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The development of a diamond Raman laser could open up a raft of newapplication areas in, for example, underwater imaging, medical imaging,ophthalmology, cancer therapy and multispectral imaging. The project will beled by Dr. Alan Kemp at the Institute of Photonics, University of Strathclydesupported by a grant of more than GBP600,000 from the UK government-fundedEngineering and Physical Sciences Research Council, EPSRC.
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The use of diamond as a solid-state laser material opens up newopportunities to design small, compact solid state lasers with greater powerhandling capabilities and operating at currently unavailable wavelengths soopening up new application areas. Diamond has a unique combination of opticaland thermal properties that make it suitable for this application and theseproperties can be exploited through the latest single crystal CVD materialproduced by Element Six. Raman lasers have already been developed usingmaterials such as silicon, for example, and are used in telecommunications,but the use of diamond could move their capabilities to new power levels andwavelengths.
How Raman lasers work
Raman lasers make use of a phenomenon called Raman Scattering discoveredin 1922. When photons hit a substance, a tiny fraction of them interact bycausing the atoms of the substance to vibrate. In such 'inelastic'collisions, the photons gain or lose specific amounts of energy, resulting inlight of a different wavelength. A Raman laser amplifies the secondary lightby oscillating it and pumping energy into the system to emit a coherent laserbeam.
The importance of this type of laser is that it can shift the wavelength.As Dr. Kemp says the ability to shift the wavelengths "gives access to theapplications-rich, but currently source-poor, yellow-orange region of thespectrum." Today, most commercial lasers operate in the near infrared regionof the spectrum between 0.8 microm to 1.1 microm with a particularconcentration around 1 microm (1.03 - 1.07 microm) where most of the highperformance laser work is done. "Perhaps the most important challenge inmodern solid-state laser engineering," says Dr. Kemp, "is to find ways togenerate new wavelengths but in doing so to retain as much as possible of theconvenience and performance of current lasers."
Potential of synthetic diamond
In addition, current generations of continuous wave solid state Ramanlasers have been limited to powers of only a few watts due to thermalproblems. Diamond has excellent thermal conductivity combined with a lowthermal 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 todeal with heat," points out Dr. Kemp. "This is particularly problematic inhigh power Raman lasers because crystals that are good Raman converters aretypically rather poor conductors of heat. This is where diamond comes in.With a thermal conductivity that is two to three orders of magnitude betterthan typical Raman active crystals, it should be an excellent Raman mediumand allow us to generate much higher output powers." In addition, diamondshifts the wavelength slightly further than the Raman-active crystals thatare currently used which may extend its application potential. "The team atthe Institute of Physics has recognised that diamond has a high Raman gaincoefficient and a large Raman shift compared to conventional Raman media,"adds Chris Wort, Technical Manager at Element Six.
A vital property of the diamond supplied by Element Six is that itexhibits ultra-low birefringence. Birefringence is when the speed of light ina medium varies if the polarisation of the light changes and this has to becarefully controlled in a laser cavity in order to make the laser work well.Dr. Kemp says, "The ultra-low birefringence single crystal CVD diamond thatE6 produces is a real step forward for all photonics applications of diamond,particularly laser applications. It allows us to exploit the exceptionalproperties of diamond without compromising other aspects of the laser'sperformance."
Element Six is to supply the research team with high quality singlecrystal CVD diamond for the duration of the project. The Institute ofPhotonics has a good working relationship with Element Six. The organisationshave previously worked together on the government supported MIDDI projectunder which has led to the ability to carry out precision etching of singlecrystal diamond micro-optics, for example.
About Element Six
Element Six is the world's leading supplier of high qualitysupermaterials used throughout manufacturing industry for a wide range ofapplications. It is the frontrunner in the development of synthetic diamondand novel engineering materials that are being used in industrialapplications that span, for example optical, mechanical, thermal, electronic,automotive, telecommunications and medical industries. With a turnover ofmore than US$500m and almost 4,000 employees, Element Six has establishedproduction and processing plants in China, Germany, Ireland, Sweden, SouthAfrica, Ukraine and the UK supported by a global distribution network.
About the Institute of Photonics
The Institute of Photonics, established in 1995, is acommercially-oriented research unit, part of the University of Strathclyde.Its key objective is to bridge the gap between academic research andindustrial applications and development in the area of photonics. TheInstitute's research interests include semiconductor materials and devices,practical, all solid state lasers, micro-LED arrays and a wide range ofapplications particularly in biophotonics. The Institute of Photonics isbased in Strathclyde's Glasgow city centre campus. The IoP undertakescontract and collaborative research with industry and offers consultancy. Ithas a large number of PhD and EngD students, and licences technologies tocompanies.For more information contact: John Caldwell Corporate Communications Element Six Tel: +353-(0)61460015 Email: [email protected] http://www.e6.com Institute of Photonics University of Strathclyde Wolfson Centre 106 Rottenrow Glasgow G4 0NW Tel: +44-141-548-4120 Fax: +44-141-552-1575 Email: [email protected] http://www.photonics.ac.uk
SOURCE Element Six Ltd
