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Diamonds are a laser's best friend

Into focus Australian researchers have developed a unique method of improving the quality of high-powered laser beams using Marilyn Monroe's favourite gemstone.

A girl's best friend they might be, but diamonds also have special properties when it comes to dispersing heat. They have good optical scattering qualities too, effectively reshaping light beams.

According to the lead researcher, Dr Aaron McKay of the Photonics Research Centre at Macquarie University in Sydney, these properties make diamonds much better at producing high quality laser beams than conventional techniques, especially for high power lasers.

"Diamonds have a massive potential to make lasers travel much further and improve the beam quality, or more importantly the beam brightness, which allows you to focus the power of the laser beam onto a small target," he says.

To change a poor quality laser beam into a high-quality one you need to use a laser converter. But in conventional systems this always leads to a loss of power and the production of a lot of unwanted heat.

Using diamond, the team found that after conversion the quality, or brightness, of the output beam was 50 per cent higher than the input beam.

"Our work has demonstrated a diamond-based converter for enabling beam brightness enhancement for the first time," says McKay.

Better thermal properties

Conventional conversion techniques are electronically and optically complicated, while the heat produced causes more problems than it solves, including affecting the quality of the laser beam.

"Diamond is such an awesome material in terms of its thermal properties. It is very efficient and has up to 1000 times better heat handling capability than other materials," says McKay.

Because the technique uses a diamond measuring just millimetres in length it also means conversion can take place using a much smaller device, increasing portability.

The beam conversion occurs using a process known as Raman scattering, which not only improves the quality of the beam, but also converts its colour or wavelength. The researchers used this property to convert the beam wavelength into the less dangerous 'eye-safe region'.

Lasers in this part of the spectrum are in great demand for applications including range finding, remote sensing and point-to-point communication, which is often used between navy ships.

Scaling up

The team plans to take the research a lot further, including adapting the concept to combine many poor-quality lasers into a single stronger beam.

"We are also looking at scaling the power up from the 15 to 20 watt level to watt levels in the hundreds. Currently the processes that don't use diamonds are limited to about 10 watts. We want to show a massive improvement in that," McKay says.

The latest research results have just been published in Laser & Photonics Reviews .