<title>30W Yb<formula><sup><roman>3+</roman></sup></formula> pulsed fiber laser with wavelength tuning and its second harmonic generation</title>

Abstract

We have investigated various operation regimes and resonator designs of the diode-pumped Yb3+-doped fiber laser, containing acoustooptic filter and modulator inside the resonator. To imbed the polarization sensitive acoustooptic tunable spectral filter into the polarization non-maintaining resonator, based on an isotropic single-mode fiber, without 3db polarization losses, CaCO3 single-crystal non-dispersive polarization splitter was applied. By utilizing special designed laser resonator with acoustooptic filter and modulator inside, there were obtained stable smooth bell-shaped pulses, their duration depending on the resonator traveling time and their repetition rate being determined exclusively by the outer generator, controlling the acoustooptic modulator. More than 20nm acoustooptic tuning band of pulsed Yb3-doped fiber laser radiation and 100nm tuning of CW one were obtained without polarization losses. 30W stable average power was reached through the two-stage amplification, using Yb3+-doped fiber and 14μm MFD W-fiber. For the sake of improving the laser cutting resolution we have investigated the possibility ofthe effective Second Harmonic Generation ofthis pulsed Yb3+-doped fiber laser radiation. 4W stable output average Second Harmonic power was obtained through the Second Harmonic Generation along the X-axis of the KTP crystal, further increasing of Second Harmonic power being limited by the thermal self-focusing of the Second Harmonic radiation, resulted in crystal damage.© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.