Towards Deep Integration of Electronics and Photonics
Round 1
Reviewer 1 Report
Review „Towards deep integration of electronics and photonics“
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In the manuscript the authors give an overview over the work of the last decade in plasmonics research with the aim to combine electronics and photonics below the dimensions given by the diffraction limit of light. After a short walkthrough through plasmonics and different plasmonic materials, concepts of electro-optical modulators are introduced, followed by polarization modulators and single photon light sources. In the end the quantum nature of plasmons and scaling effects are introduced as well as a short view on the possible applications of other polaritonic excitations.
The topic of the review is of great interest and a review in this topic is a good idea for researchers entering this ever growing field of more and more applied research. However, the present manuscript fulfils the task of an review not completely satisfactory.
First of all, the scope is quite large. Each subtopic could be the center of an own review. With this in mind many imho important references are missing and therefor the aim to introduce to the actual state of the field is slightly missed. I will deliver some examples below.
Second the language is often not as precise as necessary for an introductory text. Some paragraph tell the same story twice, others stay vague in the property description. Also some examples below.
To close this introduction I cannot recommend the review for publication in its present form, but is has potential.
One further remark: To save time for both reviewer and authors, please deliver a manuscript version with line numbers. I won't review the revised version without - sorry.
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Topical comments:
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abstract:
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5th line: most fundamental level -> not well defined as one could understand also "at the quark or string level".
same line: "hybrid quasi ... matter" -> why not introduce the well known word "polariton" here?
line 10: can be developed further ... -> this contradicts the notion in line 5. further developed than most fundamental sounds awkward ;)
Introduction:
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The first two sentences have no greater content. "Things" sounds too sloppy.
line 4-5: maybe delete the sentence.
line 9-10: maybe remove this sentence
line 11-14: This is a sentence for the conclusion, with a possible outlook.
Second paragraph:
line 6-7: Strong coupling ist NOT mandatory for strong interaction. Every waveguide mode is by definition not strongly coupled and can be efficiently modulated
line 8: explain the electro-optical effect or at least refer to an explanation.
line 9: at the level of single chips -> to imprecise. Of course chips can be designed that combine both world, however, the scale of parts varies greatly within this chip.
line 10-12: Mixed -> Coupled. In general, here should be already a list of all the mixed states. And to be true, only the plasmon is the described mixed state. All the other quasi-particles are also couple with the atom (exiton / (optical) phonon) or other properties than charge (magnon).
Page two after Fig 1.:
General remark: The explanation of the fundamental physics of SPPs does not belong into an introduction, but, into maybe section 2.
First paragraph:
line 8-9: The first studies of plasmons were performed by Faraday with colloidal solutions of gold: https://doi.org/10.1098%2Frstl.1857.0011
line 10-11: Applications of LSP also contain SNOM/TERS. Please mention and refer. Structural coloring is mentioned, but not identified as application. Could be added for completeness.
line 14: the word "quasiparticle* is used imprecisely here.
Section 2
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paragraph 1: please add also comments on the advantages of gold and silver with references. This is also true for fabrication methods, when you mention them. However, in a purely materials section, this would not be necessary.
paragraph 2: contains no new insights and could be left away.
paragraph 3: The paragraph needs to be reworked. Most of the claims are not well referenced or explained. Phrases like "which might be challenging" are not scientifically.
paragraph 4: Here again, a phrase as "are said to be" is not helpful in a review.
Also at the end of the paragraph the relative change in refractive index would be nice to know. Here "order of one" does not help too much.
paragraph 6: please mention the free space wavelength range of graphene plasmons.
paragraph 7: this paragraph could be shortened.
Section 3
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paragraph 1:
enumerate the classes of devices
line 7-8: delete sentence
line 9-10: "may" -> "can"; also add references.
paragraph 5: should be written more concise.
paragraph 7: line 16: start new paragraph here.
The class of mechanical modulators is completely missing!
Section 4
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paragraph 2:
lines 3-6 redundant sentence -> delete
paragraph 6 line 3: individual atomic structure sounds strange. Reformulate it to note that the solid state approaches break down or similar.
reference the work of e.g. Baumberg for the influence of single atoms to resonances.
paragraph 7: Lithography can be very helpful, if the raw material is mono-crystalline. Please mention gold flakes here.
last paragraph: compare with the concept of photon blockade.
Section 5
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the description of polaritons is quite imprecise here, too. It is imho important to focus on the coupling aspect. "Mixing" and "interaction" are not enough to describe this.
Section 6
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I would like to read a comment on the achievable computation speed. It s much slower for electro-optical components than for purely photonic components.
Referencing comments:
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Introduction:
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There is NO reference in the first two paragraphs. To learn to know the state of the art in electronics and photonics some reviews should be cited.
Page two after Fig 1.:
First paragraph:
line 2: refs [1,2] do not tackle volume plasmons in any detail. Should be put together with ref [3]
Section 2
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line 2: ref for the ancient usages missing.
end of paragraph 1: Ref [22] is not needed within the scope of this paper and section.
paragraph 2: if rewritten, should contain refs to the claims of semiconductors and property control by external electrical field*s*.
paragraph 4: Why are refs [26,27] chosen? They are not fundamental or reviews themselves.
paragraph 7: add refs for the HfO_2 results
Section 3
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paragraph 2: add references to elucidate the LDOS topic.
paragraph 3: Bozhevolnyi has some reviews about plasmonic waveguide to be cited here.
refs 56 an 55 are in the wrong order.
the very end: Reference to the claim needed.
Section 4
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is in general poorly referenced, e.g. I miss the works of J. Dionne.
Grammar/Typo comments:
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3rd line abstract: way -> path
8th line abstract: utility -> use, benefit, advantage, value
9th line abstract: paradigm*s*
Introduction:
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1st paragraph: The wording is inconsistent. E.g. it is not clear what macroscopic and microscopic really means.
line 21: the deep -> a deep
Page two after Fig 1.:
First paragraph:
line 1: *A* plasmon is def...
line 3: ... of *free* charge carriers ...
line 4: light -> photons
line 8: ... films were studied since over a century ...
line 13: light-matter coupling *at resonance* and ...
line 14: *field* confinement [...]
Second paragraph:
line 2: for TeX please type "e.g.\~the" to get the spacing right
page 3:
line 1: ... in Sec. 4 ... -> delete "the"
Section 2
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paragraph 4:
line 9: in *the* NIR-Range
line 11: electric field *can* be used to *realize* ITO
paragraph 5:
line 6: .. depends significantly on *the* free charge density *which enters* the plasma ... (maybe add formula - it's a review)
Section 3
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paragraph 2:
last full line: remove *a*
Section 4
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paragraph 2:
line 7: *A* more det...
paragraph 3:
line 3: remove *the*
paragraph 4:
beginning: SPR*s* ...
end: as one of the conclusions it is suggested that plasmonic components could be used ...
paragraph 7: end: one should *realize* transfer loss ...
Author Response
Please see the attachment. Thanks.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Point 1:
The article has a couple of readability problems. First, insufficient and inconsistent rest comma makes reading hard. In second paragraph in Introduction section, first and fourth sentence have almost same sentence structure but fourth sentence only has rest comma in the sentence, which makes minor difficulty in reading. Second, in the last paragraph of section 3, fifth sentence has a typo, 'A plasmonc' should be 'A plasmonic'.
nic'.
Point 2:
There is a lack of explanations about the specific examples. For example, you mentioned ”Nevertheless, this epsilon-zero point is quite special, since properties of materials vary significantly there.” in the fifth paragraph of section 2. Then you progress this journal putting emphasis on ENZ effect for a while. But there is no details about the 'properties of materials vary significantly there.' It would be better to add specific details, like which properties are varying.
Like above, in the next page, you mentioned about the improvements in the area of light emission. However, there is no examples or specific values of the differences. It would be better to put any experiment results or numerical values as reference.
Point 3:
The article seems to need more figures overall. For example, when you explain plasmonic waveguiding, there would be difficulties in understanding because of a lack of figures. Also, if you add some figures about principles of electro-optical modulator, the readers of this article may understand the electro-optical modulator models (Figure2) more easily.
Author Response
Please see the attachment. Thanks.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Dear authors,
After the first round of review I have only minor proposals to improve the manuscript.
On page 2 lines 36-38 should be moven to the end of the paragraph. As well, the methods of Cathodoluminescence an SNOM itself should be added as methods to image plamons.
Best regards
Author Response
Dear Reviewer,
We appreciate your valuable suggestions. All your comments result in a great improvement of the text.
Regarding the second revision, the cathodoluminescence method is added and the 36-42 line paragraph is slightly rearranged correspondingly.
Sincerely,
DrDrachev
