Second-Harmonic Generation in Aggregates of Lithium Niobate Particles Formed upon Suspension Freezing
Round 1
Reviewer 1 Report
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Author Response
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Reviewer 2 Report
Comments
This paper by Matrokhin et al. presents the second harmonic generation (SHG) shown from the frozen LiNbO3 nanocrystal solution. Aggregated nanoparticles in a frozen solution formed a thin film, and the thin film induced second harmonic generation. The conversion efficiency was smaller than that of nanocrystals deposited on glass or the material in a powder state. Freezing the nanoparticle solution to form a freestanding thin film is interesting.
Suggestion for authors
Hopefully, answering those questions would be helpful to improve this work.
1. Are you freezing from the bottom side of the solution to generate the thin film at the top side? Do you have a microscopic image of the thin film?
2. How uniform is the thin film generated from the aggregated nanoparticles? Can you generate the same SHG from the whole surface of the thin film?
3. Can you control the thickness of the generated thin film?
4. In Figure 4b, the meaning of the "thickness of the suspension" is ambiguous. Does this mean the thickness of the thin film or the solution?
5. Figure 4b is measurement data, but the measurement points shown in Figure 3 or Figure 4a are missing.
6. How did you calculate the efficiency of conversion? Does it depend on the power of the laser?
Author Response
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Reviewer 3 Report
Review of the article “Second harmonic generation in aggregates of lithium niobate particles formed upon suspension freezing” Authors: Sofia Umanskaya *, Anton Matrokhin, Mikhail Shevchenko, Maria Tareeva, Anna Kudryavceva, Nikolay Tcherniega
In this work, the authors used the method of second harmonic generation (SHG) to study the process of solidification of harmonic nanoparticles (HNP) LiNbO3. Non-centrosymmetric metal oxide HNPs with high second-order susceptibility are widely used for applications in bioimaging, holography, multiphoton spectroscopy, etc. Among GNPs, LiNbO3 nanocrystals generate SHG very efficiently. Therefore, the choice of the object of study was made correctly.
The work presented in this manuscript is interesting and attracts attention. The methods used are benchmark and the results have been properly characterised and analysed. The conclusions made are supported by the results. The novelty of the work is clear. It would be interesting to measure the photon mean free path or the density of particles after freezing, although it is obvious that this is difficult to implement experimentally.
I have some comments on the manuscript, text from article in italics:
Line 70 “A portable spectrometer Ocean with spectral resolution was used…”
It is necessary to indicate the brand of the spectrometer and the value of the spectral resolution.
Line 72 “At a certain concentration of LN particles in the suspension…”
It is necessary to specify the exact value of concentration.
Figure 4a caption: Angle (rad)
Apparently it is necessary to write: Angle (deg).
In the last sentence in the conclusions (line 154), it is written that: “SHG signal enhancement is affected by…, and by the processes of photon entanglement with a significant decrease in the mean free path value.”
However, nothing was said in the text about this influence, and in general the process of photon entanglement was not mentioned. If this is a known fact, then it should be displayed in the text and an appropriate reference given. Otherwise, this phrase should be deleted.
In general, the article is very good and can be published in the journal "Photonics".
Hope that my comments will be taken into account.
Dr. Boris Umanskii,
Leading Scientific Researcher,
Laboratory of Liquid Crystals,
FSRC “Crystallography and Photonics”
Author Response
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Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
Dear Authors,
I appreciate your response and the corrections concerning points 4 - 7.
About points 2 - 3, I was curious how constant the thickness of the thin film is. How does the film look on the liquid? If a microscopic image is unable to get, could you take a photograph of the thin film? Do you see any pattern on the thin film? Does the intensity of the SHG the same in the entire area?
I understand that uniformity of the thin film is not a critical issue for this work. But I believe providing that information can be helpful for researchers who try to generate a thin film using this method.
