[NEWS] A new mid-infrared light source for high-sensitivity molecular detection
Abstract: Physicists from the University of Munich (LMU) in Germany and the Laboratory for Attosecond Physics (LAP) of the Max Planck Institute for Quantum Optics (MPQ) have recently developed a new mid-infrared ultrafast light source with high power and ultra-wide spectral range. The successful development of this light source has opened up a new way for new application research in many fields such as medical care, life sciences, and material analysis.
Using mid-infrared light source can detect molecules with high sensitivity. With the help of mid-infrared light, researchers can search for the particles that shape and determine human life. The key to this is that mid-infrared light has the property of causing molecules to vibrate. Scientists are making extensive use of this property to analyze the molecular composition of samples. In order to make this analysis more accurate, Dr. Jinwei Zhang and Dr. Ka Fai Mak of the Attosecond Physics Laboratory of the University of Munich and the Max Planck Institute for Quantum Optics in Germany and their group colleagues recently developed a new mid-infrared light source with an ultra-wide spectrum. This light source can be used to help detect very small numbers of molecules in liquids such as blood, and is a world leader in related fields.
When mid-infrared light encounters molecules, they vibrate. In this process, each specific type of molecule is excited by a specific wavelength of light. The vibrational lines of most molecules lie in the range of 3-20 microns. By examining the spectrum of light emitted by molecules after this excitation, researchers can infer the molecular composition of samples such as blood and breath gases. The wider the spectrum and the higher the power of the mid-infrared light source, the higher the accuracy of the detection and inference results.
Physicists at LAP decided to face this challenge. They developed the world's first femtosecond mode-locked thin-disk laser operating at a 2-micron wavelength, capable of emitting 77,000,000 laser pulses per second with an average power of 19 watts. The time scale width of a pulse is around 300 femtoseconds (1 femtosecond = 10-15 seconds). Based on this thin-sheet laser, they used a nonlinear transformation method to generate a spectrum covering the range of 4.5-20 microns (the visible range is from 0.35-0.7 microns). It covers almost all the vibrational spectral line wavelength ranges of molecules. This is the broadest mid-infrared spectrum obtained so far based on a solid-state laser in the world. If this spectrum is transformed into the time domain, a pulse width of the order of periods can be obtained. This new mid-infrared light source also opens the door for scientists to better understand the fundamental properties of solid and soft matter. By analyzing the spectrum after the interaction between light and matter, combined with mid-infrared spectroscopy and microscopy techniques, the research results can be made more accurate.
Scientists from the LAP team applied this new mid-infrared light source in a project called "Broadband Infrared Detection." Within this framework, they became interested in exploring the molecular composition of blood and respiratory gases. This will bring great convenience to medical fields such as early cancer detection. If specific molecules that appear only in cancer patients are detected in a person's blood and breath gas, this can be used as a reliable basis for early diagnosis of cancer. Further inspection will be necessary next. This new tool for early disease detection is also already under development. Mid-infrared light sources enable highly sensitive detection of molecules. With the help of mid-infrared light, researchers can search for the particles that shape and determine human life. The key to this is that mid-infrared light has the property of causing molecules to vibrate. Scientists are making extensive use of this property to analyze the molecular composition of samples.
The laser system developed by LMU and MPQ scientists is the world's first mid-infrared laser source capable of covering the 4.5-20 micron spectral range (two octaves)
Original document:
[1] Jinwei Zhang, Ka Fai Mak, Nathalie Nagl, Marcus Seidel, Dominik Bauer, Dirk Sutter, Vladimir Pervak, Ferenc Krausz, and Oleg Pronin Multi-mW, few-cycle mid-infrared continuum spanning from 500 to 2250 cm-1 Light: Science and Applications (2018) 7, 17180; doi:10.1038/lsa.2017.180
Original English text link:
http://www.munich-photonics.de/public-outreach/news/n/a-keen-sense-for-molecules/