Quantum dot optical superradiance, broadband amplifiers, lasers and laser cooling: QUDOS

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Amplification of light has lead to a revolution in many facets of human activities: from heavy industrial laser applications to bio-medical diagoneses. The fundamental principle of amplification is based on the energy conversion from a short wavelength to a longer wavelength, determined and usually associated with a dopant in the host material. We aim to lift some of the restrictions to open new spectral windows for gain by using engineered "atoms" in the form of quantum dots (QDs) to perform three functions: Amplification, lasing and the inverse of lasing: solid state cooling with lasers. Rather than finding a laser to match the absorption spectrum of the dopant, the principal advantage of the QD is that by modifying its size, it can exhibit absprption at virtually any wavelength, matching it to any laser wavelength. This has many advantages for creating new sources for lasing, openning new wavelength regions for amplification (for example in the 1200nm wavelength region, where high gain is principally only possible with Raman scattering), and ultimately for laser induced cooling, which has been a preserve of very few material systems, requiring extremely high purity and quality of samples. Our theory and modelling show that using the schemes of superradiance, as well as QDs, it is possible to open this process to a much larger set of glasses and crystals, by making them significantly more tolerant to non-radiative processes such as Auger recombination, and may be used with high phonon energy materials. The ultimate aim is to allow the use of the best glass system: Silica, as well as other commercially materials systems, such as chalcogenides and ZBLAN glass fibres.