1, The result shows that the self-pulsing solutions are always unstable either for the thrid of laser systems or for the fourth class of laser systems.

2, The mode competition and self-pulsing effect were regarded as the main factors that affect the output stability performance of the laser.

3, Based on the self-pulsing theory in fiber laser and the spatial-coupling model in solid state laser, the physical mechanism of pulsed laser generation is investigated and explained.

4, The self-pulsing current has unchangeable rising time under various conditions. The experimental results indicate that the self-pulsing is a behavior controlled by the discharge process.

5, Theoretical calculation for prediction of optical unstability by SPW has been obtained and some experiments were carried out, optical unstability of self-pulsing, bifurcation and chaos were observed.