March 2016
Spotlight Summary by Brynmor Davis
Ptychographic reconstruction of attosecond pulses
The fastest pulses of light can be painfully slow to measure, but a new technique promises to make it easier. Over the last decade it has become increasingly common to generate and measure optical pulses lasting only tens to hundreds of attoseconds. These phenomena are extremely brief - an attosecond is a billionth of a billionth of a second, and in 50 attoseconds light travels only about the width of a white blood cell. Measuring attosecond pulses is complicated by the fact that we have no shorter-duration yardstick to compare them against; instead it is necessary to mix pulses together, take measurements of the combined field using comparatively slow detectors, and then make indirect inferences based on the collected data. This sort of inference is common in science - for example, recently discovered exoplanets are too small to observe directly; but were inferred from a slight dimming of starlight, seen as the planet transited our line of sight to the star it orbits. However, to make a successful inference it is necessary to collect sufficient data, and in many cases this means a lot of data. Current attosecond-pulse measurement techniques often involve taking measurements of many different mixes of optical pulses. What the authors describe in this paper is a new data processing method which requires substantially fewer measurements, while producing results of similar quality. The paper introduces the method (which is based on "ptychography" tools used in other fields), shows analysis and computer simulations, and then presents experimental results to validate their approach. The method described has the potential to simplify attosecond optical metrology and so open up new possibilities for ultrafast experimental design.
Note: the authors have provided their related code at http://figshare.com/articles/attosecond_Extended_Ptychographyc_Iterative_Engine_ePIE_/1601876
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Note: the authors have provided their related code at http://figshare.com/articles/attosecond_Extended_Ptychographyc_Iterative_Engine_ePIE_/1601876
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Article Information
Ptychographic reconstruction of attosecond pulses
M. Lucchini, M.H. Brügmann, A. Ludwig, L. Gallmann, U. Keller, and T. Feurer
Opt. Express 23(23) 29502-29513 (2015) View: Abstract | HTML | PDF