High energy, high brightness picosecond master oscillator power amplifier with output power 65.5 W

In this article, it is demonstrated the generation of high pulse energy, high beam quality and high brightness mode-locked picosecond pulses from a compact Nd:YVO₄ master oscillator power amplifier system. This system mainly consisted of a SESAM mode-locked picosecond seed generator and four-stage multi-pass amplifiers. A pulse picker was adopted prior to power amplifiers to efficiently reduce the pulse repetition rate. The maximum average output power of 65.5 W was obtained with a repetition rate of 496.85 kHz and a pulse duration of 16.9 ps, corresponding to a maximum pulse energy of 131.83 µJ and a peak power of 7.8 MW. While simultaneously, the output beam quality factors along the x axis and the y axis were measured to be M_x ²=1.36 and M_y ²=1.32, respectively, therefore, a brightness as high as 3.22 × 10⁹ W·cm^-2·Sr was achieved. As far as we all know, this is the highest brightness for a picosecond pulsed Nd:YVO₄ MOPA laser at 1064 nm.