Green Q-switched microsecond laser pulses by overcoupled intracavity second harmonic generation

In order to achieve laser pulses with microsecond duration in the green spectral range, we investigated the effect of overcoupled intracavity second harmonic generation with a Q-switched transversally diode pumped Nd:YLF laser. KTP and LBO crystals with different lengths were used to study the laser pulse energy, shape and duration at 526.5 nm. A pulse energy of 4.3 mJ was achieved with a FWHM pulse duration of 650 ns using a 5 mm long KTP and 3.4 mJ with 3.2 μs using a 10 mm long crystal. With a 10 mm long LBO a FWHM duration of 600 ns and with a 20 mm LBO 1.5 μs were generated both with a pulse energy of 4 mJ.