Nanotubes in Chitin Mode Locker for Passive Mode−Locked Fibre Laser in 2.0 µm Region

Round 1

Reviewer 1 Report

In this work, a CNT-embedded-in-chitin composite was used as an SA and incorporated into the cavity to build a mode-locked THDFL.  The central wavelength of 1908.53 nm with a spectral bandwidth of 3.59 nm and an output power of 0.2 mW was measured during mode-locking of the laser. The shortest pulse width of 1.1 ps and a repetition rate of 16 MHz was obtained too. What I am interested in is the authors have used chitin as the hoster for CNT. This kind of composite is a relatively stable solid with a medium damage threshold, compared with the other SA materials, especially, CNT-related materials. However, it seems the transmission rate of chitin for the laser beam is not too high. And when CNT was added into chitin, the transmission rate becomes much lower. The authors might want to reduce the amount of CNT, so as to increase the transmission rate. Anyway, this composite design was good, but still need to be improved.

Author Response

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Reviewer 2 Report

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Reviewer 3 Report

The manuscript presents a new SA material (CNT-chitin) for fiber laser mode-locker. The authors evaluated the performance of a THDFL based on this new SA material, and reported parameters such as output power, pulse duration, repetition rate, spectral band width, and pump power range, etc. There are some areas that can be further improved to enhance the overall quality of the manuscript, and I recommend minor revisions addressing the following comments:

1.     In Figure 4 (b), there is a blue square that appears way off the red fitting line in the bottom left corner. It would be helpful to explain the origin of this outlier and whether you have repeated the same measurements to confirm the data.

2.     Please include the output power in Table 1, as it is a important parameter deciding the laser’s possible applications. Since the pump power is already listed in Table 1 and the output power of the CNT-chitin fiber laser is presented in the conclusion, I think it would be valuable to compare the output power for all of these lasers.

3.     It may be necessary to show the beam profile of this laser because beam profile is also an important performance factor. A poor beam profile could limit the laser's application.

4.     The authors claimed that the mode-locker works normally in a pump power range from 203 to 228.6 mW. Please provide specific data to support this claim, such as the OSAs or pulse trains at 185, 205, 225, and 245mW pump power.

5.     There are several abbreviations used before stating their full names:

a.     WDM in figure 4. The full name firstly stated after this figure in line 241.

b.     LD in figure 5.

c.     TDF in figure 5. By the way, I think it should be THDF.

d.     SMF in line 247.

6.     Consistency issue. The wavelength should be 1550 nm in line 238 and 242, or the wavelength should be 1560 nm in figure 5.

7.     Please provide the brand name and model of your 1550 nm diode laser.

8.     Figure 5 is identical to Fig 7 in Ref 28. Copyright transfer approval may be needed, even though these two articles are from the same research group.

Author Response

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