Modeling a Fully Polarized Optical Fiber Suitable for Photonic Integrated Circuits or Sensors

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

1. Why choose  17λ and 13λ as the two rings' central radius? Is there any difference if the two rings' radius changed? The simulation comparison results are more convincing.

2. The simulation results show that only z-polarized light can propagate in this system. Please provide a reasonable explanation on this result.

3. This article theoretically introduces an optical fiber that only transmits fully linearly polarized light and maintains the polarization state. Do you think this can be experimentally implemented? if not, what are the limiting factors for implementation?

Comments on the Quality of English Language

Minor editing of English language required.

Author Response

Great thanks to the reviewer for the very helpful comments. I have made necessary revisions to the manuscript rigorously following these comments.

Comments:

1. Why choose 17λ and 13λ as the two rings' central radius? Is there any difference if the two rings' radius changed? The simulation comparison results are more convincing.

We add “The radii of the two rings are arbitrarily chosen as exemplary cases. The radii of the rings affect the coupling length of the fibers, thus exchanging the position of the two rings can change the resonance effect.” at line 72-74. Since this is a well-known physics of the fiber optics, we prefer not to show the comparison.

2. The simulation results show that only z-polarized light can propagate in this system. Please provide a reasonable explanation on this result.

We add “This is because in y direction the fiber has only a half-wavelength thickness, reaching the limit of diffraction, electric field oscillating in y direction and reflected by the fiber edge has mostly destructive phase difference inside the fiber, thus light cannot propagate.” At line 89-92.

3. This article theoretically introduces an optical fiber that only transmits fully linearly polarized light and maintains the polarization state. Do you think this can be experimentally implemented? if not, what are the limiting factors for implementation?

We add “Note here that this is only a modeling study. But experiments can be done by depositing a silicon film on a copper substrate [14] and photoetching it following the shape and size of this design.” At the end of the Conclusions.

Minor editing of English language required.

This is done.

Reviewer 2 Report

Comments and Suggestions for Authors

1.The incident beam is currently assumed to be an ideal plane wave . If the incident beam  is not uniform in intensity,such as the Gauss Beam, how about the results?

2. The shape and size of the prism should be described in more detail. The beam is coupled to the fiber through the prism. What factors affect the coupling efficiency?

3. The fiber needs to be placed on a solid substrate, so the four sides of a rectangular fiber can not all be free space, what is the effect of the substrate material on the fiber transmission?

Author Response

Great thanks to the reviewer for the very helpful comments. I have made necessary revisions to the manuscript rigorously following these comments.

Comments:

1. The incident beam is currently assumed to be an ideal plane wave . If the incident beam  is not uniform in intensity,such as the Gauss Beam, how about the results?

We add “Note here that in these modeling studies, we assume a plane incidence wave for simplicity，since the fiber is very thin, this shouldn’t cause significant difference from that of using a Gaussian beam.” At line 113-115.

 

2. The shape and size of the prism should be described in more detail. The beam is coupled to the fiber through the prism. What factors affect the coupling efficiency?

We add and have “The prism receiving head has the same optical properties with that of the fiber. It has the same width of the fiber. The length (l) and the half aperture angle (θ) of the receiving prism of the fiber determines the coupling efficiency, i.e. the wave amount received by the system. However, the light intensity in the fiber is also affected by the refractive index of the fiber, the aperture angle, and the polarization status of the incidence, due to the backscatter from the oblique surface of the prism, and the polarization characteristic of the fiber.” at Line 45-50.

3. The fiber needs to be placed on a solid substrate, so the four sides of a rectangular fiber can not all be free space, what is the effect of the substrate material on the fiber transmission?

We add “Note here that this is only a modeling study. But experiments can be done by depositing a silicon film on a copper substrate [14] and photoetching it following the shape and size of this design.” At the end of the Conclusions. Copper substrate as a good reflector should NOT affect the fiber transmission.

Reviewer 3 Report

Comments and Suggestions for Authors

In this manuscript, the author presented the FDTD modeling of an integrated photonic optical structure that is capable of maintaining a certain polarization state. Below I have some comments and questions which I hope the author would be able to address:

1. The author referred such optical structures as "optical fibers", but rather, it seems to me that such a structure is more of an integrated photonic coupler combined with waveguides and ring resonators. Why does the title describe this as an optical fiber? The connection is missing in terms of adapting this structure to designing an optical fiber.

PMFs, optical fibers, are typically not the same scale in size as integrated photonic circuits.

2. What is the cladding material as stimulated in this FDTD simulation? 

3. The author compared this structure to PMFs, could the author describe the polarization maintaining capability for such optical structures under different bending conditions?

Author Response

Great thanks to the reviewer for the very helpful comments. I have made necessary revisions to the manuscript rigorously following these comments.

Comments:

 

In this manuscript, the author presented the FDTD modeling of an integrated photonic optical structure that is capable of maintaining a certain polarization state. Below I have some comments and questions which I hope the author would be able to address:

1. The author referred such optical structures as "optical fibers", but rather, it seems to me that such a structure is more of an integrated photonic coupler combined with waveguides and ring resonators. Why does the title describe this as an optical fiber? The connection is missing in terms of adapting this structure to designing an optical fiber.

PMFs, optical fibers, are typically not the same scale in size as integrated photonic circuits.

Thanks to this good comment. We are trying to design a fiber for integrated photonic circuits. This truly is different from optical fiber of common sense and could be misunderstood. But I cannot find a more proper term to describe it in short, thus I prefer using the current one, begging the pardon of the reviewer and editors.

2. What is the cladding material as stimulated in this FDTD simulation? 

The cladding material in the simulation is free space. We add “Note here that this is only a modeling study. But experiments can be done by depositing a silicon film on a copper substrate [14] and photoetching it following the shape and size of this design.” At the end of the Conclusions.

 

1. The author compared this structure to PMFs, could the author describe the polarization maintaining capability for such optical structures under different bending conditions?

This is a very good question I cannot exactly answer, since no data to support my thoughts. But I think under different bending conditions, our design should work well due to the diffraction limit thickness in one dimension.

 

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

the author has solved my concern questions

Comments on the Quality of English Language

fine

Reviewer 3 Report

Comments and Suggestions for Authors

The author addressed my questions. The manuscript is ok to publish in my opinion. For the last question I brought up in my previous review, the bending conditions can be simulated as well for more rigorous analysis, but I do agree that the diffraction-limited design in one dimension would help.

1. The author compared this structure to PMFs, could the author describe the polarization maintaining capability for such optical structures under different bending conditions?

This is a very good question I cannot exactly answer, since no data to support my thoughts. But I think under different bending conditions, our design should work well due to the diffraction limit thickness in one dimension.