Do What You Love and You Will Do Your Best” “

Donna Strickland in her laser laboratory on the day the Nobel Prize was announced.

“Do what you love and you will do your best” Donna Strickland needed a high-intensity laser pulse for her PhD thesis studies and, therefore, she developed the chirped pulse amplification. Kerstin Sonnabend

The Nobel Prize in Physics 218 was awarded “for ground- Why not? breaking inventions in the field of laser physics”. Arthur There was a number of reasons – one of them being self Ashkin shared one half “for the optical tweezers and focussing. Because the selffocussing length changes with their application to biological systems”. The other half the power not all of the pulse can focus to the same point in went jointly to Gérard Mourou and Donna Strickland space. Gérard Mourou, my supervisor at the time, came up “for their method of generating high-intensity, ultra- with the idea of the socalled chirped pulse amplification short optical pulses”. Donna Strickland is the third wom- to overcome the problem. We scrapped what I was working an to win a Nobel Prize in Physics. She was working on on before and started with the new technique. her PhD thesis in the group of Gérard Mourou when Was it a completely new approach? she performed the awarded research and she was the The technique was known from radar technology – and it first author of the decisive paper. was sort of all evolving at that time. It was already shown that the best pulse compression results were possible with Chirped pulse amplification was not the topic of stretched pulses. your PhD thesis. Why did you work on it anyway? Were there any detours? I was the only person in the group that was working on a Laser pulses can be stretched using different structures. highintensity laser project. I was supposed to measure the Oscar E. Martinez suggested different methods to receive ninth harmonic of a YAG laser impinging on a nickel plas the required negative groupvelocity dispersion in 1. ma. Therefore, I needed a short laser pulse with sufficient I used a special fibre which was donated to our group: energy but pulse compression did not work. 2,5 kilometres in a spool. To get both ends, I had to un

24 Physik Journal 18 (219) Nr. 2 © Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim Nobelpreis spool it and, unfortunately, it broke roughly in the middle. You changed your focus of research In the end, I was able to use 1, kilometres to stretch the after this important achievement? laser pulse. Well, I still used CPA for my studies but I did not want to be Did it work right away? part of the race to build the biggest and most intense lasers Yes, the pulse was stretched to 00 picoseconds. That was or to produce the shortest laser pulses. enough for our purpose although an ideal value would have Why not? been around one nanosecond. I like to work on small projects which I can do on my own What was your aim? or with one graduate student. Improving highintensity We wanted to show that the amplification did not destroy lasers to break the record is a tremendous team effort – the chirp. That is mandatory if you want to compress the and I am not into these big projects. signal after the amplification to its original length. You only How big is your group? get the desired highintensity ultrashort pulse if you are It is a small group – just a couple of graduate students able to perform this last step. and some undergrads. How did you show that? Are you still working in the lab once in a while? I had to determine the characteristics of the signal like Yes, I always tried to – but it became more difficult since its pulse length and its frequency for each step. And that October 2nd. worked out: The chirp was not destroyed by doing the am Do you remember the moment when you learned plification even past saturation. about winning the Nobel prize? However, CPA did not become your PhD project? It was around five o’clock in the morning. My husband, I was convinced that it was a good project but it would not Douglas Dykaar, answered the phone. We were both wor be enough for a thesis. For a thesis, you have to perform a ried in case something had happened to one of our children. scientific study. But I did not study chirped pulse amplifi They asked him whether Professor Strickland was available cation, I just realised it. My scientific study using CPA was and said: „Please stay on the line for an important call from about multiphoton ionisation – that was my thesis work. Sweden.“ During the next minutes I thought about it and Did you recognise the breakthrough then? said to my husband: “This has to be the Nobel prize. What We knew that we had found a way to get the most intense else could it be on this day and from Sweden?” light. Thus, it would be possible to study the interaction of But you were not sure until the official declaration? highintensity light and atoms in a way like nobody could No, I wasn’t. I did the work more than thirty years ago and have done before. But, at that moment, we didn’t know that was completely surprised. It is an amazing kind of feeling it would work for eye surgery or any of the other applica – and I just thought: Oh my God! tions. We just wanted to use it to change our understanding You were awarded together with your supervisor of how highintensity lasers interact with matter. Gérard Mourou… Were you involved in any of the further devel- … because I realised his idea. If Gérard would have won opments or applications? the Nobel Prize by himself I wouldn’t have been sur No, I chose not to work on chirped pulse prised – that would have been the usual way. I amplification as a postdoc. Since then, I guess we were both awarded because it was have mostly worked on basic nonlinear only the two of us to author the paper. optics. Besides spending less time in the lab what has changed for you?

Donna Strickland during her Nobel Lecture at the Aula Magna of Stockholm University. (Bildquelle: picture alliance / TT NYHETSBYRÅN)

Donna Strickland receives the Nobel diploma and the Nobel medal from Carl XVI. Gustaf, the King of Sweden.

I had dinner with the King of Sweden – and I met the Prime Do you see yourself as a role model for young Minister of Canada Justin Trudeau. In addition, I was in female scientists? vited to the Fortune Global Forum where presidents and A number of women, all the way down to elementary CEOs of world leading companies listened to me. That‘s schoolaged girls, contacted me and said that I am an in not usual for me. spiration. So, I guess there is something to that. However, Why? during the years, I worked with more men than women in I did the work more than 0 years ago and it didn‘t come to my group. For myself, it did not matter whether my super the attention of the general public. But now, after winning visors were male or female – I just wanted to do the physics the Nobel prize, it seems that there’s a stamp on me. And I was interested in. all of a sudden, everybody wants to talk to me. My life has Can you name any mentor who supported you changed completely. and your career in a special way? I did not have a special person who followed me through my career or served as a mentor. I would rather say I learned a lot from all my supervisors in the different stages of my Donna Strickland – CV in a nutshell career. How did you get your present position at the 1977 – 1981 McMaster University, Hamilton, Canada University of Waterloo? 1981 B.Eng. in engineering physics 1989 Ph.D. from University of Rochester, As a postdoc I worked at Canada’s National Research Rochester, USA Council with Paul Corkum who was one of the leading 1988 – 1991 research associate, National scientists for ultrafast lasers. That was the job I was eager Research Council of Canada, Ottawa, Canada to do. When the contract ended it was hard to find a new 1991 – 1992 physicist, Lawrence Livermore job. I was getting married and my husband, also a physicist, National Laboratory, USA worked at the Bell Laboratories at New Jersey. I took the 1992 – 1997 technical staﬀ , Princeton University, USA position of a physicist at Lawrence Livermore National Lab 1997 assistant professor, Univer- oratory near San Francisco. But I didn’t stay long because I sity of Waterloo, Canada wanted to live closer to my husband. Therefore, I became 2002 associate professor, University a member of the technical staff at Princeton University. At of Waterloo, Canada that point, we were both looking for other positions. When 2013 president of The Optical Society of America I got the position as an assistant professor at the University 2018 Nobel Prize in Physics, of Waterloo my husband followed me and took an industry full professor, University of job. Five years later, I became associate professor. Waterloo, Canada And you were still an associate professor before

University University of Waterloo you won the Nobel Prize?

Yes, because I did not bother to apply for the full professor And Maria Goeppert-Mayer? ship. I have had tenure for years – that was the important I think she was treated like an equal by her fellow scientists step. Being a tenured associate professor, I had the same but the universities or society as a whole did not see it that rights and duties as a full professor. To become a full pro way. When she did her research she later won the Nobel fessor I would have had to do some paperwork. Now, it Prize for she was not even paid. This is just mind-boggling worked out anyway. to me. Do you have any collaborators outside Canada Do you see any drawbacks for female and the United States? scientists today? I was supposed to go to China during the first week of Not really. In our part of the world, women have access December, but I had to cancel that trip because I had to go to higher education and if they want to progress in sci to Sweden for Nobel Week. So far, I have not collaborated ence there are no obvious barriers. However, the fraction with any European institute. My research does not rely on of women in physics in Canada is 15 to 20 percent. Perhaps, huge collaborations. there is a need for encouragement by society as a whole. Being the third woman ever to win the Nobel Are any of your children studying science? Prize, you are in the same line as Marie Curie and Yes, my daughter just started graduate school this year in Maria Goeppert-Mayer. What do you think the field of astrophysics. about that? Do you have any advice for graduate students? It is an overwhelming experience and I feel humbled be To graduate is a lot of hard work. You need to stay positive. cause my situation is not at all comparable to theirs. Do what you love and you will do your best. To find the In what sense? perfect job you also need a lot of luck. In our world, you Marie Curie is an outstanding scientist. She did amazing should be open for all opportunities. If you want to do aca research and won two Nobel Prizes in Physics and Chem demic research it seems to be mandatory to travel around istry. No one else was honoured that way. On top of that, the world and find your challenge wherever it is. As there nobody expected these accomplishments from a woman. are not so many jobs in academic research you might not It was before female suffrage, before higher education got live where you want to live. But if you take pride in what you common for women, before everything. are doing you’ll do a great job – and that’s all you can do.

Ein persönlicher Blick

Am ersten Dienstag im Oktober habe ich Es ist bezeichnend für Donna Strickland, tan. Chris Ferrie – ein Absolvent aus Water- nicht schlecht gestaunt, als am späten dass sie sich dem nicht angeschlossen hat. loo und heute etablierter Wissenschaftler in Vormittag feststand, dass meine frühere Als Laserphysikerin hätte sie sich auch mit der Quanteninformationstheorie – berich- Kollegin Donna Strickland den Nobelpreis den für die Quantentechnologie eher rele- tete von der großartigen Erfahrung, bei ihr erhalten wird. Das war unerwartet, weil sie vanten schwächeren Lasern beschäftigen die Bachelorarbeit zu machen. Die Geduld ein stiller Star ist. können. Aber sie wollte lieber ihrem Inte- seiner Betreuerin war auch dann noch nicht Nach dem Bachelor an der McMaster resse folgen als der Universitätspolitik. Sie erschöpft, als er einen sehr teuren Kristall Universität in Hamilton, Ontario, hat sie auf hatte immer eine überschaubare Gruppe, beschädigt hatte. Als Folge ihres hohen der amerikanischen Seite des Ontariosees mit der sie kontinuierlich, aber nicht immer Ansehens und dem Willen, der Communi- in Rochester promoviert. Danach arbeitete hochrangig publiziert hat. Im Mediensturm ty zu dienen, war Donna Strickland auch sie am National Research Council of Canada, nach dem Nobelpreis kam manchmal ihr Präsidentin der Optical Society of America. in Berkeley und Princeton. Sie ist 1997 wie- überschaubarer h-Index zur Sprache, der Daneben hat sie selbst die undankbarsten der in ihre Heimat zurückgekehrt: Waterloo ihr weniger wichtig war. Tätigkeiten im Department nicht gescheut. ist weniger als eine Autostunde von ihrem Mit Donna Strickland ging der Nobel- Bei Kaffee und Donut vor dem Kollo- Geburts- und ihrem Studienort entfernt. In preis an eine Wissenschaftlerin, welche quium sagte sie einmal zu mir: „If anyone der Zeit von 2006 bis 2011 haben wir im die Moden und die Optimierung der for- from our field will ever get a Nobel, it will gleichen Department zwar nicht wissen- malisierten Beurteilung von Wissenschaft be Ferenc Krausz.“ Sie hätte sich niemals schaftlich, aber administrativ zusammen- weitgehend vermieden hat. Sie macht gute selbst ins Gespräch gebracht. Ich kenne sie gearbeitet. Physik, getrieben durch ihr Interesse. Außer- eher als zurückhaltende Wissenschaftlerin Der Fachbereich Physik in Waterloo war dem ist sie bekannt als herausragende Do- in ihrer Community in Kanada. Kurz nach lange Zeit relativ klein und hatte unter an- zentin auf allen Ebenen. Ihre Vorlesungen der Ankündigung des Nobelpreises wurde derem kein Graduiertenprogramm. Donna zur nichtlinearen Optik finden großen in den Medien diskutiert, dass sie noch kein hat das Department vor und während sei- Anklang bei Studierenden aus allen Vertie- „full professor“ war. Solche Dinge haben sie nes Aufstiegs Anfang der 2000er-Jahre mit fungsrichtungen. Viele der Masterstudie- einfach nicht gekümmert – sie wollte nur getragen. Kurz danach begann ein großer renden und Promovierenden, selbst mit den gute Physik machen. Darin ist sie ausge- Aufschwung, gekennzeichnet durch die Schwerpunkten Stringtheorie oder Quan- zeichnet! Neben der hohen Signifikanz, dass Gründung eines privaten An-Institutes teninformation, haben ihre Vorlesungen mit sie erst die dritte Physiknobelpreisträgerin (Perimeter Institute for Theoretical Physics) Begeisterung belegt. Viele Studierende, die überhaupt ist, zeichnet dieser Preis auch die und interdisziplinären Initiativen in der sich nach dem ersten Studienjahr in der na- ungeplante, interessengetriebene, evaluati- Universität (Institute for Quantum Compu- turwissenschaftlichen Fakultät für die Phy- onsimmune Physik aus. ting) – beides finanziert durch große private sik entschieden haben, haben dies wegen Prof. Dr. Frank Wilhelm-Mauch, Spenden. einer Vorlesung von Donna Strickland ge- Universität des Saarlandes