CSIR (Council for Scientific and Industrial Research) laser scientists have made a breakthrough in the design of laser resonators – resulting in a technology that is set to revolutionise the laser industry.

The discovery has led to a submission to the Innovation Fund to prototype and commercialise the technology.
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 that is going to revolutionise the industry. 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 are created (or originate) within the laser 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 spreading 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 laser beam occupies a small volume inside the laser, so the energy extracted from the laser in this beam 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 beam 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 end 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 now enable us to design lasers that output Gaussian beams but with significantly higher energy – a laser phenomenon that has proved elusive to many laser scientists over the past 50 years.”
The work of Forbes and Litvin has been published in two acclaimed journals for optics and lasers, Optics Letters and Optics Express and has been patented.