Study of Fe:ZnSe Laser Exited by Diode Side-Pumped Er:YAG Laser

Round 1

Reviewer 1 Report

 

The paper is devoted to experimental study of mid-IR solid-state lasers based on promising Fe:ZnSe active medium. The results are interesting and significant. They are also supported by numerical simulations. I believe that the paper suitable for publication in Photonics, but I have a few comments and suggestions to the authors.

1. The authors do not discuss parasitic thermal effects that can arise in such systems and lead to beam degradation, thermal lensing, etc. It would be useful to discuss if such effects important here or not.

2. The authors describe in detail experimental schemes and report their parameters such as reflectivity, distances, etc. It should be commented, are these values optimal or the authors used available for them (non-optimized ) components/configurations.

3. Numerical model and numerical results are presented only in section Discussion, which seems a bit strange. I suggest to the authors to put them in a subsection of the section Results.

There are typos and inaccuracies in the text, for example:

·       In Table 1, the definition for tau1 is written in Russian: “t1 Время жизни верхнего уровня ионов Er 85 μs [14]”.

·       In paragraph Author Contributions, should “V.I” be changed for “V.K.”?

 

 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 2 Report

The authors reported on a Fe:ZnSe laser exited by diode side-pumped Er:YAG laser, achieving a pulse energy of 53 mJ with a slope 9 efficiency of 42% relative to absorbed pump energy. Pulses with a duration of less than 200 ns and an energy of ~ 1 mJ were obtained from the Fe:ZnSe laser with a repetition rate of up to 50 kHz. Some of the results obtained are interesting. This manuscript could be accepted in Photonics after minor revisions.

1.     The authors are suggested to give more description of the transmission spectra of Fe:ZnSe crystals in Fig. 2.

2.     Why the Intensity of Er:YAG trace are fluctuant in Fig.3?

3.     The properties of the proposed laser and fiber lasers mode-locked by saturable absorbers [e.g., Laser Photonics Rev. 16, 2200386 (2022)] should be compared in the revised manuscript.

4.     The authors provided output pulse energy versus LD current and absorber pump pulse energy. However, the changes of output pulse width and LD current should also be given. 

The authors reported on a Fe:ZnSe laser exited by diode side-pumped Er:YAG laser, achieving a pulse energy of 53 mJ with a slope 9 efficiency of 42% relative to absorbed pump energy. Pulses with a duration of less than 200 ns and an energy of 1 mJ were obtained from the Fe:ZnSe laser with a repetition rate of up to 50 kHz. Some of the results obtained are interesting. This manuscript could be accepted in Photonics after minor revisions.

1.     The authors are suggested to give more description of the transmission spectra of Fe:ZnSe crystals in Fig. 2.

2.     Why the Intensity of Er:YAG trace are fluctuant in Fig.3?

3.     The properties of the proposed laser and fiber lasers mode-locked by saturable absorbers [e.g., Adv. Opt. Mater. 11, 2300124 (2023); Laser Photonics Rev. 16, 2200386 (2022)] should be compared in the revised manuscript.

4.     The authors provided output pulse energy versus LD current and absorber pump pulse energy. However, the changes of output pulse width and LD current should also be given. 

Author Response

Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

The manuscript reports on an Fe:ZnSe laser emitting in the mid-infrared (MIR) band around 4 microns.  The laser is pumped by an all-solid-state Er:YAG laser (i.e. diode-pumped).  The laser is operated at liquid nitrogen temperature and at room temperature with three different cavities; state-of-the-art performances are reported.  At room temperature, Fe:ZnSe is both used as the laser material and as passive Q-switch.  Detailed investigation of laser dynamics is compared to simulations with a rate-equation model and a very good agreement is found.

Overall the content of the manuscript is interesting to read and the results are comparable or superior to prior art in terms of performances.  The manuscript is likely to impact future research in the field.  The manuscript is very well written

Minor corrections are suggested:

- The caption and drawings of Fig. 7 should be on the same page (they are on p. 6-7 in the submitted manuscript).

- Ideally the entire content of Table 1 should be on one page.

- Table 1, line 10.  Please translate the text in English

- Table 1, lines 12-13 (meaning of tau2 and tau20).  How could the lifetime of the upper level of Fe ions be longer than their radiative lifetime by three orders of magnitude?

- Line 232.  Should the text refer to Figure 7B instead of Fig. 8b?

Author Response

Please see the attachment.

Author Response File: Author Response.docx