Cylindrical Rod Phosphor Structure for Laser-Driven White Lighting
Round 1
Reviewer 1 Report
This paper describes the use of commercial substances, silicon and phosphors, to produce a rod that, when illuminated with a blue laser, that will excite the phosphors, they will emit light (yellow for yellow emitting phosphors or other color for others phosphors). It is difficult to understand the usefulness of this work that contains no scientific content and solve no technical difficulty. For example, the coupling of the laser light with the rod was not investigated. Indeed, a similar system, but with a much better performance, can be obtained used a visible laser (much more cheaper and efficient than the blue) coupled with a plastic optical fiber (much more cheaper and efficient that the silicon rod). The objective and the figures of merit of the proposed systems compared with others should also be discussed.
Author Response
Attached herewith please find the "Authors responses to the Reviewer Comments" and revised manuscript.
Author Response File: 
Author Response.doc
Reviewer 2 Report
The manuscript reports on the fabrication and testing of a cylindrical rod phosphor structure for laser-driven white lighting using commercial yellow and red phosphors. In general, the manuscript is well written and structured, and clearly presents the work motivation, engineering arguments, and characterization methodology.
Questions:
Was a ray optics simulation or more stringent light propagation analysis conducted to determine specific dimensions of the cylindrical rod phosphor design?
How the surrounding transparent layer thickness around the central cylindrical rod was determined to be 1 mm?
Was the central cylindrical rod facet polished before coupling the pumping blue laser?
What was the typical central cylindrical rod surface roughness before covering it with a transparent layer? Was efficiency of light coupling to the transparent layer considered?
Was the cylindrical mold filled with transparent gel under the pressure? Was the transparent layer free of micro/nano air bubbles/voids?
Was the cylindrical rod phosphor structure tested under various LD power conditions? The reported results are for 350mA whereas the LD maximum forward current rating can be 1.5A? How does the cylindrical rod phosphor perform with increased internal temperature due to high power excitation?
Were the spectra intensity in Fig.6 normalized to the max of visible emission? We have noticed that in Fig.6(c) there is an artificial feature seen at ~480nm which might result from stitching two parts of the spectra after renormalization of the longer wavelength parts. If so, this fact must be mentioned in the manuscript, if now please explain the observed spectral featured at ~480nm.
In conclusion, the manuscript presents a rather straightforward concept of a cylindrical rod phosphor structure for laser-driven white lighting. We recommend that the authors enhance the engineering-specific contents and parameters to validate the design, especially at higher LD excitation conditions.
Author Response
Attached herewith please find the "Authors responses to the Reviewer Comments" and revised manuscript.
Author Response File: Author Response.doc
Reviewer 3 Report
A manuscript concerning the application of rod phosphor material for generation of white laser has been presented. The subject is interesting. There are some points which should be mentioned by the authors before a further consideration as mentioned below:
1. Figure 3 needs scale bar. In addition, Figure 4 can be merged with Figure 3.
2. Figure 6 should be merged with Figure 5.
3. The introduction section is very long and should be shortened.
4. Is the “Rod Phosphor” is really “Rod Bronze Phosphor”? please clarify.
5. Could the authors give some further evidence relating to the blue light absorption? Some optical characterizations are required for this purpose.
Author Response
Attached herewith please find the "Authors responses to the Reviewer Comments" and revised manuscript.
Author Response File: Author Response.doc
Round 2
Reviewer 1 Report
In order to assess the present system it must be compared with others! At least, the performance of the proposed system should be compared with another where the "blue laser+phosphors" is replaced by a visible light laser. Indeed, the questions that must be answered is why use a "blue laser+phosphors" if the same effect can be obtained with only a visible laser (or one emitting at the phosphor wavelength)?
Author Response
Please find attached for more details.
Author Response File: 
Author Response.pdf
Reviewer 3 Report
The manuscript has been revised and now it can be considered for publication.
Author Response
Dear reviewer,
We would like to express our sincere thanks to the Reviewers for their recommendation and comments which have helped in substantially improving the quality of the proposed work. Finally, we appreciated the thorough reviews and positive response from you.
Best Regards,
Shang-Ping Ying
Department of Semiconductor and Electro-Optical Technology, Minghsin University of Science & Technology
E-mail address: sbying@must.edu.tw
