Direct amplification of a nanosecond laser diode in a high gain diode-pumped Nd:YVO₄ amplifier.

We demonstrate that Nd:YVO₄ can efficiently amplify a nanosecond laser diode in a very simple double-pass configuration. Based on longitudinal pumping with a high brightness fiber-coupled laser diode at 808 nm (60 W, 100 μm, 0.22 NA) and a low Nd-doped (0.2%) temperature controlled Nd:YVO₄ we achieved an optical gain of 62 dB with very low (<2%) parasitic laser emission and an average output power of 10 W. At 15 kHz, we observed a strong gain saturation dynamic resulting in a pulse duration reduction from 100 to 3.5 ns. This effect enhances the peak power by a factor of 18 (130 kW) with an energy of 620 μJ.