Gunter Steinmeyer, Max Born Institute, Germany, Subcommittee Chair, S&I 8
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This year’s CLEO Conference, sponsored by APS/Division of Laser Science, IEEE Photonics Society and the Optical Society includes S&I 8: Ultrafast Optics, Optoelectronics and Applications which is part of the Science & Innovations technical program. Tom Giallorenzi, OSA’s Science Advisor interviewed Gunter Steinmeyer, Subcommittee Chair, S&I 8: Ultrafast Optics, Optoelectronics and Applications, to find out about some of the trends for this year’s hot paper submissions.
Tom Giallorenzi: Can you highlight an invited paper or two?
Gunter Steinmeyer: Among the invited papers, there is one paper that reflects general trends – that we also see in the submitted papers and there is now a lot of papers about optical parametric schemes for generating short pulses, in particular in the mid-infrared for generating extremely broadband radiation that can be compressed – back into a short pulse.
Tom Giallorenzi: What is the interest in doing it in mid-infrared?
Gunter Steinmeyer: In the mid-infrared, there’s a high interest because if you drive attosecond pulse generation schemes – you are hoping to get a much higher cutoff, and much higher energies. So the hope that is connected to these sources is basically x-ray generation at shorter wavelengths than can be – achieved with high harmonic generation schemes nowadays.
Tom Giallorenzi: We have one of the inventors of the attosecond science giving a plenary talk. Could you say a little bit about him?
Gunter Steinmeyer: Paul Corkum will be giving a plenary talk on attosecond pulse generation. He’s one of the pioneers in the field, and particularly on the theoretical side. He explained high harmonic generation. I think he’s one of the first scientists and also the inventor of many different schemes that have now been employed and tested for attosecond pulse generation.
Tom Giallorenzi: We’ve heard a lot about attosecond pulses. What would you say is the – forefront in the research these days in attosecond?
Gunter Steinmeyer: The forefront in terms of pulse duration, I think the shortest I ever heard of it sub-70 attosecond pulse and – I think these are very sophisticated schemes that also address the dispersion of these very challenging wavelengths.
Tom Giallorenzi: Why would it be interesting to attend the sessions?
Gunter Steinmeyer: This year in my topical area, there are some, I think, new emerging trends or strengthening trends that we’ve already seen in the last years. One of them is definitely optical parametric pulse generation schemes and there’s a lot of contributed papers. There’s also an invited paper on this topic.
hese papers focus on the generation of few-cycle pulse shapes in the mid-infrared, which is an important driver wavelength for attosecond pulses. Then, there are a lot of contributed papers concerning the control of the carrier-envelope phase. This has actually surprised me that there’s now still so many papers, and this is really exploding a little bit. And then there are also very interesting papers concerning the generation of coherent supercontinua which can be compressed back into very, very short pulses covering only like one or two cycles in the envelope.
Tom Giallorenzi: Can you say a little more about that, what’s the importance of carrier-envelope phase stabilization?
Gunter Steinmeyer: Carrier-envelope phase stabilization is one of the key technologies for making attosecond pulses. Without having a carrier-envelope phase stabilized driver pulse train, you basically only end up with random attosecond generation, only every, I don’t know, - tenth pulse or so is actually really a short and useful attosecond pulse.
Tom Giallorenzi: And this allows you to make them stable and hit every pulse?
Gunter Steinmeyer: It allows you to generate stable attosecond pulse trains – that can actually really be used in an easy way in an experiment. Otherwise, you could only use every tenth and always have to measure the carrier-envelope phase on the side and then later sort out of which of the events were useful and which are not, and the shorter the pluses get, probably, the less efficient your scheme will get if you don’t have this carrier-envelope phase stabilization.
Tom Giallorenzi: If you had to summarize what are the frontiers in nonlinear optics?
Gunter Steinmeyer: Yes. So, one of the invited papers in S&I 8 is an invited talk about the higher order – Kerr effect, and this is one effect that has caused a lot of discussion in the recent years, and I think this is one of the discussions that is moving at the limits of our current – understanding of nonlinear optics.
Tom Giallorenzi: Why is the Kerr effect important?
Gunter Steinmeyer: The Kerr effect is important, for example, to understand filamentation. Optical filamentation has recently always been discussed that it can only be caused by plasma generation. Now there are indications that filamentation could be possible, maybe not at 800 nanometers, maybe at longer wavelengths due to this higher-order stabilizing Kerr effect, and such a filament, if exists at all would then be dissipation-less. So you wouldn’t have to generate the electrons which will, I mean, eventually bleed out all the energy of your pulse.
Tom Giallorenzi: So this would potentially allow you to propagate in a filament for a very long reach?
Gunter Steinmeyer: Yes. That would be one of the implications.
Tom Giallorenzi: Are there other implications?
Gunter Steinmeyer: There is, of course, a strong connection also to higher-order harmonic generation – and then again to the attosecond pulse generation schemes.
Tom Giallorenzi: Could you repeat that by saying some of the – it’s a – if you can, repeat the question.
Gunter Steinmeyer: Another implication or another connection of the higher order Kerr effect is to high-high harmonic generation. Basically, this is the refraction twin of these generation schemes and consequently, there’s also a link to attosecond generation schemes. Therefore, I think this effect is highly interesting.
For more information on the Science & Innovations program, visit www.cleoconference.org for more information. For more exclusive insider info on trends in ultrafast optics, view the video interview.