High-Power, Narrow-Linewidth, Continuous-Wave, Thulium-Doped Fiber Laser Based on MOPA

Round 1

Reviewer 1 Report

The Authors experimentally demonstrate a high-power, narrow linewidth, continuous wave, thulium doped fiber laser based on MOPA with a power of 26 W a FWHM of 0.05 nm. Here, my comments to the manuscript:

-          The Authors should discuss about the novelty of the proposed laser.

-          In the Section 2, the Authors should discuss about the laser operation and the requirements that have driven the choice of the devices on the market.

Author Response

Thank you for the comments!

Author Response File: Author Response.docx

Reviewer 2 Report

In the following paper, entitled, “High-power Narrow-linewidth Continuous-wave Thulium-doped Fiber Laser Based on MOPA” the Guan et al, proposed and demonstrated a high-power, narrow-linewidth, continuous wave, thulium-doped fiber laser (TDFL) based on master-oscillator power-amplifier (MOPA). The results are interesting. I would recommend the manuscript to be accepted after incorporating following comments.

 

 

1.     The author should include literature review belongs to thulium-doped fiber laser (TDFL) based on master-oscillator power-amplifier (MOPA) as well as the clear novelty statement in the introduction section.

2.     What’s the FBG core/clad diameter of input and output port?

3.     How the length of TDF was chosen?

4.     Why the TDF in the pre-amplifier stage has no cooling system? Does its effects on the stability of overall system as shown in Fig. 7.

5.     For better understanding, I would suggest to include the schematics of Forward/backward and two-end pumping.

6.     Replace Fig. 1(a) with Fig. 1 in caption.

7.     Image quality needs to improve as resolution seems to be very poor and difficult to read

 

Author Response

Thank you for the comments!

Author Response File: Author Response.docx

Reviewer 3 Report

The authors experimentally demonstrated a 26 W all-fiber narrow-linewidth thulium-doped fiber (TDF) MOPA at central wavelength of 1940.33 nm with 3 dB spectral bandwidth of 0.05 nm. The output power was limited by the available pump source. The idea and realization are well-known common, and achieved results are not very impressive. But in general, I do not mind the publication of the paper. It is likely that it may be useful to someone as a guide in the development of a similar system. I suggest to the authors revised the following points.

·       The authors reported that to build Tm-doped fiber (TDF) MOPA, they used components with certain parameters (2-m long TDF for a master oscillator, a pair of fiber Bragg gratings (FBGs) with reflection ratios of 99% and 10%, and 4-m long TDF for a amplifier). But it is not clear why these parameters were chosen. Was there any numerical or experimental optimization, or were there estimates for the required parameters (lengths and reflection coefficients)?

·       The quality of Figures is too low and should be improved (especially for Fig. 1 and Fig. 7).

·       Figure caption, line 65: “Figure 1. (a) Absorption spectrum of thulium ions”. “(a)” should be deleted.

Author Response

Thank you for the comments!

Author Response File: Author Response.docx

Reviewer 4 Report

The authors realized the high-power Tm-doped fiber amplifier in amplifying the 1940-nm narrow bandwidth laser. I think the following questions must be concerned

1.  The spectral bandwidth is 0.05 nm. Is it possible just becasue of the highest resolution of the spectrometer is 0.05 nm?

2. There are typos need to be corrected. For example, on page 1, 1st paragraph, the fourth line from the bottom, there is the ‘-’ missing there. It should be 2-um.

3. It seems the pictures are not clear? The authors need to make sure they use the correct format.

4.  I believe more novel points need to be clarified in this manuscript. The high slope efficiency of the Tm-doped fiber amplifier is impressive. However, more novel points need to be presented to make the manuscript published.

5. The English of the manuscript needs to be polished. Efforts needs to be done here.

 

Author Response

Thank you for the suggestions！

Author Response File: Author Response.docx

Round 2

Reviewer 4 Report

I believe the manuscript can be accepted now.