| In some laser applications, it's often required a high-energy (or power) laser. To obtain high-energy laser, there are many difficulties by the laser itself only. This is because raising the output power of laser and other parameter (such as monochrome, pulse width, modulated performance, beam divergence angle et al.) are contradictory. Use of Q-switch or mode-locking technology, can get extremely high peak power. The high peak power of the laser is due to the energy compressed in a very short time. But such high peak power laser by the fact the output energy often does not great. Therefore, in order to get excellent performance of high-energy laser, master-oscillator power amplifier (MOPA) to become an ideal choice. The thesis details the research of the Yb3+ doped double-clad fiber laser used in master-oscillator power amplifier (MOPA) system which pumped by Laser Diodes. The main theoretical and experimental researches are included in this thesis:(1) The state of the researches and the development way in the field of fiber laser worldwide are summarized. The characteristic and advantage of MOPA technology is introduced, and the practical significance of this research subject is also introduced.(2) The characteristic of double-clad fiber is analyzed, and the principle how the pulse fiber amplifier worked in the master-oscillator power amplifier system is expounded.(3) Theoretical numerical analysis of the transient-state of the Yb3+ doped double-clad fiber amplifier which is pumped by 976nm LD, amplify the 1064nm seed laser and get the high-power output has been preformed. The reverse population density distribution under certain pump power, the effect of fiber length, pump power and input light pulse energy on output power and the single pulse waveform distortion after amplification have been analyzed.(4) Based on the theory analysis above, the result can be benefit for the design of experiment system. Analyze the result of the experiment and find the shortcoming of the theory model. |
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