Diamond makes laser beams more brilliant

Researchers have for the first time demonstrated that diamond can radically improve the quality of high power laser beams.
The findings, by Australia's Macquarie University, were made possible by exploiting optical interactions inside a diamond crystal of length several millimetres long.
"Lasers come in all sorts of colours and with beam powers that range from the milliwatt level we are familiar with in laser pointers and in DVD players, up to many thousands of watts, enough to burn through steel in a fraction of second," said lead researcher Dr Aaron McKay.
However, there is one fundamental property of a laser beam that is critical to applications - its quality, or, in the terminology of physicists, its coherence.

High quality lasers are needed to meet growing technological demands in applications as diverse as in materials processing, environmental and remote sensing, and in defence.
Beam quality and brightness are fundamental attributes that inherently make lasers so valuable.

"Standard methods used to increase beam brightness involve converting the beam in a second laser - a 'laser converter' - which inevitably leads to an overall loss of power," McKay said.
"This may be acceptable at low powers but not at the higher powers in which the large heat dissipated in the converter spoils the process," McKay added.
The device used by McKay and colleagues was highly efficient so that the brightness of the output beam was 50 per cent higher than the input beam.

The major advantage of using diamond is its outstanding ability to dissipate heat - faster than other optical materials and for conversion to be achieved passively in a very small package.
"Diamond is a very exciting laser material. Its properties in so many aspects are so much better than other materials that there are likely to be massive opportunities for greatly improving laser capability," said McKay.
The research was published in the journal Laser & Photonics Reviews.