Modulated High Power and Narrow Pulse Width Laser Drive Circuit for Lidar System
Round 1
Reviewer 1 Report
The authors present a simple and efficient method for generating peak power laser pulse (135W) of width less than 2ns at pulse per second of 400 kHz. This seems being a major improvement of state of the art. However, the state of the art and reference papers are very scarcely presented.
The authors shall give a broader presentation of the state of the art and reference papers. Please comparatively present (for example in a table) the principal methods for generating shorth pulse with high power laser in lidar applications for a better understanding of the main contributions of this paper.
The working principle of testing platform, figure 2, shall be described in more details and it shall be correlated with the circuit working stage description.
The model of the drive circuit discharging part, presented in figure 7, shows a 3D model. It will be more valuable, if the authors will present instead figure 7, a closed real photo view of the electronic circuit package used in experiments.
Please present figure 8 to 15 in higher resolution.
Please explain the negative discharge currents in figures 9 and 10.
Lines 257-259 "simulation model of the drive circuit was established. The inductance and resistance in the discharge circuit are mainly composed of PCB traces and the equivalent parameters of the laser diode." Please present the layout of simulation model and a description of the simulation tools and analysis techniques applied to get the results in figure 11.
More details about experiments and results shall be given. It is not clear if the experiments are performed on the test platform presented in figure 2 or another means and techniques are used. The results shall highlight the main contributions and the novelty of the proposed subject.
Conclusions shall be further improved to highlight the main contributions of the authors to this subject.
It is recommended to review the English grammar throughout the article.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
This paper introduces a laser drive circuit employing GaN FET.
- Could you please describe the novelty in your design? I don't see any key contributions.
- Could you please add a comparison table with other works to highlight your design?
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Good article describing interesting research. The manuscript needs improvement, and the reviewer has done due diligence suggesting improvements, generally to the manuscript presentation, not the scientific work.
- In the abstract, lines 10-12 are unclear. The specifications are clearly listed (nanosecond, >100W peak), but these sentences imply the pulse width must be reduced and the peak power must be increased without rationale for the modified specifications.
- Again in line 16, the notion is forwarded that laser pulse peak power is proposed without motivation for changing peak power beyond the stated specification.
- In lines 17-18 alternative specifications are given without expression about the efficacy of such modified specifications.
- Line 32: please stipulate that higher peak power is better and smaller pulse width are better or worst.
- Line 43 has rough grammar clouding the sentences intended meaning.
- In lines 8, 60, 179, and 395 the work is referred to as a “paper” imparting the impression to the reader of being a mere college student’s course paper. The reviewer recommends using a more professional term, e.g. manuscript, treatise, article, monograph, etc.
- Section 2 is generally very well done. The narrative tone well prepares the reader for more in depth investigations of section 3, albeit the reviewer cautions the authors about clusters of acronym and variables that make parts needlessly challenging for the readers.
- Line 67 indicates a comparison was made to contemporary methods, but such comparison seems to be missing. Correcting this omission is as easy as adding citation to other research and making comparisons in verbiage, and this augmentation will provide the “broadest possible” language requested in the manuscript’s template for the abstract and conclusions (i.e. percent difference compared to the other results).
- The text in figure 1 is blurry.
- Line 77-78 claims the rationale for using inductor current limiting will be explained in detail later (in what sections?), but the phrase “inductor current limiting” does not appear again anywhere in the manuscript. The inductor and it’s current limiting are discussed in detail but nonetheless a justifying rationale for the choice made in lines 77-78 remains elusive. Please state the rationale(s) for the choice.
- Lines 104-105 contain the claim the method of differentiating the capacitor voltage is “mentioned later”. In what section? Presumably section 3 (?) as witnessed in an equation, figures, and verbiage.
- Please explain why the control signal cannot achieve a sufficiently small pulse width in lines 83-85. The statement seems to be directly contradicted by the subsequent sentences describing how the control circuit’s capacitor can be chosen sufficiently small to obtain a nanosecond pulse width.
- Define acronyms on first use (e.g. lines 91-92), and it is a courtesy to the reader to spell out the acronyms occasionally to preclude the requirement the reader flip back and forth through the pages to remind themselves of acronym definitions. One author technique (provided merely as a suggestion) is to look at a page of text slightly not focusing your eyes to notice that large, capital letters acronyms and variable stand out amidst the regular text. With such a view, places where reading has been made difficult become rapidly apparent, since groupings of many acronyms and variables will make those sentences and paragraphs more challenging to read.
- Please define “the ps level” used in line 95
- The intended meaning of lines 99-100 are unclear.
- The use of “will be discussed later” is slightly frustrating. Where later? Addition to the sentence of the section being referenced would permit the readers to peek ahead foreshadowing their interests in the manuscript.
- The text size in figure 2 is illegibly small. As a guide, try to never let text inside figures be smaller than the figure caption (often the smallest text size permissible in the manuscript).
- Q1 is not first defined before use in figure 2 and line 120. Especially since there are only one of each device in the figure, periodically referring to the devices by names rather than variables can be done without loss of clarity amplifying sentences such as “…When Q1 is turned off, U1 charges C1 through L1 and D1, the charging current path is 127
- shown in Fig. 4.…”
- Figure 5 is illegible and relays no information due to insufficient text size.
- Please list the parasitic parameters in paragraph 2.3, lines 148-151.
- Please improve the clarity and text size of figure 7 to make the features legible to the reader (particularly consider the usefulness of black-and-white printed copies of the manuscript).
- In line 208, if you assert “normally”, please cite references validating the ubiquitous nature of the technique. Otherwise, replace “normally” with a less definite term, like “often”
- Please add figures of merit to establish the comparison in figure 8, e.g. mean and standard deviation of residual or difference. Consider such quantitative comparisons for figure 10 (and others).
- In section 4, please clarify if experiments were performed on laboratory hardware of are merely simulations by including a photo of the experimental setup. Alternatively, modify the references to “experiments” to clearly indicate they are simulations.
- In the conclusions, please revert to using broadest possible terminology. In particular the final sentence uses very specific terminology and will reduce readership in instances where potential readers (as they often do) preliminarily scan the manuscript’s abstract and conclusions to ascertain whether or not to continue reading the entire manuscript. Very broad terminology in the final sentence of the introduction (line 67) implies a comparison was made to existing research. The reviewer recommends using such broad terminology in the concluding discussion as percent difference compared to the existing research claimed in line 67.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Thank you for the feedback and improved version of paper. Your answers intrigued to few more questions:
You specified that "negative discharge current waveforms in Fig. 9" are caused by measurement noise. They seems being quite important, ca 15% of current discharge peak. How much do you estimate the positive current discharge peak being affected by the measurement noise?
Please present in table or on a new figure with the simulation circuit, the parasitic parameters values determined for each component. Please explain in section 4 how each of the acquired parasitic parameters are used in the calculations.
Thank you for your feedback.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 2 Report
The authors responded to all the comments.
Author Response
Reviewer 2 thinks that the English style of this manuscript need to improve.
And the editor tells us in the E-mail that "We will provide English editing service if paper acceptance, which has included in APC."
