Laser pulses produce glowing plasma filaments in open air, could enable long-distance monitoring.
Laser filamentation overcomes diffraction over a highly extended distance, making itself a powerful tool for long-range stand-off detection and light detection and ranging (LIDAR) applications. Mid-infrared (mid-IR) wavelengths are optimal for detecting biochemicals and air pollutants due to molecular fingerprints.
MIT Researchers have found a new way of using mid-infrared lasers to turn regions of molecules in the open air into glowing filaments of electrically charged gas, or plasma. The new method could make it possible to carry out remote environmental monitoring to detect a wide range of chemicals with high sensitivity.
The new system makes use of a mid-infrared ultra-fast pulsed laser system to generate the filaments, whose colors can reveal the chemical fingerprints of different molecules.
Comparing to the near-IR, the mid-infrared (mid-IR) wavelengths offer the greatest promise for detecting a wide variety of biochemical compounds and air pollutants. Researchers who have tried to generate mid-IR filaments in open air have had little success until now.
Only one previous research team has ever succeeded in generating mid-IR laser filaments in air, but it did so at a much slower rate of about 20 pulses per second. The new work — which uses 1,000 pulses per second — is the first to be carried out at the high rates needed for practical detection tools.
