Mid-IR erbium-doped ZBLAN fiber laser is widely tunable
The emitter has the largest tuning range of any fiber laser.
A mid-IR rare-earth-doped fiber laser made of ZBLAN (zirconium fluoride/barium fluoride/lanthanum fluoride/aluminum fluoride/sodium fluoride) has an emission center wavelength of 3.5 μm and a tuning range of 450 nm; the long-wavelength end of its range, 3.78 μm, makes this laser the longest-wavelength emission from any room-temperature fiber laser.1 Developed at the University of Adelaide (Australia), has an output power of 1.45 W at its center wavelength.
Importantly, the laser operates in a wavelength range in which the spectroscopic "molecular fingerprints" of many organic molecules occur.
"In fact this laser has the largest wavelength tuning ever demonstrated by a fiber laser," says researcher Ori Henderson-Sapir.
"The new laser is operating at a wavelength where many hydrocarbon gases, including the greenhouse gases, absorb light," says David Ottaway, another researcher. "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. This will allow us to detect small concentrations of these gases at considerable distances. Remote detection of greenhouse gasses such as methane and ethane opens up the prospect of differentiating between various potential emission sources, such as natural gas extraction and agriculture, and so pinpoint areas of concern."
Other potential applications for the future include the possibility of analyzing trace gases in exhaled breath at a clinic to detect the presence of disease. For example, acetone can be detected in the breath when someone has diabetes.
The research was supported by the South Australian government through the Premiers Research and Industry Fund and the Australian Research Council.
1. Ori Henderson-Sapir et al., Optics Letters (2016); doi: 10.1364/OL.41.001676