Which domain? or What is the name of our research field?

When preparing this blog, the question of which domain to pick was of course an important one. The obvious choice would be to take the name of the research field because after all it is a blog for the research field. But then, what is the name of our research field? So I did a bit of research. Here is a list on names that are used in literature:

  • Microresonator frequency combs
  • Microresonator-based frequency combs
  • Kerr frequency combs
  • Microcombs
  • Parametric combs

Not listed are short versions where “frequency comb” is just “comb”. If you work in the field, you have probably come across these names for the field and used one or another. I used to use “microresonator frequency comb” but I was not sure about this choice and I do not like the current situation where there are many different names actively used. And as it is just a convention after all and conventions are pretty much just majority decision on things, I decided to go more into depth in order to decide which name and which domain to pick.

First stop of this quick research detour were the big search engines, Bing and Google. The number of hits (on 20 Feb 2016) for the most common names are the following:

Search engine “Microresonator frequency comb” “Kerr frequency comb” Microcomb “frequency comb”
Bing.com 1790 2930 1050
Google.com 1950 3730 1260

While one can argue about the quality of the results, “Kerr frequency combs” seems to be the consistent winner here. One thing that also became clear is, that “microcomb” has another usage, that is documented here. This was sort of a spoiler for this name and also it performed the worst. Therefore the two remaining contenders were “Microresonator frequency combs” and “Kerr frequency combs”.

In the next steps I focused on the existing body of scientific literature, going from coarse searches to some more detailed studies. For the general searches I used Google Scholar and Scopus. Again, I did not check every hit but the at least the first few hits did indeed cover the research field. The result was the following (21 Feb 2016):

Search engine “Microresonator frequency comb” “Kerr frequency comb” Microcomb “frequency comb”
Google Scholar 115 239 153
Scopus 50 124 22

And for Scopus I also did a quick plot of the numbers over the publication year:

Scopus hits over years
Hits for the stated search terms (including quotation marks) in Scopus with the default setting (article title, abstract, keywords) over the year given by Scopus.

Also here “Kerr frequency comb” comes out ahead. Looking through some of the main work published in the field it is also one of the favorite names. In particular the orginal work uses the name “Kerr combs” in the body of the paper. Some of the earlier works from the group of Alexander Gaeta and Michael Lipson used the name “parametric frequency comb” but this name did not find traction and also later work from the same group uses rather “microresonator-based frequency combs”. Papers that come from the group at NIST, Boulder (Scott Diddams, Scott Papp) use the name “microcomb” in the body of the work. For the title, however, “microresonator(-based) frequency combs” seemed to be preferred by them as well. The work from the group of Andrew Weiner seems to use “Kerr comb” in the body and also sometimes in the title, but “microresonator frequency comb” is present in the title as well. The group of Tobias Kippenberg (where I am working) uses “Kerr comb” as well as “microresonator-based frequency comb” in the title and body of the papers. The group of Kerry Vahala uses “microcomb” in the body. As it becomes clear, there is no winner here. It seems like most of the bigger groups in the field use a mix of multiple names which can change within the paper and from paper to paper.

To get an idea of the opinion of fellow researchers I did a quick Doodle survey which resulted in the following outcome:

Option Votes
Microresonator frequency combs 1
Microresonator-based frequency combs 1
Microcombs 0
Kerr frequency combs 7
Microresonator Kerr frequency combs 2
Parametric combs 0

Again, “Kerr frequency combs” is the clear winner here even with a pretty large margin. That settled for me the point. Most results agreed that Kerr frequency combs is apparently the most used and most liked name for our research field. So this is how it became kerrfrequencycombs.org and this is the name that is going to be used here for the the field and the technology as well. Whether you agree or disagree with this choice, let us know in the comments below (which require a login and are only visible after login).

One other note on the usage of multiple names for the same field: For someone not working in this field, the variety of names is most likely quite confusing as it is not obvious why a “Kerr frequency comb” and a “microresonator-based frequency comb” should be one and the same thing. Additionally, it is difficult to reference something when even the community does not agree on one name.

CC BY 4.0 This work is licensed under a Creative Commons Attribution 4.0 International License.

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