Compact 50 W All-Solid-State Picosecond Laser System at 1 kHz
Round 1
Reviewer 1 Report
I send here my opinion about the paper “Compact 50W all-solid-state picosecond laser system 3 at 1kHz” sent to be published in Appl. Sci.
This proposes a compact, high-power and high-repetition picosecond laser system which can deliver 50 ps pulses and powers of 50W at 1kHz frequency.
The manuscript is well written, with very detailed information about system configuration and characterization.
In this respect, I recommend the publications of the article in Applied Sciences as it is.
I have only one minor remark, authors to give in introduction a phrase with references of their previous work in the field, if any.
Author Response
Dear Reviewer，
Thank you very much for the reviewers' recognition of our manuscript entitled “Compact 50 W all-solid-state picosecond laser system at 1 kHz” (ID: 927949).This is my first paper about Nd:YAG picosecond laser, and the previous work of our group has been cited in the article.
Thank you very much for your comments and suggestions.
Reviewer 2 Report
Review for manuscript ID 927949, titled: “Femtosecond laser-micromachining of glass micro-chip for High Order Harmonic Generation in gases”. The manuscript presents Nd:YAG based amplifier system emitting pulses at 1 kHz and average output power of 6.5 W. They also demonstrate simulation results for possibility of further amplification of the pulses to 50 W. However, I do not understand the main purpose of the development of this laser. Below are my comments:
- Firstly, I would encourage the authors to improve the language of presentation. It needs major improvement.
- Introduction needs to be rewritten. The motivation of this work is not at all clear. What is the motivation of using this gain medium? What is the drawback of the current system in literature. Nd:YAG based lasers are well established technology and the authors should explain clearly the novelty of their work compared to the existing technology with proper references. In the current form, the references are not explained clearly.
- In line # 71, the authors claim more compact structure of their amplifier compared to other MOPA system but the claim is not backed up by any reference nor comparison of the foot-print of the amplifier is mentioned.
- In Section 2.1, the authors give very incomplete description of the picosecond oscillator. Also its not clear if the oscillator is home-built or commercial. If it's a home-built oscillator then I assume it must have been published separately and if its not published then more design details needs to be present.
- Since, this is a homebuilt design of the amplifier system, the reader would expect more details of the design consideration in the section 2.2-2.4. Currently, I feel there are many crucial details missing.
- Figure 2, contains only the Gaussian fit graph. The data points should also be there.
- Two figures are name numbered same as 2.
- The M2 figure (a) and (b) at two different power level is totally unnecessary. One figure is enough.
- Every picture of beam should be zoomed by cropping out the unwanted pixel area.
Typographical error:
- There should be space between each numbers and corresponding unit like instead of 1kHz it should be 1 kHz. Additionally, at many places μs is written as us.
- Figure 1 looks too complicated. I would suggest using square boxes in background of each major parts of system like oscillator, and each amplification stage.
- Line #88 units are not right. 3x3x40mm2 ? 0.3 at % ??
- Line # 100, ‘’The beam quality was about 1.3…’’, should be “the M2 value in the x and y direction…“
Author Response
Dear Reviewer:
Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Compact 50 W all-solid-state picosecond laser system at 1 kHz” (ID: 927949). The comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to the researches. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewer’s comments are as flowing:
1、- Firstly, I would encourage the authors to improve the language of presentation. It needs major improvement.
- Introduction needs to be rewritten. The motivation of this work is not at all clear. What is the motivation of using this gain medium? What is the drawback of the current system in literature. Nd:YAG based lasers are well established technology and the authors should explain clearly the novelty of their work compared to the existing technology with proper references. In the current form, the references are not explained clearly.
- In line # 71, the authors claim more compact structure of their amplifier compared to other MOPA system but the claim is not backed up by any reference nor comparison of the foot-print of the amplifier is mentioned.
Response to the comment: The introduction has been revised, the main motivation of this paper is to simplify the amplifying structure of picosecond high-power lasers by increasing the output power of each amplifier. In the current systems, the output power of the regenerative amplifier stage is usually about 2 W at 1 kHz. In order to achieve higher output power, three or more traveling-wave amplifiers are usually required. So as to achieve a compact structure, a regenerative amplifier that can output higher power at 1 kHz is designed in the laser system. The output pulse can be amplified to 50 W at 1 kHz after passing through an end-pumped traveling-wave amplifier and a side-pumped traveling-wave amplifier. So this laser system has simpler structure.
2、In Section 2.1, the authors give very incomplete description of the picosecond oscillator. Also its not clear if the oscillator is home-built or commercial. If it's a home-built oscillator then I assume it must have been published separately and if its not published then more design details needs to be present.)
Response to the comment: Section 2.1 adds a more detailed description of the oscillator. The radius of curvature of the mirror and output coupler mirror have been given a detailed description. Details have been marked in the manuscript.
3、Since, this is a homebuilt design of the amplifier system, the reader would expect more details of the design consideration in the section 2.2-2.4. Currently, I feel there are many crucial details missing.
Response to the comment: Section 2.2 adds a more detailed description of the regenerative amplifier. The radius of curvature of the mirrors have been given a detailed description. The details have been marked in the manuscript.
4、Figure 2, contains only the Gaussian fit graph. The data points should also be there.
Response to the comment: Figure 2 is modified to include the measured data.
5、Two figures are name numbered same as 2.
Response to the comment: We are very sorry for my negligence, the numbers of figure 4 and figure 3 have been corrected.
6、The M2 figure (a) and (b) at two different power level is totally unnecessary. One figure is enough.
Response to the comment: Figure 2 only retains the beam quality with the output power of 6.5W.
7、Every picture of beam should be zoomed by cropping out the unwanted pixel area.
Response to the comment: All pictures of beam have been zoomed by cropping out the unwanted pixel area.
8、Typographical error:
- There should be space between each numbers and corresponding unit like instead of 1kHz it should be 1 kHz. Additionally, at many places μs is written as us.
- Figure 1 looks too complicated. I would suggest using square boxes in background of each major parts of system like oscillator, and each amplification stage.
- Line #88 units are not right. 3x3x40mm2 ? 0.3 at % ??
- Line # 100, ‘’The beam quality was about 1.3…’’, should be “the M2 value in the x and y direction…“
Response to the comment:
-We are very sorry for my incorrect writing, a space is added between the number and the unit. And typographical errors have also been corrected.
-According to your suggestion, Figure1 adds background color make it easier to read.
-The description of the crystal has been revised to: The crystal in the cavity was a 0.3 at. % Nd-doped YAG crystal with a size of 3 x 3 x 40 mm3.
-According to your suggestion, the description of beam quality has been revised to: The M2 value in x and y direction were 1.327 and 1.445 respectively with the output power of 6.5 W.
We appreciate for Reviewer's warm work earnestly, and hope that the correction will meet with approval.
Once again, thank you very much for your comments and suggestions。
Reviewer 3 Report
The authors Yang Shuaishuai et al show in their letter a high power 1 Khz 1064 nm laser system. It consist of a ND:YVO4 oscillator and a home –made regenerative amplifier. They show that they overcome the limitation of thermal lens effects and demonstrate an output of 6.5W with remarkable beam quality. They use a non-axial pumped crystal to increase the power to 50W.
Unfortunate the authors do not give any information of the laser pulse duration of the beam when it has passed the final amplification state. The beam profile looks remarkable good. The authors also show how to obtain an equal phase retardation by passing the beam 2 times to the crystal. The article very technically but very well written. I recommend the publication. However, I want suggest two points.
Fig 1. Please write in the capture of figure 1 a description of all optics elements. It is not very clear what OC means. I suggest to underlay in different colors the oscillator, the regenerative amplifier and the final side pumped amplifier. This would give a certain order to the reader and the fig. would be easier to understand.
Please give information for the final pulse duration.
Author Response
Dear Editors and Reviewers:
Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Compact 50 W all-solid-state picosecond laser system at 1 kHz” (ID: 927949). The comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. The main corrections in the paper and the responds to the reviewer’s comments are as flowing:
- Figure 1 has added a background color to make it easier to read. And OC is an output coupler mirror. Also the detailed parameters of the oscillator are described in section 2.1.
- The information about final pulse duration: Because our autocorrelator can only measure pulses with a repetition rate greater than MHz, we are currently unable to accurately give the final pulse width. However, the spectrum of the oscillator we measured has the same width as the spectrum of the final output pulse. Material dispersion can be ignored, so the final output pulse width is approximately equal to that of the oscillator.
Once again, thank you very much for your comments and suggestions.
Round 2
Reviewer 2 Report
The comments and suggestions are implemented by the authors. I can recommend the manuscript for publication.
