Inverse Design of Ultra-Compact and Low-Loss Optical Phase Shifters

Round 1

Reviewer 1 Report

This work presents a novel PS with arbitrary phase shift designed using 158 a shape optimization method. It is novel, therefore, I think it can be published in present form. 

Author Response

Thank you very much for consideration of our manuscript and for recognising our work.

Reviewer 2 Report

The authors demonstrate inverse design methods to accurately control the phase of photonic waveguides. Inverse design has significantly impacted the photonics community, unlocking numerous functionalities that were previously unattainable at such a small form factor. These methods have also been utilized to fabricate robust designs, enabling functionalities that were previously out of reach. However, this paper lacks the necessary significance to showcase how inverse design can achieve functionalities previously deemed unattainable. The study also lacks in-depth demonstration of how inverse design methods achieve a smaller form factor, enhanced robustness, and more precise design control compared to conventional methods. Therefore, I cannot recommend the publication of this work in Photonics unless the paper undergoes major revision, clearly delineating how the authors' methods achieve results that were otherwise unattainable using conventional techniques.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

This is a very interesting paper that tries to achieve passive phase shifting through a novel device structure. While the study is very interesting and thought-provoking, I have certain concerns that should be addressed:

1) It is unclear what would be the application of such a device. Could you provide some practical situations where such a device might be useful?

2) Which software package was used for the simulation of this study?

3) It seems like the authors have combined the inverse design method and the PSO method. Could you provide details about how such a combination was achieved?

4) The final structure design looks difficult to be fabricated. Given the fabrication of a device is never perfect, how tolerant is the design to fabrication errors? 

5) The parameters shown in table 1 seem to suggest that it is a stepped structure, whereas the figures seem to suggest that it is a spline structure. What is the shape of the actual structure that was simulated?

 

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 3 Report

I believe the quality of the manuscript has been greatly improved by the authors. I just have two suggestions with regard to the methods.

1) Could you please include the formula you used to create the spline? 

2) In the paragraph starting at line 149, the authors talk about validating the designed phase shifters. it is unclear whether this validation was carried out using simulation only or was the structure fabricated as well. In case it was fabricated, the SEM picture should be provided to show the resulting structure after fabrication.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf