Holographic Writing of Forked Diffraction Gratings on the Surface of a Chalcogenide Glass Semiconductor
, Vladimir V. Podlipnov 1,2 and Sergey V. Karpeev 1,2,*
Round 1
Reviewer 1 Report
The authors fabricated the forked diffraction gratings in semiconductors As2S3 and a-Se with selected incident polarizations. Also the vortex beams were generated with the fabricated gratings. I found this work is interesting and it can be published with the following comments addressed:
What is the reason to use the materials of semiconductors As2S3 and a-Se? What is the thickness of the film?
For the direct laser patterning, what is the laser used for the fabrication? Also what is the writing condition of the laser beam, in energy, time, etc. What is the writing resolution of the patterns in the current semiconductors As2S3 and a-Se.
Fig 5, what is the writing speed for the fork grating formation. What is the wavelength of the laser for Fig 6?
For outlook, some references can be cited in optical beam generation with holographic metasurface, such as Advanced Optical Materials, 6, 1701228 (2018). Scientific Reports, 9, 19656 (2019). Physical Review Applied, 11, 064059 (2019). Advanced Optical Materials, 6, 1701228 (2018).
Author Response
We are grateful to the reviewers for their valuable efforts. We have significantly rewritten the paper in response to their comments. English language has been revised throughout the whole paper. We added two versions of the paper the MS Word document, and the pdf with changes highlighted in yellow.
- What is the reason to use the materials of semiconductors As2S3 and a-Se? What is the thickness of the film?
Reply: Thank you for the comment. We have added a description of the selected material to the "Experimental" section.
“As2S3 and a-Se chalcogenide glass semiconductors described in these papers has an advantage over azopolymer-based materials [33, 34] in the formation of lattice structures. The initial material formed by spraying has high indicators of uniformity of structure, uniformity of thickness. At the same time, the technology of applying multilayer coatings can be carried out by standard industrial technologies for automated application of optical coatings. The use of two types of layers As2S3 and a-Se allows optically forming a microrelief without the use of etching. And the use of a large number of thin alternating As2S3 and a-Se nanolayers makes it possible to increase the degree of heaving of the material with a small response in each pair of layers. This technology is described and studied in detail in earlier works [38]. The optimal parameters of the thickness of the layers were also selected. As in [38], we used a sample of 110 pairs of nanolayers with 9 nm As2S3 and 3 nm a-Se with a total thickness of 1.3 microns.”
- For the direct laser patterning, what is the laser used for the fabrication? Also what is the writing condition of the laser beam, in energy, time, etc. What is the writing resolution of the patterns in the current semiconductors As2S3 and a-Se.
Reply: Direct laser patterning was performed using a 532 nm, single-mode, linearly polarized laser. The duration of the writing time was 3 min, and the power density was 10 W/cm2.
We have added beam characteristics to the "Experimental" section.
- Fig 5, what is the writing speed for the fork grating formation. What is the wavelength of the laser for Fig 6?
Reply: The dynamics of direct laser patterning was not studied in this work.
The wavelength was the same as that used for holographic writing (532 nm).
We have added the wavelength to the manuscript.
- For outlook, some references can be cited in optical beam generation with holographic metasurface, such as Advanced Optical Materials, 6, 1701228 (2018). Scientific Reports, 9, 19656 (2019). Physical Review Applied, 11, 064059 (2019). Advanced Optical Materials, 6, 1701228 (2018).
Reply: Thank you for the comment. We have added the article to the References.
Reviewer 2 Report
Forked diffraction gratings are interesting and important for the development of advanced optical elements. The authors of this manuscript report a method for polarization holographic generation of forked diffraction gratings in a multilayer structure based on chalcogenide glass.
The manuscript could be considered for publication after some modifications.
It is not explained why the gratings are written on the multilayer. Whether you generate the multilayer yourself and in what way? What is the number of nanolayers and what is their period?
What is the intensity ratio of the reference and the vortex beams?
What is the height of the profile in the pictures 5a and 5b?
Explain in more detail how was the diffraction efficiency measured. Is the region with zero reference intensity excluded from the calculations?
Author Response
We are grateful to the reviewers for their valuable efforts. We have significantly rewritten the paper in response to their comments. English language has been revised throughout the whole paper. We added two versions of the paper the MS Word document, and the pdf with changes highlighted in yellow.
- It is not explained why the gratings are written on the multilayer. Whether you generate the multilayer yourself and in what way? What is the number of nanolayers and what is their period?
Reply: Thank you for the comment. We have added a description of the selected material to the "Experimental" section.
“As2S3 and a-Se chalcogenide glass semiconductors described in these papers has an advantage over azopolymer-based materials [33, 34] in the formation of lattice structures. The initial material formed by spraying has high indicators of uniformity of structure, uniformity of thickness. At the same time, the technology of applying multilayer coatings can be carried out by standard industrial technologies for automated application of optical coatings. The use of two types of layers As2S3 and a-Se allows optically forming a microrelief without the use of etching. And the use of a large number of thin alternating As2S3 and a-Se nanolayers makes it possible to increase the degree of heaving of the material with a small response in each pair of layers. This technology is described and studied in detail in earlier works [38]. The optimal parameters of the thickness of the layers were also selected. As in [38], we used a sample of 110 pairs of nanolayers with 9 nm As2S3 and 3 nm a-Se with a total thickness of 1.3 microns.”
- What is the intensity ratio of the reference and the vortex beams?
Reply: The non-polarizing beam splitters BS1 and BS2 have a 50:50 shoulder ratio. Losses when using a spiral phase plate are low.
We have added the intensity ratio to the manuscript.
- What is the height of the profile in the pictures 5a and 5b?
Reply: The height of the lattice formed by interference of beams with linear polarizations of +45° and -45° is 271 nm. The height of the lattice formed by interference of beams with circular polarization of left and right rotation is 115 nm.
We have added the height of the profile to the manuscript.
- Explain in more detail how was the diffraction efficiency measured. Is the region with zero reference intensity excluded from the calculations?
Reply: Measuring diffraction efficiency is not very difficult, so we did not give this description. However, such experiments, including on this material, have already been carried out and are described, for example, in the cited reference37 Achimova. However, when working with focused radiation, the use of a probing beam has difficulties, therefore, both recording and measurements were carried out on the image of the diffraction pattern in the camera. Thus, we understand exactly that we are covering exactly the recorded very small area with a lattice and nothing superfluous gets in. However, there are also errors in the analysis of the image and the interpretation of brightness in the image into intensity. We have added a description of the fact that the diffraction efficiency indicators we have obtained differ from real life in the text. Also, this method does not take into account the losses during the passage of the structure to the lumen, which can be up to 50% relative to the incident radiation.
Reviewer 3 Report
Vortex laser beams are currently attracting considerable attention of researchers due to a wide use of these beams in problems of atmospheric communication and optical manipulation. Vortex laser beams have been wide used in a variety of atmospheric communication and optical manipulation. The beams generated by the diffractive optical elements have a specific phase distribution; however, their production is a complex and expensive technical process. In the manuscript, the authors presented a method for the formation of forked diffraction gratings on the surface of a multilayer structure based on chalcogenide glass semiconductors As2S3 and a-Se. In order to study the direct holographic writing of diffraction gratings with a "forked" structure, the electric field components of the Gauss beam and the first-order vortex beam are calculated. The authors examined the parameters of vortex laser beams generated by the microrelief formed. The findings present in this work is interesting, however, I do have the following comments to make the manuscript more satisfactory.
1. The advantages of chalcogenide glass semiconductors should be further explained in the introduction.
2. The author should add some formulas calculate the components of the electric field upon interference of a Gaussian beam and a first-order vortex beam.
3. The format of some references is not uniform.
Author Response
We are grateful to the reviewers for their valuable efforts. We have significantly rewritten the paper in response to their comments. English language has been revised throughout the whole paper. We added two versions of the paper the MS Word document, and the pdf with changes highlighted in yellow.
- The advantages of chalcogenide glass semiconductors should be further explained in the introduction.
Reply: Thank you for the comment. We have added a description of the selected material to the "Experimental" section.
“As2S3 and a-Se chalcogenide glass semiconductors described in these papers has an advantage over azopolymer-based materials [33, 34] in the formation of lattice structures. The initial material formed by spraying has high indicators of uniformity of structure, uniformity of thickness. At the same time, the technology of applying multilayer coatings can be carried out by standard industrial technologies for automated application of optical coatings. The use of two types of layers As2S3 and a-Se allows optically forming a microrelief without the use of etching. And the use of a large number of thin alternating As2S3 and a-Se nanolayers makes it possible to increase the degree of heaving of the material with a small response in each pair of layers. This technology is described and studied in detail in earlier works [38]. The optimal parameters of the thickness of the layers were also selected. As in [38], we used a sample of 110 pairs of nanolayers with 9 nm As2S3 and 3 nm a-Se with a total thickness of 1.3 microns.”
- The author should add some formulas calculate the components of the electric field upon interference of a Gaussian beam and a first-order vortex beam.
Reply: We have added a method for calculating field components. We consider it inappropriate to present a detailed description of the calculations in a manuscript of the "Communication" type.
“A first-order vortex beam with a diameter σ in Cartesian coordinates (x, y) is described by the expression:
In our simulation, we consider a situation when Gaussian and vortex beams are shifted relative to each other along the x axis in the input plane . The distributions of the total intensity in the focal plane and the distributions of the intensity of individual electric field components of the studied laser beams were calculated using the Richards–Wolf expressions [41, 42]. The calculation results are shown in Fig. 4.”
- The format of some references is not uniform.
Reply: Thank you for the comment. We have fixed the references format.
Reviewer 4 Report
This is a good manuscript discussing the novel way of building the surface relief structure by holographic writing method and forming the forked diffraction grating which has application in optical communication. In this manuscript, the author had detailed study of the spatial electric field distribution and predicted the best configuration of the two beam exposure. Then the author built the device and had some characterization of it. The result is pretty clear. However, there are few questions before I suggest publishing this manuscript.
1. Could the author provide clarification of the diffraction efficiency issue? As I see before, the polarization holographic grating has potential of reaching close to 100% efficiency.
2. In the figure 1, it would be great if the author can mark the coordinate into all graphs to make it clear.
3. In the configuration d of figure 1, with one left and one right hand light interference, the result would be a rotated linear polarization in the record plane if we ignore the vertical component. So, there would be a 180-phase shift between X and Y electric field, if X and Y are in the recording plane. Could the author give some clarification?
4. There are some polarization holography papers related to this work the author could reference, such as:
https://opg.optica.org/ao/abstract.cfm?uri=ao-60-3-580
and
https://opg.optica.org/ao/abstract.cfm?uri=ao-61-11-3134
Author Response
We are grateful to the reviewers for their valuable efforts. We have significantly rewritten the paper in response to their comments. English language has been revised throughout the whole paper. We added two versions of the paper the MS Word document, and the pdf with changes highlighted in yellow.
The answer is attached as a pdf file.
Author Response File: 
Author Response.pdf
Round 2
Reviewer 1 Report
The authors have addressed the reviewer comments and the manuscript can be accepted for publication.
