Frequency resolved transverse mode instability in rod fiber amplifiers.

Frequency dynamics of transverse mode instabilities (TMIs) are investigated by testing three 285/100 rod fibers in a single-pass amplifier setup reaching up to ~200W of extracted output power without beam instabilities. The pump power is increased well above the TMI threshold to uncover output dynamics, and allowing a simple method for determining TMI threshold based on standard deviation. The TMI frequency component is seen to appear on top of system noise that may trigger the onset. A decay of TMI threshold with test number is identified, but the threshold is fully recovered between testing to the level of the pristine fiber by thermal annealing the fiber output end to 300°C for 2 h.

[1]  Michel Piché,et al.  Thermal effects in high-power CW fiber lasers , 2009, LASE.

[2]  J. Limpert,et al.  Thermo-optical properties of air-clad photonic crystal fiber lasers in high power operation. , 2003, Optics express.

[3]  David J. Richardson,et al.  High power fiber lasers: current status and future perspectives [Invited] , 2010 .

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

[5]  Liang Dong,et al.  Stimulated thermal Rayleigh scattering in optical fibers. , 2013, Optics express.

[6]  S. Unger,et al.  Non-isothermal bleaching of photodarkened Yb-doped fibers. , 2009, Optics express.

[7]  A. Galvanauskas,et al.  Chirally Coupled Core Fibers at 1550-nm and 1064-nm for Effectively Single-Mode Core Size Scaling , 2007, 2007 Conference on Lasers and Electro-Optics (CLEO).

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

[9]  B. Ward,et al.  Origin of thermal modal instabilities in large mode area fiber amplifiers. , 2012, Optics express.

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

[11]  Johannes Kirchhof,et al.  Temperature influence on the photodarkening kinetics in Yb-doped silica fibers , 2011 .

[12]  T. Alkeskjold,et al.  Estimating modal instability threshold for photonic crystal rod fiber amplifiers. , 2013, Optics express.

[13]  Marko Laurila,et al.  Distributed mode filtering rod fiber amplifier delivering 292W with improved mode stability. , 2012, Optics express.

[14]  Kristian Rymann Hansen,et al.  Theoretical analysis of mode instability in high-power fiber amplifiers. , 2013, Optics express.

[15]  Cesar Jauregui,et al.  Temporal dynamics of mode instabilities in high-power fiber lasers and amplifiers. , 2012, Optics express.

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

[17]  David C. Brown,et al.  Thermal, stress, and thermo-optic effects in high average power double-clad silica fiber lasers , 2001 .

[18]  Cesar Jauregui,et al.  High-speed modal decomposition of mode instabilities in high-power fiber lasers. , 2011, Optics letters.

[19]  J. Limpert,et al.  Thermo-optical properties of air-clad photonic crystal fiber lasers in high power operation. , 2003, Optics express.

[20]  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).

[21]  Kristian Rymann Hansen,et al.  Thermally induced mode coupling in rare-earth doped fiber amplifiers. , 2012, Optics letters.

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