2015 Paterson medal and prize

Dr Edmund Kelleher, Imperial College London, for his many contributions to pulse-width and wavelength-versatile fibre-based photonic sources.

Dr Edmund Kelleher

Edmund Kelleher is internationally recognised for his leading research in optical-fibre-based source technology that has impacted both the scientific and commercial communities. Kelleher has made important contributions in the development of versatile sources exhibiting extensive wavelength- and pulse-width selectivity, marked by their simplicity, broad application and commercial attractiveness. Of particular note are the two distinct themes he has proposed and developed: the pulse-width controlled giant-chirp fibre laser and the spectrally controlled continuous wave (CW) pumped super-continuum source, both very simple in concept and construction, both distinctly different sources, but both of considerable impact.

The giant-chirp pulse fibre laser is important in that it allows long pulses to develop in mode-locked fibre lasers with pulse duration controlled, from picoseconds to nanoseconds, by the overall normal dispersion of the fibre. These long pulses enable large amplification factors without nonlinear effects distorting performance, while the chirped nature of the pulse permits compression external to the laser and the achievement of enormous peak powers. Despite unsubstantiated initial doubts in the international community as to the quality of the pulses, Kelleher devised a unique technique, demonstrated both theoretically and experimentally the true chirped nature of the pulses, and has recently demonstrated compression by a factor of 100. Kelleher has also simplified high power super-continuum or “white light laser” sources, utilising CW pumping and achieving spectral coverage from the visible to near infra-red in compact configurations, highlighting the vital role of the pump laser linewidth. This and his current work, as a Royal Academy of Engineering research fellow, on the universal pulse source, a wavelength-tunable short pulse fibre laser dependent only on a readily available CW pump signal, is also at the vanguard of modern photonics technology.