Alongside carbon dioxide, methane is a key driver of worldwide warming. To detect and monitor the climate pollutants within the atmosphere precisely, scientists on the Max Planck Institute for the Science of Light (MPL) have developed a sophisticated laser technology. A high-power ytterbium thin-disk laser drives an optical parametric oscillator (OPO) to generate high-power, stable pulses within the short-wave infrared (SWIR) spectral range. This enables researchers to detect and analyze a wide range of atmospheric compounds. This novel method can play a vital role in tracking greenhouse gas cycles and the results of climate change and was recently published within the journal APL Photonics.
Short-lived pollutants play a critical role in global warming. For instance, methane is of particular relevance to the worldwide greenhouse effect because its warming potential is 25 times higher than that of carbon dioxide. Nonetheless, detecting and monitoring these pollutants is difficult for 2 reasons. Firstly, water vapor interferes and overlaps with the absorption spectra of many gases in the usual infrared ranges normally used for detection. Secondly, these pollutants are difficult to detect as a consequence of their volatile presence within the atmosphere. By targeting the SWIR range, where pollutants akin to methane absorb strongly while water absorption stays minimal, the brand new laser system offers unprecedented detection sensitivity and accuracy.
Central to this innovation is the ytterbium thin-disk laser, which produces high-power, femtosecond pulses at megahertz repetition rates. This enables the system to pump an OPO, converting laser pulses to the SWIR range with remarkable power and intensity. Operating at twice the repetition rate of the pump laser, the OPO delivers stable, tunable SWIR pulses optimized for high-sensitivity spectroscopic applications. The team’s pioneering approach also integrates broadband, high-frequency modulation of the OPO output, which allows the enhancement of the signal-to-noise ratio, providing even greater detection precision.
“The output of our laser system might be scaled to higher average and peak power, as a consequence of the facility scalability of ytterbium thin-disk lasers. Employing the system for the accurate detection of pollutants in real time allows deeper insights into greenhouse gas dynamics. This might help address a few of the challenges we face in understanding climate change.” said Anni Li, PhD student on the MPL.
The laser’s capability to generate high-power, stable pulses within the SWIR range is a game-changer for field-resolved spectroscopy and femtosecond fieldoscopy, methods which enable re-searchers to detect and analyze a wide selection of atmospheric compounds with minimal interference.
“This recent technology is just not only applicable to atmospheric monitoring and gas sensing, but in addition holds potential for other scientific fields akin to earth-orbit communication, where high bandwidth modulated lasers are required.” said Dr. Hanieh Fattahi, the lead researcher on the project. The researchers plan to develop the system further with the goal of making a flexible platform for real-time pollutant monitoring and earth-space optical communications.
