our previous work and the achievements of other researchers to introduce the process preparation of micro nano structures and their tuning role in the optical band in detail.
It is worth noting that in the current mainstream research work, there are not many achievements on the treatment of thick substrate, especially the application of slicing and cascading methods proposed by us. Therefore, in the Introduction, we only introduce the problems existing in the current thick substrate processing and the theoretical basis for using the equivalent-circuit model to solve the slicing of thick substrates.
The revised content has been marked in red.
Point 2: In line 11 and 12: micro/nano lithography replace with micro- and nano-lithography.
Response 2:
The modified content has been marked in the corresponding position in the article.
Point 3: In line 12, 13 and 14: In this article, the giant-sized thickness transparent substrate and the metal film were uniformly sliced, and then use the CST software to simulate the sliced substrate and the metal film to obtain the optical response parameters of their slices replace with In this article, we cut the giant sized thickness of the transparent substrate and the metal film were uniformly sliced. Then, we used the CST software to simulate the sliced substrate and the metal film to get the optical response parameters for each slice.
Response 3:
The modified content has been marked in the corresponding position in the article.
Point 4: In line 20: which provides an effective idea and solution replace with which provides a practical idea and solution.
Response 4:
The modified content has been marked in the corresponding position in the article.
In addition, we have revised the grammar of the full article.
Thanks again for your time and valuable suggestions, and the revised part of the article has been highlighted.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
My concerns have been addressed.
