Fabrication of Lensed Optical Fibers for Biosensing Probes Using CO2 and Femtosecond Lasers
Round 1
Reviewer 1 Report
The article describes a novel method to manufacture lensed optical fibers using CO2 and femtosecond lasers. First, they describe the theoretical parts and the simulations, and after they present their experimental results.
In general, the writing should be improved because it makes it difficult to follow and understand.
- Abstract needs to be rewritten, and English improved.
- The introduction could be more extended, maybe mentioning a bit more about the background and the scope of the research (in my opinion, one paraghraph is not enought).
- There is no method section - methodology is explained in the results part.
- The results section is fine.
- The conclusion should be extended, maybe including future directions of the research.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The manuscript describes the fabrication of lens on the tip of the fiber by melting the tip with CO2 laser and cleaving with FS laser. The manuscript is well formatted and describes the process and mechanism very well. The technique may provide alternative to other conventional methods for forming fiber lens for biosensing applications. However, I would suggest authors to provide a comparison table between conventional methods such as arc discharge and others vs this technique in terms of repeatability, precision, manufacturing complexity, cost/time etc.
Few minor questions and comments to authors:
- What is the beam size at the tip of the fiber while melting using CO2 laser? Do you use any focusing optics? If so, what is the beam size at focal point? Is it smaller or larger than the diameter of the fiber itself? How good the alignment of optical axis of laser beam and the axis of the fiber needs to be for the symmetric lens profile about the axis?
- Authors say, this technique can be used to make lenses of desired focal length. However, the focal lengths mentioned here are 300 micron and more. What is the range of focal lengths that can be fabricated with the same ease? For example, can you reliably fabricate a lens of focal length 10 micron with this method? If yes, what is the reproducibility? If not please describe the complexities that may involve.
- Please improve the quality of images. Fig. 2 look like stretched in horizontal direction without maintain the aspect ratio. Figure of Fig. 4 are hard to see the labeling. Using magnified images and proportionate font size would help to read them clearly.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
The manuscript submitted by Lim et al. reports on the fabrication of lensed optical fiber with desired focal length using CO2 and femtosecond laser. The topic is definitely of interest and suitable for the Applied Science journal and the manuscript is well written. I would suggest considering the following comments.
Comments/questions:
1. Figure 2: the unit of the color coding is missing.
2. Figure 4: the scale bar is missing. It is hard to tell the difference between the 3 figures.
3. Section 3.3: the mirror reflection method and the knife edge method need more details in your setup
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Authors have made substantial changes and I believe that the article has improved a lot and it can be published in the present form or maybe after minor edition changes.
