Boffins double infrared laser efficiency

US scientists have published details of a technique that doubles the efficiency of infrared lasers.

Researchers at the Center for Quantum Devices at Northwestern University said that new turbo-charged lasers could be used in next-generation defence systems to fool incoming missile attacks or detect explosives or toxins in the atmosphere.

Such devices could also be used in commercial applications like trace chemical analysis, pollution monitoring and free space communication.

The mid-infrared wavelength range (three to five microns) is especially useful for defence-based applications.

Laser technology in this range has been targeted by the US Defense Advanced Research Projects Agency as a 'strategic technology'.

The agency, which is sponsoring the research, created the Efficient Mid-wave Infrared Lasers (EMIL) programme to develop high efficiency, compact semiconductor laser sources with the hope of demonstrating high power and high power efficiency (50 per cent) from an individual laser at room temperature.

When the EMIL programme started in March 2007, state-of-the-art mid-infrared semiconductor lasers, developed at Northwestern University, boasted power efficiencies on the order of five to 10 per cent at room temperature.

Over the past year, researchers at the Center for Quantum Devices have gradually improved this figure through changes to material quality, design and fabrication.

Currently a record power efficiency of 22 per cent has been realised at room temperature.