3 kHz, 28.3 mJ, 65 ns, Q-switched Nd:YAG laser with Innoslab amplification

A laser diode (LD) end-pumped Nd:YAG laser system delivering clean acousto-optic Q-switched seed pulses and their efficient amplification using an Innoslab amplifier is reported. By inserting an intracavity mirror with a transmittance of 70%, Q-switched mode-locking (QML) in the long cavity acousto-optic Q-switched oscillator is effectively suppressed, enabling a stable and clean Q-switched pulse profile over the entire output range. At a pump power of 15.7 W, the seed laser delivers a single pulse energy of 0.68 mJ at a repetition rate of 3 kHz with a pulse width of 65 ns, corresponding to beam quality factors of M_x² = 1.09 and M_y² = 1.07. The output energy is further scaled using a double-pass Innoslab amplifier with a hybrid cavity configuration. At an absorbed pump power of 305.3 W and an injected seed energy of 0.3 mJ, a single pulse energy of 28.3 mJ is achieved. The corresponding beam quality factors M² are 1.23 and 1.09 in the horizontal and vertical directions, respectively, with an optical-to-optical conversion efficiency of 27.5% and a gain factor of 94.