Efficient pulsed Nd-doped fiber laser at 905 nm and frequency conversion to 452nm and 226nm

We present in this work, the development of a nanosecond pulsed Master-Oscillator Power-Amplifier (MOPA) laser system near 905 nm based on the 3-level transition of Neodymium using a novel low NA polarization-maintaining Nd-doped silica fiber with a 30µm core and 130µm cladding. The MOPA delivered up to 24 W of average power (0.6 mJ energy per pulse) with good beam quality (M²~1.4). Cascaded LBO and BBO crystals are used respectively for second-harmonic generation and fourth-harmonic generation, giving respectively average output powers of 4.9W at 452nm (conversion efficiency of 20%) and 550mW at 226nm (conversion efficiency of 10%).