A High-Quality Optical Sensor with High Resolution Based on Coin-like Resonator
Round 1
Reviewer 1 Report
The paper presents the plasmonic sensor based on a MIM waveguide for temperature sensing applications. The paper is written in an adverse English language which makes it difficult to understand. Moreover, the paper does not contain any novelty of the idea. It is the same research that has been published several times and I don't have any enhancement in the idea. The cavity is a ring resonator which the author has named a "coin", for no reason. Most importantly, the same design or even enhanced designs are published earlier such as: https://www.sciencedirect.com/science/article/abs/pii/S0030401822003005; https://www.frontiersin.org/articles/10.3389/fphy.2022.1026494/full.
The introduction section is weak with no detailed information on the previous works on temperature sensors, whereas the author has talked about refractive index sensing which does not make any sense.
Also, there is no detailed parameter optimization study has been presented. Based on my experience in this topic, I am not willing to accept this paper.
Poor English.
Author Response
We are grateful to the reviewers and editors-in-chief for their comments, which have helped us a lot. It is a great honor to have your guidance. According to your guidance, we have made detailed modifications and sorting, and now the PDF document is in the attachment, please check! Thank you so much.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
In this work, the author proposed a metal-insulator-metal (MIM) structure as a nanoscale plasmonic temperature sensor by combining the waveguide structure with a coin-like resonator. By modifying the parameter of the structure, the maximum temperature sensitivity reaches 0.38 nm/℃ and the figure of merit can be as high as 30158. This is an interesting work. I would like to recommend its acceptance in Photonics after a minor revision.
The detailed comments are in the following that need the author to further address.
1. When the authors describe the schematic of the proposed structure, the two stubs are not introduced. Please give more details of them, references at least.
2. For all the figures showing magnetic field distribution, for example figure 3(d) (f) and (h), please unify the scale bar with the same scale.
3. Please give references for the FOM you use for the calculation.
4. The references 29 and 30 are the same, please correct them.
Author Response
We are grateful to the reviewers and editors-in-chief for their comments, which have helped us a lot. It is a great honor to have your guidance. According to your guidance, we have made detailed modifications and sorting, and now the PDF document is in the attachment, please check.Thank you so much!
Author Response File: Author Response.pdf
Reviewer 3 Report
The Authors propose a MIM-based coin-like resonator acts as biosensor. The reported results have been numerically achieved by using FEM-based solver. Although the results seem promising, an improvement of the manuscript is needed to be suitable for the publication.
Here, my comments to the manuscript:
1. In the Introduction, the Authors should discuss about the benefits of the MIM structure, comparing the performance with dielectric solution or hybrid ones (see, e.g., Advancing the sensitivity of integrated epoxy-based Bragg grating refractometry by high-index nanolayers. Optics Letters, 45(19), 5510-5513, 2020; Highly sensitive refractive index sensor based on polymer bragg grating: A case study on extracellular vesicles detection. Biosensors, 12(6), 415, 2022.).
3. Figure 1 should report also the device cross-section, pointing out the main features and materials.
4. The operation of the stub should be clarified, and also its relevance in the design.
5. The spectra of all rings show a Fano behaviour, desirable for sensing application. However, this shape clashes with the standard Lorentzian shape of resonator. Please clarify.
6. In terms of sensitivity, the Q-factor plays a crucial role. For this reason, please comment on it and compare with the other configurations also based on dielectric materials (see, e.g., Comprehensive mathematical modelling of ultra-high Q grating-assisted ring resonators. Journal of optics, 22(3), 035802, 2020; Ultralow 0.034 dB/m loss wafer-scale integrated photonics realizing 720 million Q and 380 μW threshold Brillouin lasing. Optics letters, 47(7), 1855-1858.).
7. All spectra should be improved in terms of wavelength resolution and colorbar (Fig. 3(d-i)).
8. The configuration sketched in Fig. 4(a) results very interesting with promising results. For this reason, the Authors should more stress the improvements of the proposed structure with respect to the one reported in Fig. 1(a), mainly in terms of ER and Q-factor.
2. The English should be improved in the whole manuscript.
Author Response
We are grateful to the reviewers and editors-in-chief for their comments, which have helped us a lot. It is a great honor to have your guidance. According to your guidance, we have made detailed modifications and sorting, and now the PDF document is in the attachment, please check! Thank you so much.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
I have serious concerns related to the paper which are not properly addressed. Paper is still not acceptable in its current form.
1) What is the formula of Sensitivity which has been used?
2) What is the formula of FOM, in the case of Fano resonance, The formula S/FWHM can not be applied. Readers would like to know how you obtained such a high FOM. Consult https://linkinghub.elsevier.com/retrieve/pii/S1386947719311336.
3) Figure 1a and 4a are confusing. If two designs are studied, then they should both be shown at the beginning of the paper. Because the author has highlighted the ring resonator design but they are talking about coin resonators.
4) In Table 3, the wavelength range should be mentioned for all the studies. Also the temperature ranges. And mention which one of them is Fano-based sensors or Lorentzian line-based sensors.
5) English has to be improved. Its unsatisfactory.
6) The author said "The quality can be fur- 173 therly enhanced when combined with other structures such as photonic crystals to reach 174 as high as 109". My question is how? The author has not shown Q-factor then how they comment on it. The author has only shown FOM. I suggest calculating the Q-factor and LOD of the device.
Need extensive English correction.
Author Response
We are grateful to the reviewers and editors-in-chief for their comments, which have helped us a lot. It is a great honor to have your guidance. According to your guidance, we have made detailed modifications and sorting, and now the PDF document is in the attachment, please check! Thank you so much.
Author Response File: Author Response.pdf
Reviewer 3 Report
The Authors have modified the manuscript according to the Reviewer suggestions. However, several flaws are still present in the manuscript (i.e.,COLSOL). Please read carefully it.
A careful reading of the English language is needed.
Author Response
We are grateful to the reviewers and editors-in-chief for their comments, which have helped us a lot. It is a great honor to have your guidance. According to your guidance, we have made detailed modifications and sorting, and now the PDF document is in the attachment, please check! Thank you so much.
Author Response File: Author Response.pdf
