Austrian-German research team demonstrates for the first time an attosecond "oscilloscope" rendering the hyper-fast field oscillations of visible light
Fig. 1: Energy shift (in units of eV) suffered by an attosecond electron probe set free at different instants (measured in units of fs) in an intense wave consisting of only a few cycles of red light. Image: Max Planck Institute for Quantum Optics / Technical University Vienna
Fig. 2: Build-up and disappearance of the electric field in the 4.3-fs pulse of red light (wavelength ~ 750nm), as recorded by the attosecond oscilloscope. Image: Max Planck Institute for Quantum Optics / Technical University Vienna
The human eye can detect changes in the intensity of light, not however the wavelength because light oscillates too fast (approximately 1000 trillion times per second). An international collaboration led by Ferenc Krausz and made up of researchers from the Vienna University of Technology, the Max-Planck-Institute for Quantum Optics and the University of Bielefeld have recently succeeded in developing a technique which can measure the instantaneous electric field of red light (quarter period ~ 620 attoseconds) and record its variation with a resolution of 100 attoseconds (Science, August 27, 2004). The experiment of the Austrian-German team allowed the first direct visualization of the electric field of visible light and constitutes the fastest measurement to date.
It has been known since the famous experiments of Heinrich Hertz near the end of the 19th century that light is a wave consisting of electric and magnetic fields, just as radio waves and microwaves. The only difference is in the number of times these fields change their direction in a second. In radio and microwaves this happens typically millions to trillions times per second. The field variation in these waves can be readily detected by turning it into electric current and displaying the variation of this current in electronic instruments called oscilloscopes.
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