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New system for generating ultra-fast flashes of light discovered
New system for generating ultra-fast flashes of light discovered
An international research team consisting of the Institute of Photonics and Nanotechnology of the CNR (CNR-IFN), the Politecnico di Milano, the DESY in Hamburg and the Massachusetts Institute of Technology has managed to synthesise “optical waveforms” by means of the synchronised overlap of different light pulses. These light pulses, which can be “sculpted” according to the user’s wishes, will be used to study atomic and molecular processes. The results have been published in Nature Photonics
Since its invention in 1960, the laser has revolutionised not only the fields of science and technology, but also our everyday lives, with applications ranging from medicine to materials processing, fibre-optic communications to the preservation of our cultural heritage. One of the laser’s many exceptional properties is that it allows the user to generate incredibly short flashes of light, up to a duration of just a few femtoseconds, i.e. a few millionths of a billionth of a second. These pulses, thanks to their extremely short duration, allow us to study ultra-fast phenomena, such as the processes underlying vision and photosynthesis, and can, thanks to their extremely high intensity, modify atoms and molecules in order to create new states of matter. As such, controlling the properties and the temporal profile of these pulses is of utmost scientific and technological importance, and has been the object of intense study since the 1980s.
An international team of scientists involving the Politecnico di Milano, the Institute of Photonics and Nanotechnology of the CNR (CNR-IFN), the DESY in Hamburg and the Massachusetts Institute of Technology has managed to synthesise genuine ‘optical waveforms’ by controlling the electrical field of the light with an extremely high degree of precision, much less than a femtosecond. The results have been published in the journal Nature Photonics. The synthesis of these waveforms is based on an innovative optical process pioneered by the researchers from the CNR and the Politecnico: coherent synthesis, i.e. the synchronised overlap of different light pulses.
“It’s like directing an orchestra. Each pulse is a musical instrument, called upon to produce its own sound; coherent synthesis is the perfect execution of a piece of music. This orchestra could potentially produce an infinite multitude of waveforms - that is, melodies. As such, the coherent synthesis achieved in these experiments is a very promising approach for the generation of laser light pulses of any shape and duration,” explains Cristian Manzoni, researcher at the CNR-IFN and the Politecnico.
Many years of work went into the experiment. “We built the first prototype - which was the start of everything - right in the laboratories of the Politecnico di Milano,” adds Giulio Cerullo from the Department of Physics at the Politecnico di Milano. “It was like a little ensemble, but from that first experiment, published in 2012, came the idea to put together the large orchestra we have now. The experimental apparatus was reconstructed and expanded at the laboratories in Hamburg”.
The waveforms that can now be synthesised will increase the opportunities to control the way light interacts with matter, especially at high intensities. In this case, the electromagnetic field of the light is so strong that it can counteract the forces that bind electrons to nuclei; the light can temporarily remove electrons from the atom and cause them to orbit along brand new trajectories. For example, it has been demonstrated that when the electron moves propelled by such short and intense waveforms, it generates even shorter light pulses lasting just a few attoseconds, in other words billionths of a billionth of a second. These are the shortest artificial events that man has ever been capable of creating. This research is laying the foundations for the study of new atomic and molecular mechanisms, in that it will allow us to examine nature through light pulses that are “sculpted” according to the user’s wish.
Factsheet
Who: Institute of Photonics and Nanotechnology of the CNR (CNR-IFN), the Politecnico di Milano, the DESY in Hamburg and the Massachusetts Institute of Technology
What: “Sub-cycle mJ-level Parametric Waveform Synthesizer for Attosecond Science”, an article published in Nature Photonics; DOI: 10.1038 / s41566-020-0659-0.
https://www.nature.com/articles/s41566-020-0659-0, https://rdcu.be/b5Awh
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