Distributed mode filtering rod fiber amplifier delivering 292W with improved mode stability.

We demonstrate a high power fiber (85 μm core) amplifier delivering up to 292 Watts of average output power using a mode-locked 30 ps source at 1032 nm. Utilizing a single mode distributed mode filter bandgap rod fiber, we demonstrate 44% power improvement before the threshold-like onset of mode instabilities by operating the rod fiber in a leaky waveguide regime. We investigate the guiding dynamics of the rod fiber and report a distinct bandgap blue-shifting as function of increased signal power level. Furthermore, we theoretically analyze the guiding dynamics of the DMF rod fiber and explain the bandgap blue-shifting with thermally induced refractive index change of the refractive index profile.

[1]  Kristian Rymann Hansen,et al.  Thermo-optical effects in high-power ytterbium-doped fiber amplifiers. , 2011, Optics express.

[2]  Arlee V. Smith,et al.  Mode instability in high power fiber amplifiers. , 2011, Optics express.

[3]  Cesar Jauregui,et al.  High average power large-pitch fiber amplifier with robust single-mode operation. , 2011, Optics letters.

[4]  Marko Laurila,et al.  Single-Mode ytterbium-doped Large-Mode-Area photonic bandgap rod fiber amplifier. , 2011, Optics express.

[5]  T. Eidam,et al.  The impact of modal interference on the beam quality of high-power fiber amplifiers. , 2011, Optics express.

[6]  F. Salin,et al.  Photodarkening and Photobleaching of an Ytterbium-doped Silica Double-clad LMA fiber , 2007, 2007 Conference on Lasers and Electro-Optics (CLEO).

[7]  Cesar Jauregui,et al.  The influence of index-depressions in core-pumped Yb-doped large pitch fibers. , 2010, Optics express.

[8]  J. Rothhardt,et al.  Extended single-mode photonic crystal fiber lasers. , 2006, Optics express.

[9]  Marko Laurila,et al.  Q-switching and efficient harmonic generation from a single-mode LMA photonic bandgap rod fiber laser. , 2011, Optics express.

[10]  T. Eidam,et al.  Experimental observations of the threshold-like onset of mode instabilities in high power fiber amplifiers. , 2011, Optics express.

[11]  Christopher D. Brooks,et al.  Multimegawatt peak-power, single-transverse-mode operation of a 100μm core diameter, Yb-doped rodlike photonic crystal fiber amplifier , 2006 .