Polarization-Insensitive, Orthogonal Linearly Polarized and Orthogonal Circularly Polarized Synthetic Aperture Metalenses
Round 1
Reviewer 1 Report
The manuscript entitled on “Polarization-insensitive, orthogonal linearly polarized and orthogonal circularly polarized synthetic aperture metalenses” numerically demonstrates three types of synthetic aperture metalenses (SAMs) for high resolution imaging. Compared with the conventional whole aperture metalenses, SAMs can achieve the equal optical resolution by combinations of small apertures, in which the effective area of the SAM is smaller than that of the conventional whole aperture metalens, resulting in a low fabrication time and cost. While the principle and methodology of the SAM metalens with polarization features is not new, the results shown in the manuscript could be of interests in the optical engineering community. It could be marginally published after major revision.
1. To clearly show the relationship between the full aperture metalens and the SAMs formed by sub-aperture, authors should show the relationship of the phase pattern of the full aperture metalens and SAMs, such as in Figure 7.
2. Obviously, MTF of the SAMs in the mid-frequency range is lower than that of full aperture counterpart, the author should show how the low MTF in the mid-frequency range of the SAMs is recovered in the imaging.
3. In the polarization imaging, such as those shown in Figures 4, 6, and 9, what is the extinction ratio between the two orthogonally polarized channels?
4. Mistakes can be found in the manuscript frequently. The manuscript should be thoroughly read to iron out typos, symbol and grammatical errors.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
In this manuscript, authors design and simulate polarization-insensitive, orthogonal linearly polarized and orthogonal circularly polarized synthetic aperture metalenses. Using synthetic aperture to improve the cutoff frequency of the metalens and achieve equivalent large aperture metalens. The subject of the paper is interesting. However, here are some problems need to be addressed.
1. The English writing should be improved, there are some errors.
2. More details about simulation should be given, for example, what kind of boundary conditions, what kind of wave source. Which EM simulation soft is used? CST or HFSS?
3. What is the permittivity of the silicon in simulations?
4. As shown in Figs.2,4,6, and 7 for the electric field distribution, it is not clear, is the z-component (Ez) or absolute value (|E|) of E-field distributions ?
5. What is the advantage of the proposed circularly polarized synthetic aperture metalenses compared with the previous designs
6. The authors should reference other metasurface metalenses published earlier:
[A] A broadband achromatic metalens for focusing and imaging in the visible, Nat. Nanotechnol. 13 (3) (2018) 220-226.
[B] Subwavelength focusing by engineered power-flow conformal metamirrors, Phys. Rev. B 104, 235409 (2021).
[C] Efficiency adjustable terahertz circular polarization anomalous refraction and planar focusing based on a bi-layered complementary Z-shaped graphene metasurface, J. Opt. Soc. Am. B 39(3), 705-712 (2022)
[D]Spin-selected focusing and imaging based on metasurface lens,Optics Express Vol. 23, Issue 20, pp. 26434-26441 (2015)
[E] Efficiency tunable broadband terahertz graphene metasurface for circular polarization anomalous reflection and plane focusing effect, Diamond & Related Materials 131 (2023) 109605
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
The authors present interesting singlet metalens arranged as a synthetic aperture with multiple sub-apertures. I have two suggestsions.
1) The MTF should be calculated with higher frequency resolution. The current plots have some sharp points that seem like discontinuous.
2) How MTF change when wavelength changes? The synthetic aperture method seems to be very useful for improving the limit of large aperture chromatic aberration problems.
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Reviewer 4 Report
The authors design a lens with polarization-insensitive and study theeffect of the synthetic aperture.
The paper is suitable for publication after the following ssue:
1) In the figure 1, they show the unit cell. What are the limit of the structure and the minimum height to obtain a difference of the phase [0°, 360°]
2) What are the effect of the loss.
Author Response
Please see the attachment
Author Response File: Author Response.docx
Round 2
Reviewer 2 Report
I think that the current version can be accepted.
Reviewer 3 Report
No further comments for additional revisions.
