6.2 W 589 nm yellow laser by extra-cavity sum-frequency

A 6.2 W 589 nm yellow laser at a repetition rate of 800 Hz was reported. Double rod and symmetry plane-plane cavity was adopted. The gain medium was Nd:YAG, 11.1 W 1 064 nm and 12.6 W 1 319 nm was obtained by acousto-optic (AO) Q-switched. The sum-frequency medium was a 4 mm×4 mm×30 mm lithium triborate (LBO) crystal with type Ⅰ critical phase match. Two beams were combinated with beam splitter and focused into the LBO crystal. A maximum power 6.2 W of the 589 nm laser was obtained, laser pulse width was 50 ns. The sum-frequency efficiency was 26.2%. The beam quality factor was 3.20 and 3.61 respectively in parallel and perpendicular direction．