High-energy, sub-nanosecond linearly polarized passively Q-switched MOPA laser system

This study introduces a linearly polarized laser with a 0.6 J output energy and a 420 ps pulse width. Accordingly, [1 1 1]-cut Nd:YAG and [1 1 0]-cut Cr4+:YAG crystals are used to fabricate a linearly polarized seed laser. One side of both crystals is configured with a Brewster angle to enhance the extinction ratio of polarization. The output energy and the pulse duration of the seed laser are 2.51 mJ and 552 ps, respectively. The seed laser pulse is compressed to 420 ps using a fused-silica block, while its energy is amplified to 600 mJ. The output energy instability over a 90 min operation is ±4.7%.