Q-Switched High-Order Harmonic Mode-Locked Noise-like Pulses in an Erbium/Ytterbium Fiber Laser

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript presents a systematic experimental investigation of Q-switched high-order harmonic mode-locked (QHML) noise-like pulses generated from an Erbium/Ytterbium (Er/Yb) co-doped double-clad fiber (DCF) laser. Before acceptance, I have following comments.

1. What specific advantages does Er/Yb co-doping provide over using only erbium-doped fiber for achieving Q-switched harmonic mode-locking? Why was a ytterbium-only or erbium doped fiber not considered, particularly in relation to emission wavelength and pulse dynamics?
2. What is the physical origin of the dual-wavelength emission observed in Fig. 3a.
3. The reported pulse duration and repetition rate show no significant change between the QML and QHML regimes. On what experimental basis is the transition from Q-switched mode-locking (QML) to Q-switched harmonic mode-locking (QHML) identified?
4. What are the practical applications of the observed dual-wavelength emission in your laser system?

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The paper "Q-switched High-order Harmonic Mode-locked Noise-like Pulses in an Erbium/ytterbium Fiber Laser" is devoted to the study of an erbium/ytterbium double-clad ring fiber laser based on nonlinear polarization rotation operating in a self-starting Q-switched high-order harmonic mode locking noise-like pulse regime. The manuscript clear, relevant to the field, and presented in a well-structured manner. I recommend this manuscript for publication if the following edits and clarifications are made:

1. Please explain in detail the nature of the occurrence of the spectral peak at a wavelength of 1605.9 nm.
2. What is the power loss of a 3-port optical fiber bench in a laser circuit?
3. Line 174 talks about the proper pump power level. What is this power level (W)?
4. What was the pump power level used to obtain the results shown in Figure 4?
5. The captions in figures 4 and 5 need to be made larger.

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

As is known, the physical mechanism of ML fiber laser is very complicated and diverse phenomena have been experimentally observed. Further theoretical and experimental studies are desired for this subject.

This paper has made an experimental study on passive ML of Er/Yb fiber laser in particular. The experimental scheme employed is rather popular but provides some new information which enriches the physical information about ML fiber lasers, including achieving about more than ten-times higher order harmonic locking against previously known in QHML-NLP. The presented experimental results and associated discussions will help fiber laser people to  deepen their understanding of still unclear properties of ML fiber lasers.

Author Response

We thank the reviewer for taking the time to evaluate our manuscript. We sincerely appreciate their contribution to the review process.