Low-Threshold, High-Power On-Chip Tunable III-V/Si Lasers with Integrated Semiconductor Optical Amplifiers

Round 1

Reviewer 1 Report

The authors succeed in demonstrating III-V/Si co-integrated tunable laser with low threshold, narrow line-width, and wide wavelength tuning range. Moreover, optical output power is further boosted by on-chip SOA, thereby increasing the usabilities of the integrated devices in different application domains. This paper has sufficient amount of literature coverage, and is clearly written, well organized.

Author Response

We would like to thank the reviewer for reviewing the manuscript and for providing his positive feedback. The reviewer has not made any suggestions/remarks to improve the manuscript, suggesting that the manuscript can be published as is. 

Reviewer 2 Report

This article reports a widely tunable laser co-integrated with a semiconductor optical amplifier in a heterogeneous platform. The key achievement is the compactness of the device which helps in reducing the power consumption. In my opinion, the results are publishable but the manuscript is difficult to follow because of the errors in cross-referencing and captions of the figures. So, the paper should only be published if the quality of the manuscript is improved. I am pointing out some of the problems below:

• There is an inconsistency in reporting of the center wavelength which can cause confusion to the readers. The center wavelength of 1549nm is reported in the abstract in contrast to 1550nm on Page 2, line 90.
• Page 3, Figure 1: A scale bar should be added to the figure in order to give the reader an idea about the thicknesses of different material layers and the size of the mode. A legend mapping the used colours in the 3D schematic to the materials would be helpful.
• Page 5, Figure 2: Please add scale bars to the calculated modes in the insets.
• Page 5, line 186: Figure 2(c) is cross-referenced in the text but there is no Figure 2(c) in the manuscript. Figure 2 only has (a) and (b).
• Page 6, Figure 3, Caption: It is mentioned in the caption that ‘(c) and (d) show the V-I characteristics of the thermal heaters’ but I am unable to find a V-I characteristic in Fig 3(d). In my opinion, the authors meant (b) and (c) instead of (c) and (d). Please add scale bars to the calculated modes in Fig 3(a).
• Page 6, line 237: Right below Figure 3, it is mentioned that ‘Figure 2(c) shows the V-I curve’. I can only see the V-I curve in Figure 3(c) and there is no Figure 2(c).
• Page 7, line 284: Again problem with cross-referencing of Figure 4(d). I am unable to see the measured lasing spectra in Figure 4(c). I think the authors meant Figure 4(d) here.

Author Response

Thank you very much for the positive feedback. We have modified the manuscript accordingly (see the word document for a detailed list of changes in the manuscript).

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The authors have addressed my concerns and the manuscript is in a better form now. The manuscript should be accepted in the present form.