This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Researchers at the University of Oldenburg's Institute of Physics are working on techniques for precision control of electric fields of light, which allow the dynamics of individual electrons to be manipulated in experiments. Now a team from the Attosecond Microscopy research group, led by Dr.
Jan Vogelsang, has taken a decisive step toward this goal. In a paper published in the journal Applied Physics B—Lasers and Optics, the researchers present a laser system that generates 200,000 light pulses per second. Six Oldenburg researchers collaborated with members of a research group led by physics Nobel laureate Anne L'Huillier at Lund University in Sweden to perform a detailed characterization of the laser system.
During the experiments, the precise position of the light wave—consisting of infrared light, which is invisible to the human eye—remained extremely stable even over periods of several hours. The stable light fields resulting from a continuous series of identical light pulses make experiments on electron control possible—foundational research that could eventually lead to the development of devices such as ultrafast transistors that operate at the speed of light. The new aspect of this work, as Katrin Meier, lead author of the study, explains, is the potentially record-breaking similarity among all 200,000 laser pulses per second.
The researchers were able to control the stability of the electric field oscillations across a wide range of timescales, from microseconds to hours. The key factor is the "carrier-envelope phase" (CEP), which, together with other parameters, defines the exact shape of the light wave: "You can think of the pulse as a brief flash during which there is room for only a few peaks and troughs in the oscillation of the electromagnetic field. The CEP determines where these peaks and troughs are located within the flash," says Meier, a doctoral candidate in the research group.
"Without a stable CEP, one pulse or flash would be completely different from the next—and controlled experiments that use the fields within the pulse would be impossible." Because the CEP is extremely sensitive to temperature fluctuations, air movements and even the slightest vibrations, a meticulously planned and executed laser setup, together with the exceptionally stable conditions in the Oldenburg attosecond lab, is essential to its stability. Nevertheless, the stability of the CEP in the current experimental setup took the team by surprise, Meier says. Although the CEP describes only a very small quantity, it can have a major influence on measurement results, she explains: "A minimal shift in the CEP can determine how electrons react to the laser pulse—much like a precisely timed 'push' determines the direction in which a swing swings." The excellent stability of the CEP in the now-established setup opens up the possibility of conducting experiments in which it has previously been impossible to record any measurement signals whatsoever.
Katrin Meier et al, Multiscale carrier-envelope phase characterization of 2-µm pulses delivered by a 200-kHz optical parametric amplifier, Applied Physics B (2026). DOI: 10.1007/s00340-026-08699-w Provided by Carl von Ossietzky Universität Oldenburg BA art history, MA material culture. Former museum editor, paramedic, and transplant coordinator.
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