An invention resonates with a local laser manufacturer

A breakthrough by CSIR chief scientist, Prof Andrew Forbes, led to the design and development of a new laser system with special optics inside, characterised by features on the micro-scale. The technology was licensed to a South African company in 2011.

“Quite something to see one’s idea and design go all the way to inclusion in a commercial product,” says Forbes. “Not all research and development results in uptake, and because the time lapse from the initial work to uptake by industry or society is often significant, inventors are not always present to experience this thrill. I feel privileged to have experienced this.”

He says that the work that led to this technology started as early-stage research on laser resonators. Lasers are made up of three parts, namely an energy source, a gain medium, and mirrors that form an optical ‘box’ resonator.

“The technology worked well, with obvious commercial benefit, which led to us opting to license it to an industry player,” he remarks.

Forbes explains what happened at the lab on the day of the breakthrough, “The beam jumped the single mode energy, up by a factor of 25. It turned a commercially nonviable process into a viable process for a local laser exporter. It surprised me how well it worked and that it did so, on the very first attempt.”

“With lasers, one generally has to choose between having lots of energy, and having a ‘nice’ laser beam. A quality that incorporates both these parameters is the so-called ‘brightness’ of a laser: high brightness means good laser beam quality and high energy. This is difficult to achieve because good beams tend to come at the expense of energy, while high-energy beams are highly distorted and difficult to use in practical applications,” Forbes explains.

The new CSIR laser technology  makes almost any laser operate in a ‘high brightness’ mode, which results in more efficient lasers for long-range  communication systems,and in the military for target designation. The technology has the potential to make lasers smaller and less expensive, by exploiting the extra efficiency to make the support systems work a little less.

The CSIR has for several years invested in developing core expertise in shaping light with diffractive optical elements; optics that have feature sizes down to the micrometre  scale, and sometimes to the nanometre scale.

The idea is that given a laser beam of a particular intensity profile (i.e. how the energy carried by the laser is distributed in space), it is possible to reshape the profile of this laser beam by redistributing the energy.

If this is done correctly, then in principle any laser beam shape can be achieved. The group worked on achieving this same result, but inside a laser, so that the diffractive optical elements are the mirrors of the laser.  The idea was that if the mirrors were correctly calculated, and then fabricated, the laser itself would select the best beam for maximum brightness. The shape of the laser beam bouncing around inside the laser was chosen to extract as much energy as possible from the laser, but in a ‘good’ shape.

The licence agreement sees CSIR technology helping to make local industry more competitive. In this case, the aim was a more efficient industrial laser, but similar technology can be used to make almost any laser operate in a ‘high brightness’ mode.