The generation of short, tunable high power optical pulses

Ure, Kenneth Alexander Norman (1988) The generation of short, tunable high power optical pulses. University of Southampton, Doctoral Thesis.

Abstract

In the first part of this thesis we present work on active modelocking and Q-switching of pulsed solid-state lasers. A transient analysis of the process is presented taking into account dispersion of cavity elements and the effect of intra cavity bandwidth limiting etalons. The performance of a Nd:YAG and ruby laser is compared with the predictions of this theory.

For many applications, tunability is required and we go on to describe a pulsed synchronously pumped dye laser. A simple rate equation model is presented which has been used to predict the output characteristics of the dye laser and how these depend on pump pulse energy, duration and cavity mismatch between dye laser and pump laser. The design of a longitudinally pumped and a transversely pumped dye laser is described and their performance fully characterised.

Since the pulse energy obtainable from both the actively modelocked and the synchronously pumped oscillators is modest, we examine the amplification of short optical pulses. Mechanisms which may reduce the gain when the seed pulse duration becomes less than the re-thermalisation time constant of upper laser levels or the relaxation time of the lower laser levels are considered. Experimental observations in Nd:YAG, Ruby and dye amplifiers are presented.

Finally, the usefulness of these short pulse lasers has been extended by shifting their wavelengths using non-linear optical techniques. Conversion efficiencies obtained are compared to theoretical predictions. (DX84796)

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