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Optics Express

Optics Express

  • Editor: C. Martijn de Sterke
  • Vol. 20, Iss. 10 — May. 7, 2012
  • pp: 11407–11422

Origin of thermal modal instabilities in large mode area fiber amplifiers

B. Ward, C. Robin, and I. Dajani  »View Author Affiliations

Optics Express, Vol. 20, Issue 10, pp. 11407-11422 (2012)

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We present a dynamic model of thermal modal instability in large mode area fiber amplifiers. This model allows the pump and signal optical intensity distributions to apply a time-varying heat load distribution within the fiber. This influences the temperature distribution that modifies the optical distributions through the thermo-optic effect thus creating a feedback loop that gives rise to time-dependent modal instability. We describe different regimes of operation for a representative fiber design. We find qualitative agreement between simulation results and experimental results obtained with a different fiber including the time-dependent behavior of the instability and the effects of different cooling configurations on the threshold. We describe the physical processes responsible for the onset of the instability and suggest possible mitigation approaches.

© 2012 OSA

OCIS Codes
(140.3510) Lasers and laser optics : Lasers, fiber
(140.4480) Lasers and laser optics : Optical amplifiers
(140.6810) Lasers and laser optics : Thermal effects
(190.4370) Nonlinear optics : Nonlinear optics, fibers
(060.5295) Fiber optics and optical communications : Photonic crystal fibers

ToC Category:
Lasers and Laser Optics

Original Manuscript: March 19, 2012
Revised Manuscript: April 26, 2012
Manuscript Accepted: April 26, 2012
Published: May 3, 2012

Virtual Issues
June 11, 2012 Spotlight on Optics

B. Ward, C. Robin, and I. Dajani, "Origin of thermal modal instabilities in large mode area fiber amplifiers," Opt. Express 20, 11407-11422 (2012)

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  1. C. Wirth, T. Schreiber, M. Rekas, I. Tsybin, T. Peschel, R. Eberhardt, and A. Tünnermann, “High-power linear-polarized narrow linewidth photonic crystal fiber amplifier,” Proc. SPIE7580, 75801H, 75801H-6 (2010), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-17-13240 .
  2. T. Eidam, S. Hädrich, F. Jansen, F. Stutzki, J. Rothhardt, H. Carstens, C. Jauregui, J. Limpert, and A. Tünnermann, “Preferential gain photonic-crystal fiber for mode stabilization at high average powers,” Opt. Express 19(9), 8656–8661 (2011), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-9-8656 . [CrossRef] [PubMed]
  3. M. Laurila, M. M. Jørgensen, K. R. Hansen, T. T. Alkeskjold, J. Broeng, and J. Lægsgaard, “Distributed mode filtering rod fiber amplifier delivering 292W with improved mode stability,” Opt. Express 20(5), 5742–5753 (2012), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-5-5742 . [CrossRef] [PubMed]
  4. T. Eidam, C. Wirth, C. Jauregui, F. Stutzki, F. Jansen, H.-J. Otto, O. Schmidt, T. Schreiber, J. Limpert, and A. Tünnermann, “Experimental observations of the threshold-like onset of mode instabilities in high power fiber amplifiers,” Opt. Express 19(14), 13218–13224 (2011), http://www.opticsinfobase.org/abstract.cfm?URI=oe-19-14-13218 . [CrossRef] [PubMed]
  5. C. Jauregui, T. Eidam, J. Limpert, and A. Tünnermann, “The impact of modal interference on the beam quality of high-power fiber amplifiers,” Opt. Express 19(4), 3258–3271 (2011), http://www.opticsinfobase.org/abstract.cfm?URI=oe-19-4-3258 . [CrossRef] [PubMed]
  6. A. V. Smith and J. J. Smith, “Mode instability in high power fiber amplifiers,” Opt. Express 19(11), 10180–10192 (2011), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-19-11-10180 . [CrossRef] [PubMed]
  7. C. Jauregui, T. Eidam, H.-J. Otto, F. Stutzki, F. Jansen, J. Limpert, and A. Tünnermann, “Temperature-induced index gratings and their impact on mode instabilities in high-power fiber laser systems,” Opt. Express 20(1), 440–451 (2012), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-1-440 . [CrossRef] [PubMed]
  8. K. R. Hansen, T. T. Alkeskjold, J. Broeng, and J. Lægsgaard, “Thermo-optical effects in high-power ytterbium-doped fiber amplifiers,” Opt. Express 19(24), 23965–23980 (2011), http://www.opticsinfobase.org/abstract.cfm?URI=oe-19-24-23965 . [CrossRef] [PubMed]
  9. A. A. Fotiadi, O. L. Antipov, and P. M’egret, “Resonantly induced refractive index changes in Yb-doped fibers: the origin, properties and application for all-fiber coherent beam combining,” in Frontiers in Guided Wave Optics and Optoelectronics, B. Pal, ed. (Intec, 2010), 209–234.
  10. F. Jansen, F. Stutzki, H.-J. Otto, T. Eidam, A. Liem, C. Jauregui, J. Limpert, and A. Tünnermann, “Thermally induced waveguide changes in active fibers,” Opt. Express 20(4), 3997–4008 (2012), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-4-3997 . [CrossRef] [PubMed]
  11. C. Robin and I. Dajani, “Acoustically segmented photonic crystal fiber for single-frequency high-power laser applications,” Opt. Lett. 36(14), 2641–2643 (2011), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-36-14-2641 . [CrossRef] [PubMed]
  12. F. Stutzki, H.-J. Otto, F. Jansen, C. Gaida, C. Jauregui, J. Limpert, and A. Tünnermann, “High-speed modal decomposition of mode instabilities in high-power fiber lasers,” Opt. Lett. 36(23), 4572–4574 (2011), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-36-23-4572 . [CrossRef] [PubMed]

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