Amplified Nonreciprocal Reflection in a Uniform Atomic Medium with the Help of Spontaneous Emissions

Round 1

Reviewer 1 Report

The manuscript from Hong Yang et al. presented a theoretical study of optical nonreciprocial  effect for reflected optical beam in atoms. Specifically, the authors found that the supposed scheme can be extended to realize the perfect nonreciprocial reflection of amplified probe beam via using multi-level atomic system driven by multi-fields with spatial distribution intensities. The topic itself is interesting and the novelty was clearly presented to the readers.  

The append physical discussions may be necessary for publication in the journal.   

The key point of this manuscript was the nonreciprocity for probe beam, which was amplified and reflected in atoms. The important mechanisms of amplification and reflection may need to be explained in detail, e.g. after eq.2, why the authors use the S thin layers to further deal with the eq.2, the necessary discussion might be helpful to show the reflection.

Furthermore, e.g. Fig.2 showed the reflection rate of probe beam, which is normalized by input probe? The R>1 means amplification? Why it is amplified?    

The physics related to nonreciprocity is also needed to be discussed, indeed, the decay rate of atoms plays the key role, it is suggested to investigate the physical mechanism of the symmetry breaking.

the manuscript is well written

Author Response

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Reviewer 2 Report

My comments are summarized in the PDF file.

Comments for author File: Comments.pdf

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Reviewer 3 Report

The authors propose a four-level N-type atomic system driven by two strong coupling fields and one probe field. This system utilizes spontaneous emission and the linear variation of the coupling field to achieve amplified nonreciprocal reflections with atoms homogeneously distributed. Although the results presented in the paper seem interesting, I cannot recommend it for publication for the following reasons:

1. The citation of references in the paper is disorderly and disorganized.

2. The manuscript is very obscure to read, i.e., the authors do not specify the basis vector of Eq. 1 in the paper.  Additionally, the authors do not indicate the theoretical foundation for the dynamic process of density matrix elements under equation 1 (lines 77-86).

3. The authors do not point out the advantages of this proposed scheme compared to others in the manuscript.

The manuscript is well written.

Author Response

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Round 2

Reviewer 3 Report

Although the author has already responded to previous comments, the manuscript seems more suitable for publication in Photonics. However, the references in the paper are still disorderly; for example, in the introduction, the Refs.[12-19] appear after Refs.[29, 31], and so on. Also, some references are not cited in the paper, such as Ref.[13, 14, 30, 51]?

English language fine. 

Author Response

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