| Laser Shock is a new surface treatment technology. Comparing with traditional surface treatment technique, Laser Shock has many obvious technical advantages such as non-contact, no heat affected zone and a significant strengthening effect, can greatly enhance the durability of metallic materials and prevent surface cracks, thereby enhancing the service life and lower maintenance repair costs. Shock processing laser is formed by an oscillator and one or more amplifiers.The research focuses on pre-amplifier which between the oscillator and main amplifier, and stimulated Brillouin scattering (SBS) phase conjugation mirror of main amplifier.The magnitude of the single frequency laser will be amplified from mJ to 100mJ by the pre-amplifier. Using Nd:YLF as work material of pre-amplifier in order to match the gain peak of Nd:glass used in main amplifier. The energy flow of multi-pass amplification has been simulated, the optical path of four-pass amplifier,the characters of Nd:YLF crystal and Polarization components have been analyzed. The synchronization of single frequency seed laser and electrical pump pulses. In the double-pass amplification experiment, the output energy is 40mJ, with a gain of 20. There is also some preliminary work of four-pass amplification.The SBS phase conjugate mirror applied in the main amplifier needs to achieve high reflectivity and fidelity in a high energy load conditions. Dual-cell structure and high breakdown threshold scattering medium FC-72 liquid are selected. SBS process was simulated numerically based on a one-dimensional transient model. Use an implicit finite differencing in time and a down-winding or backward differencing scheme in space. Under different parameters in amplified cell, theoretical simulate the impact of output energy and Waveform. Providing reference for structural design and experiment of dual-cell SBS phase conjugation mirror in laser system with lager energy and shot pulse. |
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