LONDON -- Researchers at the Institute of Photonics, University of Strathclyde, have started work on a three and a half-year project to develop a solid-state laser design incorporating CVD (chemical vapour deposition) diamond manufactured by Element Six Ltd.
The project will be led by the Institute's Dr. Alan Kemp, and is supported by a grant of more than £600,000 from the UK government-funded Engineering and Physical Sciences Research Council, EPSRC.
The researchers say the use of diamond as a solid-state laser material opens up new opportunities to design small, compact solid state lasers with greater power handling capabilities and operating at currently unavailable wavelengths so opening up new application areas.
This should have applications in numrous areas, for example, underwater imaging, medical imaging, ophthalmology, cancer therapy and multispectral imaging.
They add diamond has a special combination of optical and thermal properties that make it suitable for this application and these properties can be exploited through the latest single crystal CVD material produced by Element Six.
Raman lasers have already been developed using materials such as silicon, for example, and are used in telecommunications, but the use of diamond could move their capabilities to new power levels and wavelengths. The importance of this type of laser is that it can shift the wavelength.
According to Dr Kemp, the ability to shift the wavelengths "gives access to the applications-rich, but currently source-poor, yellow-orange region of the spectrum."
Perhaps the most important challenge in modern solid-state laser engineering,"adds Kemp, "is to find ways to generate new wavelengths but in doing so to retain as much as possible of the convenience and performance of current lasers."
Current generations of continuous wave solid state Raman lasers have been limited to powers of only a few watts due to thermal problems. Diamond has excellent thermal conductivity combined with a low thermal coefficient of expansion allowing greater power handling capability.
"The least glamorous but most pervasive problem in laser engineering, particularly when you want high performance in a small package, is how to deal with heat," stresses Dr. Kemp. "This is particularly problematic in high power Raman lasers because crystals that are good Raman converters are typically rather poor conductors of heat.
However, with a thermal conductivity that is two to three orders of magnitude better than typical Raman active crystals, diamond should be an excellent Raman medium that will allow the researchers to generate much higher output power
A vital property of the diamond supplied by Element Six is that it exhibits ultra-low birefringence. Birefringence is when the speed of light in a medium varies if the polarization of the light changes and this has to be carefully controlled in a laser cavity in order to make the laser work well.
"The ultra-low birefringence single crystal CVD diamond that E6 produces is a real step forward for all photonics applications of diamond, particularly laser applications. It allows us to exploit the exceptional properties of diamond without compromising other aspects of the laser's performance," says Kemp.
The Institute of Photonics and Element Six have already worked together on UK Government supported MIDDI project which has led to the ability to carry out precision etching of single crystal diamond micro-optics.
Element Six Ltd. (E6) was formerly DeBeers Industrial Diamonds Ltd.
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