Multipulse Optical-Rectification-Based THz Source for Accelerator Applications

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The authors present the generation of single- and multi-cycle THz generation. A conversion efficiency of 0.78%, 49 uJ THz energy has been achieved. It might be of interest in material and accelerator science. I suggest the manuscript for publication after correction.

My specific comments are presented below:

1.       Please give detailed info concerning the grating used in the experiment, grating lines, and efficiency.

2.       In Figure 11, could the author plot the retrieved pulse train and compare it with the EOS in Figure 12?

3.       In Figure 6, both cross-polarized and balanced detection shows a small post-signal after the main peak. Why do they show up at different delays from the main peak?

4.       There is no information about CCD sensor size in figure 7.

 

5.       Please check the figure caption of Fig. 12, why a pulse train is used for the EOS?

Comments on the Quality of English Language

There are minor typoes, please correct them.

Author Response

Thank you for the comments.  

1. We added a sentence in section 2.2 that explains the grating parameters.
2. We added the UV line data to Fig. 12 which shows good agreement. Thank for this suggestion.
3. We noticed the x-axis scaling was off by a factor of 2. This has been corrected. The second peak as well as pulse lengths now match between crossed and balanced detection. Thank you for pointing this out.
4. We added transverse dimensions in Fig. 6 that showcase the THz spotsize on the ZnTe. The CCD sensor size should be irrelevant as we are imaging the crystal onto the sensor.
5. The pulse train in the probe path is not chosen but a relic from generating pulse trains before our setup since the probe pulse and and pump pulse are obtained from the same laser system. We elaborate this in section 4.3 and rewrote it to make this problem clearer. To our knowledge, it is not possible to reduce IR ps-scale pulse trains down to single pulses.

The paper was re-read, and some typos have been corrected.

Please ignore the attached pdf file. Once uploaded, I couldn't delete it.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In the manuscript "Multi-pulse optical rectification based THz Source for Accelerator Applications" the authors describe the setup they have outlined and mounted in order to generate high-power and narrow bandwidth THz pulses for applications in the field of accelerators.

The text is very well written, full of details and with very clear and informative pictures. The theoretical framework is also clearly presented. I have really no remarks to add ecxept for one: the lithium niobate technique for producing THz is surely not something new, and therefore the novelty of the present work lyies entirely in the idea of using split pump pulses in order to increase the spectral weight on a specific frequency range, effectively narrowing the THz spectrum and therefore "concentrating" the energy only where it is needed. Anyway, the authors themselves acknowledge that this can be obtained only at the cost of reducing the overall efficiency, due to several effects which are honestly described in the paper. For this reasons I frankly doubt that the proposed method will actually succeed in obtaining what the authors would like to achieve and that maybe other routes could be explored such as THz generation in diamond and/or other new experimental techniques. Nonetheless, I think the work is scientifically sound and it deserves to be published in its present form.

Author Response

We would like to thank the referee for his comments and consideration for publication. 

To our knowledge, diamonds as an optical rectification source produce higher frequency radiation at much lower efficiencies but we will be looking forward to any new developments in this type of source.