Compact ultra-high gain multi-pass Nd:YAG amplifier with a low passive reflection phase conjugate mirror

We show a compact multi-pass amplifier, based on a single dual-rod laser-head which produces ultra-high gain. A double-pass produced a maximum small signal gain of 4×10 8. Another double-pass was permitted by including a specially designed Brillouin phase conjugate mirror (PCM). This enabled a total gain of 7.7×10 10, which raised an input signal of 10 pJ to 770 mJ output signal. To the best of our knowledge this is the highest gain reported to date from any type of laser amplifier scheme. The amplification system is fairly simple in that it consists of only one dual-rod laser head and hence only a single power supply. We show that this system can be utilized for producing high-energy long temporally-smooth narrow linewidth pulses, as well as high power controllable, temporally-modulated pulses.