SA digital laser a world first

February 14th, 2014, Published in Articles: Vector


by Hans van de Groenendaal, EE Publishers

South African researchers have developed the world’s first digital laser, creating many new applications for laser technology

Fig. 1: Images displayed on the LCD screen inside the laser to control the  shape of the laser.

Fig. 1: Images displayed on the LCD screen inside the laser to control the shape of the laser.

Conventional laser devices commonly consist of mirrors, energy (light) and a casing containing a medium, for example crystal or glass. The medium changes the frequency of the light to create a laser beam for a specific application.

Recently, researchers at South Africa’s Council for Scientific and Industrial Research (CSIR) have developed the world’s first digital laser.

This development opens up many new applications for laser technology. It also has the potential to reduce the cost of current applications. The work which led to the development of a digital laser system was done in the mathematical optics group at the CSIR National Laser Centre in Pretoria. The team, led by Dr. Andrew Forbes, chief scientist and research group leader, was supported by post-doctoral fellow Dr. Igor Litvin, and doctoral students Sandile Ngcobo and Liesl Burger. Ngcobo, who conducted the breakthrough experimental work as part of his PhD studies, believes the digital laser development demonstrates the CSIR’s ability to lead innovation in this field.

In conventional lasers, the shape of the light emitted is either not controlled at all, or a single shape is selected by expensive optics. For example, when a doctor undertakes surgery, the beam must be appropriate for precision-cutting. Alternatively, the laser light can be shaped after exiting the laser using a spatial light modulator – a liquid crystal display (LCD) which can be digitally addressed with grey-scale images representing the desired change to the light. The CSIR team has demonstrated for the first time that this can all be done inside the laser.

Fig. 2: Sandile Ngcobo in the  CSIR laser laboratory.

Fig. 2: Sandile Ngcobo in the
CSIR laser laboratory.

“Our digital laser uses the LCD as one of its mirrors fitted at one end of the laser cavity. Just as with LCD screens, the LCD inside the laser can be sent pictures to display. When the pictures change on the LCD the properties of the laser beams that exit the device change accordingly,” explains Forbes.

“The researchers showed that by sending an appropriate picture to the LCD, any desired laser beam could be created inside the laser device. The team programmed the LCD to play a video of a selection of images representing a variety of desired laser modes. The result was that the laser output changed in real-time from one mode shape to another. This is a significant advancement from the traditional approach to laser beam control, which requires costly optics and realignment of the laser device for every beam change. Since this is all done with pictures, the digital laser represents a paradigm shift for laser resonators,” says Forbes. “The dynamic control of laser modes could open up many future applications, from communications to medicine. The CSIR device represents a new way of thinking about laser technology. We see it as a new platform on which future technologies may be built.”

Ngcobo says he believes the digital laser will be a “disruptive” technology. “This is technology which may change the status quo and which could create new markets and value networks within the next few years or decade”.

“The research into the digital laser continues. It adds to the CSIR’s strong track record in the development of laser technology in mathematical optics.”

As with other CISR developments, the digital laser breakthrough offers opportunities for industry to develop new applications. Whereas in the past laser cutting was controlled by a robotic arm, the digital laser can be programmed to perform the entire cutting function.

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