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Optics Express

Optics Express

  • Editor: Andrew M. Weiner
  • Vol. 21, Iss. 16 — Aug. 12, 2013
  • pp: 18927–18936
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Inner cladding microstructuration based on symmetry reduction for improvement of singlemode robustness in VLMA fiber

Romain Dauliat, Dmitry Gaponov, Aurélien Benoit, François Salin, Kay Schuster, Raphaël Jamier, and Philippe Roy  »View Author Affiliations


Optics Express, Vol. 21, Issue 16, pp. 18927-18936 (2013)
http://dx.doi.org/10.1364/OE.21.018927


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Abstract

Very large mode area, active optical fibers with a low high order mode content in the actively doped core region were designed by removing the inner cladding symmetry. The relevance of the numerical approach is demonstrated here by the investigation of a standard air-silica Large Pitch Fiber, used as a reference. A detailed study of all-solid structures is also performed. Finally, we propose new kinds of geometry for 50 μm core, all-solid microstructured fibers enabling a robust singlemode laser emission from 400 nm to 2200 nm.

© 2013 OSA

1. Introduction

2. Definition of our simulation procedure - Application to an air/silica LPFs chosen as reference

Fig. 1. (a) 2D refractive index repartition of the air/silica LPF described in [2]. The gain region is in red, the pure silica in blue and the air holes in yellow. (b) Overlap factor of the fundamental mode (solid lines) and modal discrimination (dashed lines) computed for the air/silica LPF. Calculations have been done for three air-clad diameters: 170 μm (black), 180 μm (red), and 190 μm (blue) and various ratio d/Λ. Insets: computed intensity distributions corresponding to the fundamental mode coupling (top), and the most disturbing HOM (bottom).

3. Design of all-solid microstructured fibers

In this section, we discuss an approach aiming to improve the HOMs discrimination in microstructured leaky fibers. Designs investigated hereinafter are based on an array of hexagonal cells as depicted in Table 1 and Table 2. In leaky fibers, the refractive index of the core has to match that of the background material in order to provide efficient leakage channels. In this way, for current air/silica fibers, the refractive index of the gain medium match that of the pure silica. Here we chose to relieve the restriction on the core refractive index (RI) and to increase the RI of the background material (silica RI is increased using an index-raising dopant). This made it possible to introduce a strong concentration of rare-earth ions (RE) into the fiber core, thus reducing the required fiber length and pushing away the non linear effects. Moreover, it offers a potential for high linear gain and finally, an appropriate composition of the core material can be envisaged to efficiently compete with photodarkening.

Table 1. On the left side, the structures are numbered and named. The middle column depicts the distribution of the fiber refractive index, based on which the actively (passively) doped region is in red (clear blue) and pure silica in dark blue. On the right side, a representation of the modal confinement for the first 300 guided modes is shown for different core diameters: 50 μm (in black), 60 μm (in red) and 70 μm (in blue). The intensity distributions of the FM and the most disturbing HOM are depicted in the inset.

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Table 2. Similar to Table 1 with three structures based on symmetry reduction.

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3.1. HOM leakage behavior

3.2. Reduction of cladding symmetry

Fig. 2 Spectral evolution of the modal discrimination for the whole 50 μm all-solid structures proposed: (a) LPF structures (air/silica LPF and structures n°2 and 4), (b) Vortex (n°3), hexagonal symmetry free (n°5) and aperiodic quasi-pentagonal (n°6) fibers. The latter two fibers feature two different refractive index contrasts.

4. Conclusion

Acknowledgments

This work, conducted under the AVANTAGE project, was co-funded by the European Union and Eolite Lasers. EC is involved in the Région Limousin with the ”Fonds européen de développement économique et régional”.

References and links

1.

D. Gapontsev, “6kW CW single mode ytterbium fiber laser in all-fiber format,” Proc. Solid State and Diode Laser Technology Review (2008).

2.

F. Stutzki, F. Jansen, A. Liem, C. Jauregui, J. Limpert, and A. Tünnermann, “26mJ, 130W Q-switched fiber laser system with near-diffraction-limited beam quality,” Opt. Lett. 37(6), 1073–1075 (2012). [CrossRef] [PubMed]

3.

P. F. Moulton, T. Ehrenreich, R. Leveille, I. Majid, K. Tankala, and G. Rines, “1-kW, all-glass Tm : fiber laser,” Proc. of SPIE 7580 , paper 7580112 (2010).

4.

S. Jetschke, S. Unger, A. Schwuchow, M. Leich, and J. Kirchhof, “Efficient Yb laser fibers with low photodark-ening by optimization of the core composition,” Opt. Express 16(20), 15540–15545 (2008). [CrossRef] [PubMed]

5.

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). [CrossRef] [PubMed]

6.

K. R. Hansen, T. T. Alkeskjold, J. Broeng, and J. Lægsgaard, “Theoretical analysis of mode instability in high-power fiber amplifiers,” Opt. Express 21(2), 3997–4008 (2013). [CrossRef]

7.

F. Stutzki, F. Jansen, C. Jauregui, J. Limpert, and A. Tünnermann, “Non-hexagonal large-pitch fibers for enhanced mode discrimination,” Opt. Express 19(13), 12081–12086 (2011). [CrossRef] [PubMed]

8.

M. M. Jørgensen, S. R. Petersen, M. Laurila, J. Lægsgaard, and T. T. Alkeskjold, “Optimizing single mode robustness of the distributed modal filtering rod fiber amplifier,” Opt. Express 20(7), 7263–7273 (2012). [CrossRef] [PubMed]

9.

F. Jansen, F. Stutzki, H. Otto, C. Jauregui, J. Limpert, and A. Tünnermann, “High-power thermally guiding index-antiguiding-core fibers,” Opt. Lett. 38(4), 510–512 (2013). [CrossRef] [PubMed]

10.

J. Limpert, F. Stutzki, F. Jansen, H. J. Otto, T. Eidam, C. Jauregui, and A. Tünnermann, “Yb-doped large-pitch fibres: effective single-mode operation based on higher-order mode delocalisation,” Light: Science & Applications 1, e8, (2012). [CrossRef]

11.

F. Jansen, F. Stutzki, C. Jauregui, J. Limpert, and A. Tünnermann, “Avoided crossings in photonic crystal fibers,” Opt. Express 19(14), 13578–13589 (2011). [CrossRef] [PubMed]

12.

R. Dauliat, D. A. Gaponov, A. Benoit, F. Salin, K. Schuster, S. Jetschke, S. Grimm, and P. Roy, “Ytterbium doped all solid large pitch fiber made from powder sintering and vitrification,” International Conference on Fibre Optics and Photonics - OSA Technical Digest, paper TPo.7 (2012). [CrossRef]

13.

J. M. Fini, “Improved symmetry analysis of many-moded microstructure optical fibers,” J. Opt. Soc. Am. B 21(8), 1431–1436 (2004). [CrossRef]

14.

P. McIsaac, “Symmetry-induced modal characteristics of uniform waveguides,” IEEE Trans. Microwave Theory Tech. 23(5), 421–433 (1975). [CrossRef]

15.

R. Guobin, W. Zhi, L. Shuqin, and J. Shuisheng, “Mode classification and degeneracy in photonic crystal fibers,” Opt. Express 11(11), 1310–1321 (2003). [CrossRef] [PubMed]

16.

M. Steel, “Reflection symmetry and mode transversality in microstructured fibers,” Opt. Express 12(8), 1497–509 (2004). [CrossRef] [PubMed]

17.

P. M. Agruzov, K. V Dukelskii, and V. S. Shevandin, “Three types of microstructured large core fibers : development and investigation,” Conference on Lasers and Electro-Optics, paper CE.P.28 (2009).

18.

V. V Demidov, K. V Dukelskii, and V. S. Shevandin, “Novel bend-resistant design of single-mode microstructured fibers,” Conference on Lasers and Electro-Optics, paper CE.P35 (2011).

19.

M.-Y. Chen, Y. Li, J. Zhou, and Y.-K. Zhang, “Design of asymmetric large-mode area optical fiber with low bending loss,” J. of Lightwave Technol. 31(3), 476–481 (2013). [CrossRef]

20.

J. Limpert, “Large-pitch fibers: pushing very large mode areas to highest powers,” International Conference on Fibre Optics and Photonics - OSA Technical Digest, paper T2A.1 (2012). [CrossRef]

OCIS Codes
(060.2280) Fiber optics and optical communications : Fiber design and fabrication
(060.2430) Fiber optics and optical communications : Fibers, single-mode
(140.3510) Lasers and laser optics : Lasers, fiber
(060.4005) Fiber optics and optical communications : Microstructured fibers

ToC Category:
Fiber Optics and Optical Communications

History
Original Manuscript: May 31, 2013
Revised Manuscript: July 20, 2013
Manuscript Accepted: July 22, 2013
Published: August 1, 2013

Citation
Romain Dauliat, Dmitry Gaponov, Aurélien Benoit, François Salin, Kay Schuster, Raphaël Jamier, and Philippe Roy, "Inner cladding microstructuration based on symmetry reduction for improvement of singlemode robustness in VLMA fiber," Opt. Express 21, 18927-18936 (2013)
http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-21-16-18927


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References

  1. D. Gapontsev, “6kW CW single mode ytterbium fiber laser in all-fiber format,” Proc. Solid State and Diode Laser Technology Review (2008).
  2. F. Stutzki, F. Jansen, A. Liem, C. Jauregui, J. Limpert, and A. Tünnermann, “26mJ, 130W Q-switched fiber laser system with near-diffraction-limited beam quality,” Opt. Lett.37(6), 1073–1075 (2012). [CrossRef] [PubMed]
  3. P. F. Moulton, T. Ehrenreich, R. Leveille, I. Majid, K. Tankala, and G. Rines, “1-kW, all-glass Tm : fiber laser,” Proc. of SPIE 7580, paper 7580112 (2010).
  4. S. Jetschke, S. Unger, A. Schwuchow, M. Leich, and J. Kirchhof, “Efficient Yb laser fibers with low photodark-ening by optimization of the core composition,” Opt. Express16(20), 15540–15545 (2008). [CrossRef] [PubMed]
  5. 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. Express19(14), 13218–13224 (2011). [CrossRef] [PubMed]
  6. K. R. Hansen, T. T. Alkeskjold, J. Broeng, and J. Lægsgaard, “Theoretical analysis of mode instability in high-power fiber amplifiers,” Opt. Express21(2), 3997–4008 (2013). [CrossRef]
  7. F. Stutzki, F. Jansen, C. Jauregui, J. Limpert, and A. Tünnermann, “Non-hexagonal large-pitch fibers for enhanced mode discrimination,” Opt. Express19(13), 12081–12086 (2011). [CrossRef] [PubMed]
  8. M. M. Jørgensen, S. R. Petersen, M. Laurila, J. Lægsgaard, and T. T. Alkeskjold, “Optimizing single mode robustness of the distributed modal filtering rod fiber amplifier,” Opt. Express20(7), 7263–7273 (2012). [CrossRef] [PubMed]
  9. F. Jansen, F. Stutzki, H. Otto, C. Jauregui, J. Limpert, and A. Tünnermann, “High-power thermally guiding index-antiguiding-core fibers,” Opt. Lett.38(4), 510–512 (2013). [CrossRef] [PubMed]
  10. J. Limpert, F. Stutzki, F. Jansen, H. J. Otto, T. Eidam, C. Jauregui, and A. Tünnermann, “Yb-doped large-pitch fibres: effective single-mode operation based on higher-order mode delocalisation,” Light: Science & Applications1, e8, (2012). [CrossRef]
  11. F. Jansen, F. Stutzki, C. Jauregui, J. Limpert, and A. Tünnermann, “Avoided crossings in photonic crystal fibers,” Opt. Express19(14), 13578–13589 (2011). [CrossRef] [PubMed]
  12. R. Dauliat, D. A. Gaponov, A. Benoit, F. Salin, K. Schuster, S. Jetschke, S. Grimm, and P. Roy, “Ytterbium doped all solid large pitch fiber made from powder sintering and vitrification,” International Conference on Fibre Optics and Photonics - OSA Technical Digest, paper TPo.7 (2012). [CrossRef]
  13. J. M. Fini, “Improved symmetry analysis of many-moded microstructure optical fibers,” J. Opt. Soc. Am. B21(8), 1431–1436 (2004). [CrossRef]
  14. P. McIsaac, “Symmetry-induced modal characteristics of uniform waveguides,” IEEE Trans. Microwave Theory Tech.23(5), 421–433 (1975). [CrossRef]
  15. R. Guobin, W. Zhi, L. Shuqin, and J. Shuisheng, “Mode classification and degeneracy in photonic crystal fibers,” Opt. Express11(11), 1310–1321 (2003). [CrossRef] [PubMed]
  16. M. Steel, “Reflection symmetry and mode transversality in microstructured fibers,” Opt. Express12(8), 1497–509 (2004). [CrossRef] [PubMed]
  17. P. M. Agruzov, K. V Dukelskii, and V. S. Shevandin, “Three types of microstructured large core fibers : development and investigation,” Conference on Lasers and Electro-Optics, paper CE.P.28 (2009).
  18. V. V Demidov, K. V Dukelskii, and V. S. Shevandin, “Novel bend-resistant design of single-mode microstructured fibers,” Conference on Lasers and Electro-Optics, paper CE.P35 (2011).
  19. M.-Y. Chen, Y. Li, J. Zhou, and Y.-K. Zhang, “Design of asymmetric large-mode area optical fiber with low bending loss,” J. of Lightwave Technol.31(3), 476–481 (2013). [CrossRef]
  20. J. Limpert, “Large-pitch fibers: pushing very large mode areas to highest powers,” International Conference on Fibre Optics and Photonics - OSA Technical Digest, paper T2A.1 (2012). [CrossRef]

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