| The theory calculation of diode-pumped Nd:YAG multi-pass laser amplifier has been performed to get much profound knowledge to the Thctors a~cting t~a1 efficiency of the amplifier in this thesis. On the basis of the knowledge, the experiments on small signal gain measurement and power amplification of diode-pumped Nd:YAG two-pass power amplifier have been carried out, obtaining the data such as small signal gain, output energy, energy storage efficiency, exIrction efficiency and so on. Some factors have been analyzed affecting energy storage efficiency and extraction efficiency of the amplifier. The multi-pass amplification model, fit for amplification system of diode-pumped solid-state laser (DPL), has been founded with combination of theory calculation and experiment. The main results can be summarized as follows: I. The physics model of zigzag-slab multi-pass laser amplifier has been founded. The numerical simulation program. applied to calculation of small signal gain distribution of the slab side- pumped and of multi-pass amplification of the beam in the amplifier, has been made with Windows interface by means of the numerical calculation method of dividing up the slab and thinning down the input beam. 2. The energy storage process of diode-pumped Nd:YAG slab laser amplifier has been numerically simulated, calculating the small signal gain distribution of the slab side-pumped. obtaining the measurement method of small signal gain of the amplifier. In our experiment, the small signal gain factor of O.238cm?and energy storage efficiency of about 25% have been measured at diode pump energy of 21 8.75mJ.The experiment data have been compared with the numerical calculation results, showing a good consistency. 3. The factors such as input flux, small signal gain, gain recovery factor, beam fill factor and loss and so forth , affecting extraction efficiency of zigzag-slab multi-pass laser amplifier, have been emphatically analyzed. After the experiment study and comparison among three master oscillator two-pass power amplifier configuration, the conclusion has been obtained that extractlon.efflciency of amplifier can be improved by means of increasing input energy and beam flh1foroa condition that beam quality of output laser of master oscillator is well. The single pulse energy of 51 .9mJ and extraction efficiency of 51.8% have been measured in the experiment on diode-pumped Nd:YAG slab two-pass power amplifier. Inserting the experiment data into multi-pass amplification model formula, we obtained the calculation results nearly consistent with the experiment data. |
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