Visiting Fellowship for Professor E.P. Ippen

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This grant application is made for funds to partially support the Visiting Fellowship of Professor Erich Ippen from MIT to the Femtosecond Optics Group at Imperial College London in order to undertake a collaborative research programme on femtosecond pulse generation and dynamics in fibre lasers and passive fibre devices. Professor Ippen is one of the world's leading experts on the generation, characterization and application of ultrashort pulses.One of the newest fibre lasers has Bismuth as the active ion for laser action and compared to other rare earth doped silica based fibres it is unique in the broad extent of its fluorescence or gain profile. Consequently, the broad spectral profile, which could make it attractive for telecomunications applications is also capable of supporting ultrashort pulses. Professor Ippen is the world's leading expert on passive mode locking techniquies, where the introduction of various elements ( saturable absorbers) that exhbit an intensity dependent transmission into the laser cavity, lead to the evolution and self synchronization of ultrashort pulses from the apparently random output of the free running laser. Originally the saturable absorbers were organic dyes, however, currently solid state devices such as semiconductors or single walled carbon nanotubes suspended in cellulose films are currently being investigated. Both of these wioll be used to investigate femtosecond pulse generation in bismuth doped silica fibre and also thullium doped silica fibre. The latter will also be employed in conjunction with cascaded high power fibre amplifiers to generate high average and high peak power poulses that will be used to generate an ultrabroad continuum of wavelengths in fluoride based fibre that will cover the mid infra red from 2 to 5 microns.The basic formation mechanism of the supercontinuum in optical fibre will also be investigated and the role of noise both on the dynamics and on the long wavelength enhancement of the supercontinuum will be examined.