Abstract

Photodarkening in Yb doped fibers was examined at 633 nm in-situ during cladding pumping at 915 nm with varying pump powers and with no indication of an onset threshold. For the first time, the partial bleaching of the photodarkening loss by the pump power itself was observed. We found the relaxation to well-defined equilibrium states of the core excess loss, depending on the Yb inversion. From the dependence of the measured rate constant on the density of excited Yb ions we conclude, that on average 3 to 4 excited Yb ions create or bleach one color center responsible for the core excess loss.

© 2007 Optical Society of America

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References

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    [CrossRef] [PubMed]
  4. I. Manek-Hönninger, J. Boullet, T. Cardinal, F. Guillen, M. Podgorski, R. Bello Doua, and F. Salin, "Photodarkening and photobleaching of an ytterbium-doped silica double-clad LMA fiber," Opt. Express 15, 1606-1611 (2007).
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  5. B. Morasse, S. Chatigny, E. Gagnon, C. Hovington, J.-P. Martin, and J.-P. De Sandro, "Low photodarkening single cladding ytterbium fibre amplifier," in Fiber Lasers IV: Technology, Systems, and Applications, D. J. Harter, A. Tünnermann, J. Broeng, and C. Headley, eds., Proc. SPIE 6453, 64530H-1-9 (2007).
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    [CrossRef]
  11. J. Kirchhof, S. Unger, and A. Schwuchow, "Properties of Yb-doped materials for solid and microstructured high power fiber lasers," in Proceedings of ICMAT 2007 Symposium on Microstructured and Nanostructured Optical Fibers, Singapore, 1-6 July, 2007.
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    [CrossRef]

2007

2006

J. J. Koponen, M. J. Söderlund, H. J. Hoffmann, and S. K. T. Tammela, "Measuring photodarkening from single-mode ytterbium doped silica fibers," Opt. Express 14,11539-11544 (2006).
[CrossRef] [PubMed]

J. Kirchhof, S. Unger, A. Schwuchow, S. Grimm, and V. Reichel, "Materials for high-power fiber lasers," J. Non-Cryst. Solids 352, 2399-2403 (2006).
[CrossRef]

1997

R. Paschotta, J. Nilsson, P. R. Barber, J. E. Caplen, A. C. Tropper, and D. C. Hanna, "Lifetime quenching in Yb-doped fibers," Opt. Commun. 136, 375-378 (1997).
[CrossRef]

1994

1993

1980

C. P. Lindsey and G. D. Patterson, "Detailed comparison of the Williams-Watts and Cole-Davidson functions," J. Chem. Phys. 73, 3348-3357 (1980).
[CrossRef]

J. Chem. Phys.

C. P. Lindsey and G. D. Patterson, "Detailed comparison of the Williams-Watts and Cole-Davidson functions," J. Chem. Phys. 73, 3348-3357 (1980).
[CrossRef]

J. Non-Cryst. Solids

J. Kirchhof, S. Unger, A. Schwuchow, S. Grimm, and V. Reichel, "Materials for high-power fiber lasers," J. Non-Cryst. Solids 352, 2399-2403 (2006).
[CrossRef]

Opt. Commun.

R. Paschotta, J. Nilsson, P. R. Barber, J. E. Caplen, A. C. Tropper, and D. C. Hanna, "Lifetime quenching in Yb-doped fibers," Opt. Commun. 136, 375-378 (1997).
[CrossRef]

Opt. Express

Opt. Lett.

Other

B. Morasse, S. Chatigny, E. Gagnon, C. Hovington, J.-P. Martin, and J.-P. De Sandro, "Low photodarkening single cladding ytterbium fibre amplifier," in Fiber Lasers IV: Technology, Systems, and Applications, D. J. Harter, A. Tünnermann, J. Broeng, and C. Headley, eds., Proc. SPIE 6453, 64530H-1-9 (2007).
[CrossRef]

J. Kirchhof, S. Unger, and A. Schwuchow, "Properties of Yb-doped materials for solid and microstructured high power fiber lasers," in Proceedings of ICMAT 2007 Symposium on Microstructured and Nanostructured Optical Fibers, Singapore, 1-6 July, 2007.

J. Jasapara, M. Andrejco, D. DiGiovanni, and R. Windeler, "Effect of heat and H2 gas on the photodarkening of Yb3+ fibers," in Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies 2006, Technical Digest (Optical Society of America, Washington, DC, 2006), CTuQ5.

A. V. Shubin, M. V. Yashkov, M. A. Melkumov, S. A. Smirnow, I. A. Bufetov, and E. M. Dianov, "Photodarkening of aluminosilicate and phosphosilicate Yb-doped fibers," in Conf. Digest of CLEO Europe-EQEC 2007, CJ3-1-THU.

J. Koponen, M. Söderlund, H. J. Hoffman, D. Kliner, and J. Koplow, "Photodarkening Measurements in Large-Mode-Area Fibers," in Fiber Lasers IV: Technology, Systems, and Applications, D. J. Harter,A. Tünnermann, J. Broeng, and C. Headley, eds., Proc. SPIE 6453, 64531E-1-11 (2007).
[CrossRef]

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Figures (5)

Fig 1.
Fig 1.

(a) Experimental setup for the measurement of photodarkening; (b) Probe transmission measured at fiber #4 (L = 5 cm) in-situ during cladding pumping with different initial pump powers: 1 W (lilac), 1.8 W (cyan), 2.1 W (green), 3.7 W (red) and 6.1 W (blue); after application of the initial pump power for a sufficient time, the Yb fiber core was “fully darkened” by a pump power of 13.2 W (steep decrease of the transmission).

Fig. 2.
Fig. 2.

Core excess loss of fiber #3 (length L=1cm) for stepwise variation of the pump power; (a): darkening (red) with 1.0, 2.1, 3.7, 6.1, 10, 13.2 W, (b): bleaching (green) with 10, 6.1, 3.7, 2.1, 1.0, 0.6 W (the last reduction of the pump power was applied at 431 min); the stretched exponential functions determined by the fitting procedure are also shown as thin dashed black lines.

Fig. 3.
Fig. 3.

Photodarkening (red) and photobleaching (green, after darkening with a higher pump power) of fiber #3 with the same pump power of 3.7 W (sections of Fig. 2a and 2b with shifted time scale); the stretched exponential functions determined by the fitting procedure are shown as thin dashed black lines; in both cases the core excess loss converges to the equilibrium value α eq ≈ 530 dB/m for t → ∞ (dotted line).

Fig. 4.
Fig. 4.

Rate constant τ-1 in a log-log plot (a) and equilibrium core excess loss α eq in a linear plot (b) as a function of the Yb inversion, determined for stepwise photodarkening (full red circles) and photobleaching (green crosses) of fiber #3 (measurements and fitting curves see Fig. 2); the values determined for “fresh” fibers (α 0 = 0) in a one-step darkening process are also included (open red squares). The dashed lines in (a) are linear fits.

Fig. 5.
Fig. 5.

Rate constant τ-1 in a log-log plot (a) and equilibrium core excess loss α eq in a linear plot (b) in dependence on the density of excited Yb ions [Yb*] for the fibers investigated (see Table 1): #1 (blue), #2 (cyan), #3 (olive), #4 (orange), and #5 (magenta). The solid lines are linear fits to the measured data.

Tables (1)

Tables Icon

Table 1. Fiber sample number, density of ytterbium ions N, core NA, Yb3+ near infrared fluorescence lifetime τ, and fiber background loss α at 1200 and 633 nm, respectively.

Equations (1)

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α ( t ) = ( α 0 α eq ) exp [ ( ( t t 0 ) τ ) β ] + α eq .

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