A new type of laser developed by the University of Adelaide will lead to major advances in the remote sensing of greenhouse gases, thanks to its ability to operate over a large range within the infrared light spectrum.
While most lasers work only at one wavelength of light, the research team from the University of Adelaide and Macquarie University engineered their laser so it can be tuned to different wavelengths. Furthermore, the laser can be tuned over a very large wavelength range.
The researchers say the laser has the largest wavelength tuning ever demonstrated by a fibre laser, with its range reaching further into the mid-infrared than ever achieved before from a fibre laser operating at room temperature.
The flexibility and wavelength range of this laser will be useful for detecting gases, says project leader Associate Professor David Ottaway from the University of Adelaide's School of Physical Sciences and the Institute for Photonics and Advanced Sensing.
This is because the laser operates in a wavelength range in which the "molecular fingerprints" of many organic molecules occur, where the gases absorb patterns of light at different frequencies.
“The new laser is operating at a wavelength where many hydrocarbon gases, including the greenhouse gases, absorb light,” Associate Professor Ottaway explained.
“This means that by changing the wavelength of our laser, we can measure the light absorption patterns of different chemicals with a high degree of sensitivity."
The laser will allow researchers to detect small concentrations of gases at considerable distances. The ability to remotely detect greenhouse gases such as methane and ethane means in the future it will be possible to quickly and reliably distinguish between various emission sources, and pinpoint problematic areas, such as the leaking of gases.
The laser could also form the basis of devices that can analyse trace gases in exhaled breath, in order to detect the presence of diseases. For example, diabetes patients' breath contains detectable traces of acetone.
This has major implications for gas detection, because the main limitation to date with laser detection of gases has been the lack of suitable and affordable light sources that can produce enough energy and operate at the correct part of the light spectrum.
With this multi-wavelength, tuneable laser, it is now possible to replace multiple instruments for detecting individual gases, with one, reducing costs.
Additional improvements include the use of an optical fibre which is easier to work with, being less bulky and more portable, and also cheaper to produce than other types of laser.