Round 1

Reviewer 1 Report

 

Brief summary

The manuscript entitled “Study on the difference of wavefront distortion on beams caused by wavelength-differences in weak turbulence region” discusses a mathematical model describing the cross-correlation of wavefront distortions between two co-propagating laser beams. The model is applied in experiment by an adaptive optical setup (Shack-Hartmann sensor + deformable mirror loop). The topic is relevant for free-space optical communication where laser beams typically suffer atmospheric turbulence. In this special case, two beams (signal and beacon with different wavelengths) experience dispersion that causes wavefront distortion.

 

The paper explains the work nicely to the reader. The main experimental finding of the work is that the signal quality is increased by optimizing the beacon beam with the cross-correlation matrix of the two beams. Also, simulations with the mathematical model compare the influence of beam waist, transmission distance, and refractive-index structure constant on the cross-correlation between angle-of-arrival fluctuations at four different combinations of signal-beacon-wavelengths.

 

This work could be suitable for publication in Photonics, answering the comments below.

 

Major comments:

1. On page 6, line 208 to 215, the author of the paper mention that the studied correlation is also related to the distance between two points in the wavefront. Please explain or discuss why there is no figure in the presented work which shows the cross-correlation coefficient over the distance between two points in the wavefront.

2. On page 12, starting with line 364, the authors conclude the paper. I would find it interesting to the reader if there would be a optimal set of the parameters in the study that should be used in practical implementations. And what would be the next steps?

Minor but still important comments that should be addressed:

1. Page 2, line 50, line 51: Please refer to the cited authors in a more appropriate way, i.e., change Toselli to Toselli et al., and David to Voelz et al.

2. Page 8, line 269 to 272: The symbol for function W(x,y) is named at the same time as distorted and measured wavefront. This may confuse the reader at equation (12) written as W(x,y)=W(x,y)-W0 (x,y). Please change them to individual symbols.

Typos

1. Please correct the section number on line 144, i.e. change 2.1. to 2.2

2. All figure captions: Please remove the trailing dot after Figure, e.g., change “Figure. 1” to “Figure 1” and so on.

3. Line 279, line 299,…: Please provide equation (21) or the correct number.

4. Line 321: Please provide citation [26] to the reader.

    

 

 

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

In this paper, the authors analysis the wavefront-distortion differences caused by signal and beacon light wavelength differences in weakly turbulent regions. I think the research results obtained have some useful value in applications of optical communication. So the manuscript can be accepted for publication in Photonics. Before final accept, I have some minor comments:

(1) Formula editing should be standardized. For example, the formula and text font should match.

(2) In Section 2 of the article, the authors analysis the angle of arrival fluctuation compensation coefficient at different wavelengths, and phase relationships between Gaussian beams of different wavelengths, please explain the relationship between angle of arrival fluctuation and wavefront phase.

(3) Please indicate whether the wavefront-distortion differences is related to polarization of Gaussian beams with different wavelengths.

(4) The author should added more references about the adaptive optics.

In this paper, the authors analysis the wavefront-distortion differences caused by signal and beacon light wavelength differences in weakly turbulent regions. I think the research results obtained have some useful value in applications of optical communication. So the manuscript can be accepted for publication in Photonics. Before final accept, I have some minor comments:

(1) Formula editing should be standardized. For example, the formula and text font should match.

(2) In Section 2 of the article, the authors analysis the angle of arrival fluctuation compensation coefficient at different wavelengths, and phase relationships between Gaussian beams of different wavelengths, please explain the relationship between angle of arrival fluctuation and wavefront phase.

(3) Please indicate whether the wavefront-distortion differences is related to polarization of Gaussian beams with different wavelengths.

(4) The author should added more references about the adaptive optics.

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript can be accepted for publication in Photonics. But, before final accept, some comments about manuscript need be corrected.

(1) the authors analysis the wavefront-distortion differences caused by signal and beacon light wavelength differences in weakly turbulent regions. How much correction of beam front aberration differences at different wavelengths can improve the overall beam quality.

(2) The aberration difference exists mainly in the high frequency aberration part or the low frequency aberration part, and how it is affect the beam quality？

(3) Whether the difference in aberrations between beams of different wavelengths mentioned in the paper can be corrected by means of multi-stage distortion mirror correction.

good

Author Response

Please see the attachment

Author Response File: Author Response.docx