Multiplexing Perfect Optical Vortex for Holographic Data Storage

Round 1

Reviewer 1 Report

This paper proposes a multiplexing method for holographic data storage using a perfect optical vortex. The authors claim that using a perfect optical vortex, where the spot size does not depend on the topological charge, can shorten the signal data distance, increasing recording density and reducing errors. Since the idea of multiple recordings using an optical vortex itself has already been reported in the literature [12], the novelty of this paper lies in the use of this perfect optical vortex. However, although there is an experimental verification of the principle of signal reconstruction, the authors cannot demonstrate with evidence the 50% increase in recording density. It is also of concern that the paper contains many typographical errors. Therefore, the reviewer thinks this paper is not worth publishing in "Photonics" in the present form. The following suggestions may help revise this paper.

(1) Typographical errors

- P.1, line 28, challengde -> challenge

- P.3. Eq(3) 1>=p>=P, 1>=q>=Q -> 1<=p<=P, 1<=q<=Q

- P.3 line 82, lambda is not shown in Eq(6), it should be r.

- P.3. line 86, line 89, simpling -> sampling

- P.4 Fig.2 caption, orbital vortex -> optical vortex

(2) The right side of Fig. 4 shows a "POV-multiplexing hologram." Is it really a multiplexing hologram?

(3) On page 6, line 152, why are the thresholds not equally spaced? What is this artificial value determined from? Is it a universal value? Or is it a value that must be changed for each experiment?

(4) On page 8, line 200, the authors state that the recording density increases by 50%. However, Fig. 7 does not appear to show an increase of 50%. It should be explained more carefully because it is directly related to the conclusion of this paper.

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

In this work, the authors propose to use a perfect optical vortex for holographic recording. The authors experimentally showed that when restoring an image, the BER error for the number of recording pages 10 (Fig. 7) is approximately 1.5%, which is less than the error when recording with conventional OVs (BER is approximately 2%). But reducing the error by 0.5% is not significant. The very idea that the diameter of a perfect vortex does not depend on the topological charge deserves attention, and therefore the use of POV instead of OV is more rational. But the work itself has many shortcomings. The work can be published after the authors take into account the comments.

Comments

1) Equation (4) is not a Gerchberg-Saxton algorithm, but a discrete Fourier transform.

2) Line 82 says that λ is the wavelength in (6), but there is no λ in (6).

3) Line 88 says that f in equation (7) is frequency. This is wrong, f is the focal length of a spherical lens.

4) Equation (8) is not correct, since the dimensionless value λ/w0 is on the right side, and the dimensional value d min is on the left side.

5) In Fig.2 there is a value d0, which is not in formulas (1)-(11). It is only written that d0 is a sampling distance.

6) Upon receipt of fig. 2 does not indicate what were the values of λ,w0, f, d POV. This information must be provided.

7) Articles should be added in which POV was first proposed (Opt Lett 38, 534 (2013)) and the optimal phase DOE for POV generation (JOSA A 33, 2376 (2016)).

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

Multiplexing perfect optical vortex for holographic data storage

In this manuscript, the authors study holographic data storage (HDS) as a promising recent optical technique for high-capacity data storage. In their study, they propose an approach to enhancing the storage density in HDS by multiplexing a perfect optical vortex (POV) hologram. In their research, they found that for the POV-multiplexing hologram of six data pages, each one can be reconstructed successfully. In addition, we investigate the impact of axicon periods and multiplexing numbers on storage performance. In addition, their proposed multiplexing approach offers a valuable solution for achieving high-density and secure holographic data storage systems.

The present manuscript looks fine, except for a few points that must be clearly stated in the manuscript:

Ø To make the manuscript more readable and understandable, the author has to define the terms used in their manuscript, like ‘’optical vortex and many more.

Ø Also, can the author add an appendix at the end of the manuscript that contains a brief description of the mathematical method he used?

Ø In the results section, the author uses HWP to control the state of polarization of the laser beam, Can the author add a few lines describing the effect of altering the polarization state of the laser beam on the storage capacity of their hologram?

With my best

Multiplexing perfect optical vortex for holographic data storage

In this manuscript, the authors study holographic data storage (HDS) as a promising recent optical technique for high-capacity data storage. In their study, they propose an approach to enhancing the storage density in HDS by multiplexing a perfect optical vortex (POV) hologram. In their research, they found that for the POV-multiplexing hologram of six data pages, each one can be reconstructed successfully. In addition, we investigate the impact of axicon periods and multiplexing numbers on storage performance. In addition, their proposed multiplexing approach offers a valuable solution for achieving high-density and secure holographic data storage systems.

The present manuscript looks fine, except for a few points that must be clearly stated in the manuscript:

Ø To make the manuscript more readable and understandable, the author has to define the terms used in their manuscript, like ‘’optical vortex and many more.

Ø Also, can the author add an appendix at the end of the manuscript that contains a brief description of the mathematical method he used?

Ø In the results section, the author uses HWP to control the state of polarization of the laser beam, Can the author add a few lines describing the effect of altering the polarization state of the laser beam on the storage capacity of their hologram?

With my best

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The paper has been revised according to the comments.

Reviewer 2 Report

The authors took into account all my comments and the work can be published