Chalcogenide Photonic Technologies

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Chalcogenides are materials based on metallic alloys of sulphur, selenium and/or tellurium. Although only formed into glasses for the first time in the 1950's, they emerged first in a new generation of CD's and DVD's where their ability to be formed into glass and crystalline structures allow information to be stored. This optical storage is based on changes of optical properties when a laser heats the chalcogenide material and converts it from crystalline to glass structure. This phase change effect is also being actively investigated for electronic memories ultimately aiming to replace present memory stick technology. Chalcogenides here offer vastly higher read and write rates, smaller memory cell size and improved stability over time.In the proposed work, we are aiming to develop further optoelectronic applications of chalcogenides by exploiting and enhancing our expertise in depositing thin films of chalcogenide and subsequently forming light guides in these films. The confinement of light in the guides will enhance the guided light power and could lead to devices based on phase change as above. However the chalcogenides have much faster and stronger responses to light, which can be engineered to be extremely effective through the waveguide structure allowing us to develop ultra-high speed optical switch elements, devices for converting between light wavelengths (changing the 'colour') and quantum light sources emitting photons in 'spookily connected' entangled pairs . By doping our waveguides with transition metals we expect to make lasers at a significant number of new wavelengths, particularly in the infrared region. Chalcogenide glass has higher transmission at much longer wavelengths than conventional glasses extending the laser applications to eyesafe rangefinders for aerospace, chemical sensing and specialist medical sensors.