Controlling the waveform of ultrashort infrared pulses – News Physics and Quantum Computing

An international team of laser physicists from the attoworld team at LMU and the Max Planck Institute for Quantum Optics has achieved unprecedented control over light pulses in the mid-infrared wavelength range.

Ultrashort infrared light pulses hold the key to a wide range of technology applications. The oscillating infrared light field can excite molecules in a sample to vibrate at specific frequencies or drive ultrafast electrical currents in semiconductors. Anyone wishing to exploit the oscillating waveform of ultrashort light pulses, for example to drive advanced electro-optical processes, faces the same question: how best to control the waveform itself. Generation of ultrashort pulses with tunable waveforms has been demonstrated in different wavelength ranges like UV-visible and near-infrared. Physicists from the attoworld team at LMU, the Max Planck Institute for Quantum Optics (MPQ) and the Hungarian Molecular Fingerprinting Center (CMF) have now successfully generated ultrashort mid-infrared pulses and controlled accurately their electric field waveforms. With this handy infrared waveform manipulator, new possibilities of optical control for biomedical applications and quantum electronics are at your fingertips.

The basis of the new mid-infrared source is a stabilized laser system that generates light pulses with a precisely defined waveform at near-infrared wavelengths. The pulses consist of a single oscillation of the light wave and therefore only last a few femtoseconds. When these pulses are sent into a suitable nonlinear crystal, the generation of long-wavelength infrared pulses can be induced by taking advantage of complex frequency mixing processes. In this way, the team succeeded in producing light pulses with an exceptionally wide spectral coverage of more than three optical octaves, from 1 to 12 micrometers. The researchers were not only able to understand and simulate the underlying physics of mixing processes, but also developed a new approach to precisely control the oscillations of the generated mid-infrared light. Going through adjustment of the laser input parameters.

The resulting tunable waveforms can, for example, selectively trigger certain electronic processes in solids, which could enable much higher electronic signal processing speeds in the future. “On this basis, one could consider the development of electronics controlled by light”, explains Philipp Steinleitner, one of the three main authors of the study. “If opto-electronic devices were to operate at the frequencies of generated light, you could speed up today’s electronics by at least a factor of 1000.”

Attoworld physicists pay particular attention to the use of new light technology for the spectroscopy of molecules. When mid-infrared light passes through a sample liquid, such as human blood, the sample molecules begin to oscillate and in turn emit characteristic light waves. Molecular response detection provides a unique fingerprint that depends on the exact composition of the sample. “Thanks to our laser technology, we have considerably extended the range of controllable wavelengths in the infrared,” explains Nathalie Nagl, also the first author of the study. “The additional wavelengths allow us to analyze the composition of a mixture of molecules even more precisely,” she continues.

Within the attoworld group, colleagues from the Broadband Infrared Diagnostics (BIRD) team led by Mihaela Zigman and the CMF Research team led by Alexander Weigel are particularly interested in the precise measurement of infrared molecular fingerprints of blood samples. human. The vision is to identify characteristic signatures that help diagnose diseases like cancer. A developing tumor, for example, causes small, very complex changes in the molecular composition of the blood. The objective is to detect these changes, and to allow the early diagnosis of diseases by measuring the infrared fingerprint of a single drop of human blood.

“In the future, our laser technology will allow our colleagues to detect previously undetectable changes in specific biomolecules such as proteins or lipids. It thus increases the reliability of future medical diagnoses using infrared laser technology,” says Maciej Kowalczyk, also the first author of the study.

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Materials provided by Ludwig-Maximilians-Universität München. Note: Content may be edited for style and length.

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Controlling the waveform of ultrashort infrared pulses – News Physics and Quantum Computing

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