CSIR breakthrough in laser technology

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IBG - SA Instrumentation & Control Buyers' Guide

February 2010 News

CSIR scientists have made a breakthrough in the design of laser resonators resulting in a technology that is set to revolutionise the laser industry. Chief scientist Dr Andrew Forbes of the CSIR National Laser Centre says, “We can now design lasers with an exceptional beam and with a much higher energy output. This is an amazing discovery. If someone had asked me a year ago if it was possible to select a Gaussian beam with a micro-mirror concept, I would have said no.”

He explains that the resonator is the core component of any laser and that laser beams originate within the resonator. “The shape and size of the resonator therefore determines the size and strength of the laser beams. Usually lasers will give out many beams of various shapes and sizes, each carrying some of the energy. The smallest beam that can be generated in a standard laser is the Gaussian beam.”

According to Forbes, Gaussian laser beams are in great demand for many applications due to their low rate of divergence as they propagate and their smooth intensity profile. They also facilitate communication with satellites, as the beams do not disperse when travelling through space.

“Unfortunately, the Gaussian beam occupies a small volume inside the laser, so the energy extracted from it is always low. For a long time it has been thought that only by ‘throwing away’ some of the energy of the medium, thereby restricting the size of laser beams that could survive, could the smallest beam – the Gaussian beam – be created,” says Forbes.

Forbes and Igor Litvin, a PhD student at the CSIR, have shown that it is possible to overcome this limitation by not following the standard approach to designing laser resonators but by metamorphosising the desired beam at the output of the laser, to a beam with better energy extraction qualities inside the resonator.

The metamorphosis also allows the Gaussian beam to be selected by using micro-optical elements, something that was previously thought impossible. This discovery will enable the design of lasers that output Gaussian beams with significantly higher energy – a phenomenon that has proved elusive to laser scientists over the past 50 years.

For more information contact Lehlohonolo Mokhema, CSIR, +27 (0)12 841 3716, [email protected], www.csir.co.za

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