Low-threshold mode instability in few-mode Yb3+-doped fiber amplifiers: an overview of recent results

We present an overview of theoretical analysis and experimental observation of the spatio-temporal transverse mode instability in polarization-maintaining high-gain fiber amplifiers with a high concentration of Yb3+ ions and core diameters of 8-10 μm. The nonlinear power transformation of the LP01 fundamental mode into the high-order modes is explained by a traveling refractive index grating accompanying a population grating induced by the mode interference field. The origin of the refractive index gratings is discussed. The threshold power for the transverse mode instability is found to depend on the fiber core diameter, numerical aperture, dopant concentration and the signal bandwidth. The threshold power is observed to decrease dramatically in the presence of a backward reflection of a signal from the output fiber facet.

[1]  H. J. Shaw,et al.  Resonantly Enhanced Nonlinearity in Doped Fibers for Low-Power All-Optical Switching: A Review , 1997 .

[2]  Michalis N. Zervas,et al.  Power scaling limits in high power fiber amplifiers due to transverse mode instability, thermal lensing, and fiber mechanical reliability , 2018, LASE.

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

[4]  Cesar Jauregui,et al.  Observation of transverse-mode instabilities in a thulium-doped fiber amplifier , 2019, LASE.

[5]  M. Zervas.  Transverse-modal-instability gain in high power fiber amplifiers: Effect of the perturbation relative phase , 2019, APL Photonics.

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

[7]  Arlee V. Smith,et al.  Increasing mode instability thresholds of fiber amplifiers by gain saturation. , 2013, Optics express.

[8]  O Antipov,et al.  Formation of dynamic cavity in a self-starting high-average-power Nd:YAG laser oscillator. , 1999, Optics express.

[9]  Tino Eidam,et al.  Femtosecond fiber CPA system emitting 830 W average output power. , 2010, Optics letters.

[10]  Arlee V. Smith,et al.  Mode instability thresholds of fiber amplifiers , 2013, Photonics West - Lasers and Applications in Science and Engineering.

[11]  Oleg Antipov,et al.  Low-threshold mode instability in Yb3+-doped few-mode fiber amplifiers: influence of a backward reflection , 2016, LASE.

[12]  Cesar Jauregui,et al.  Experimental investigation of transverse mode instabilities in a double-pass Yb-doped rod-type fiber amplifier , 2017, LASE.

[13]  K. Panajotov,et al.  Rate Equation for the Nonlinear Phase Shift in Yb-Doped Optical Fibers Under Resonant Diode-Laser Pumping , 2009 .

[14]  Cesar Jauregui,et al.  Physical origin of mode instabilities in high-power fiber laser systems. , 2012, Optics express.

[15]  Yong-Ho Cha,et al.  Transverse mode instability induced by stimulated Brillouin scattering in a pulsed single-frequency large-core fiber amplifier. , 2015, Applied optics.

[16]  Iyad Dajani,et al.  Theoretical and numerical treatment of modal instability in high-power core and cladding-pumped Raman fiber amplifiers. , 2016, Optics express.

[17]  K. Hejaz,et al.  Controlling mode instability in a 500 W ytterbium-doped fiber laser , 2014 .

[18]  D. J. Hagan,et al.  Kramers-Krönig relations in nonlinear optics , 1992 .

[19]  John W. Arkwright,et al.  Experimental and theoretical analysis of the resonant nonlinearity in ytterbium-doped fiber , 1998 .

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

[21]  S. Babin,et al.  Open-cavity fiber laser with distributed feedback based on externally or self-induced dynamic gratings. , 2017, Optics letters.

[22]  Oleg Antipov,et al.  Low-threshold mode instability in Yb3+-doped few-mode fiber amplifiers. , 2014, Optics express.

[23]  Jesper Lægsgaard,et al.  Static thermo-optic instability in double-pass fiber amplifiers. , 2016, Optics express.

[24]  Patrice Mégret,et al.  Resonantly Induced Refractive Index Changes in Yb-doped Fibers: the Origin, Properties and Application for all-fiber Coherent Beam Combining , 2010 .

[25]  Patrice Mégret,et al.  Effective recording of dynamic phase gratings in Yb-doped fibers with saturable absorption at 1064nm. , 2007, Optics express.

[26]  Simo Tammela,et al.  Photodarkening in ytterbium-doped silica fibers , 2005, SPIE Security + Defence.

[27]  R. Kronig.  On the Theory of Dispersion of X-Rays , 1926 .

[28]  M. Zervas,et al.  High Power Fiber Lasers: A Review , 2014, IEEE Journal of Selected Topics in Quantum Electronics.

[29]  Sudhir Trivedi,et al.  Pump-induced nonlinear refractive-index change in erbium- and ytterbium-doped fibers: theory and experiment. , 2005, Optics letters.

[30]  Andreas Tünnermann,et al.  Build up and decay of mode instability in a high power fiber amplifier. , 2012, Optics express.

[31]  Pengfei Ma,et al.  1.3 kW monolithic linearly polarized single-mode master oscillator power amplifier and strategies for mitigating mode instabilities , 2015 .

[32]  R. Stolen,et al.  Stimulated Brillouin scattering in optical fibers , 1972 .

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

[34]  W. Clarkson.  High power fibre lasers , 2002 .

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

[36]  Pu Zhou,et al.  Experimental studies of mode instability and thermal induced effects in all-fiber amplifier , 2013 .

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

[38]  M. Engholm,et al.  Experimental evidence for the formation of divalent ytterbium in the photodarkening process of Yb-doped fiber lasers. , 2013, Optics express.

[39]  Paul Michael Petersen,et al.  A general theory of two-wave mixing in nonlinear media , 2009 .

[40]  Marko Laurila,et al.  Frequency resolved transverse mode instability in rod fiber amplifiers. , 2013, Optics express.

[41]  M. Durkin,et al.  Modal instabilities in high power fiber laser oscillators. , 2019, Optics express.

[42]  V. Lucarini.  Kramers-Kronig relations in optical materials research , 2005 .

[43]  O. Antipov,et al.  Transverse-Mode Instability in High-Gain Few-Mode Yb3+-Doped Fiber Amplifiers With a 10-μm Core Diameter With or Without Backward Reflection , 2018, IEEE Journal of Selected Topics in Quantum Electronics.

[44]  Oleg L. Antipov,et al.  Pulse repetitive Nd:YAG laser with distributed feedback by self-induced population grating , 1998 .

[45]  Jian-jun Wang,et al.  Experimental study of the influence of mode excitation on mode instability in high power fiber amplifier , 2019, Scientific Reports.

[46]  Eric Honea,et al.  Threshold power and fiber degradation induced modal instabilities in high-power fiber amplifiers based on large mode area fibers , 2014, Photonics West - Lasers and Applications in Science and Engineering.

[47]  Jörg Neumann,et al.  Beam quality degradation of a single-frequency Yb-doped photonic crystal fiber amplifier with low mode instability threshold power. , 2012, Optics letters.

[48]  Oleg L. Antipov,et al.  Resonant two-wave mixing of optical beams by refractive-index and gain gratings in inverted Nd:YAG , 1998 .

[49]  Patrice Mégret,et al.  Refractive Index Changes in Rare Earth‐Doped Optical Fibers and Their Applications in All‐Fiber Coherent Beam Combining , 2013 .

[50]  M. Zervas,et al.  Transverse mode instability, thermal lensing and power scaling in Yb3+-doped high-power fiber amplifiers. , 2019, Optics express.

[51]  A. Fotiadi,et al.  Dynamics of pump-induced refractive index changes in single-mode Yb-doped optical fibers. , 2008, Optics express.

[52]  S. Unger,et al.  Photodarkening in Yb doped fibers: experimental evidence of equilibrium states depending on the pump power. , 2007, Optics express.

[53]  J. Limpert,et al.  Impact of photodarkening on the mode instability threshold. , 2015, Optics express.

[54]  Kristian Rymann Hansen,et al.  Impact of gain saturation on the mode instability threshold in high-power fiber amplifiers. , 2014, Optics express.

[55]  Pu Zhou,et al.  Mitigating transverse mode instability in all-fiber laser oscillator and scaling power up to 2.5 kW employing bidirectional-pump scheme. , 2016, Optics express.

[56]  Oleg Antipov,et al.  Influence of a backward reflection on low-threshold mode instability in Yb3+-doped few-mode fiber amplifiers. , 2016, Optics express.

[57]  A. Fotiadi,et al.  Electronic and thermal refractive index changes in ytterbium-doped fiber amplifiers. , 2013, Optics express.

[58]  Michalis N. Zervas,et al.  Power scalability in high power fibre amplifiers , 2017, 2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC).