Abstract

Single-pass amplification using rod-type fibers has become a common route to pulsed laser sources around 1030 nm with high average and peak power. Average-power scaling is currently limited by the dynamic thermo-optic phenomenon of “transverse mode instability.” In comparison, double-pass amplifier configurations have not been extensively studied. Recent theoretical and experimental work has shown both static and dynamic mode degradation phenomena, including an unexpected nonlinear polarization rotation effect. Here we present new results obtained with a modified setup using polarization filtering between the first and the second pass. We obtain up to 113 W output power, i.e., more than 40 dB of amplification from a single amplifier module seeded by 10 mW of 20 ps/20 MHz/1030 nm pulses. We observe excellent beam quality and polarization extinction ratio. Finally, we investigate a wide range of seed powers and report a strong increase in the static mode deformation threshold with decreasing seed power. The experimental results are corroborated by numerical simulations.

© 2020 Optical Society of America

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References

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  1. D. J. Richardson, J. Nilsson, and W. A. Clarkson, “High power fiber lasers: current status and future perspectives,” J. Opt. Soc. Am. B 27, B63–B92 (2010).
    [Crossref]
  2. C. Jauregui, J. Limpert, and A. Tünnermann, “High-power fibre lasers,” Nat. Photonics 7, 861 (2013).
    [Crossref]
  3. M. N. Zervas and C. A. Codemard, “High power fiber lasers: a review,” IEEE J. Sel. Top. Quantum Electron. 20, 219–241 (2014).
    [Crossref]
  4. T. Eidam, S. Hanf, E. Seise, T. V. Andersen, T. Gabler, C. Wirth, T. Schreiber, J. Limpert, and A. Tünnermann, “Femtosecond fiber CPA system emitting 830  W average output power,” Opt. Lett. 35, 94–96 (2010).
    [Crossref]
  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, 13218–13224 (2011).
    [Crossref]
  6. A. V. Smith and J. J. Smith, “Mode instability in high power fiber amplifiers,” Opt. Express 19, 10180–10192 (2011).
    [Crossref]
  7. C. Jauregui, T. Eidam, J. Limpert, and A. Tünnermann, “Impact of modal interference on the beam quality of high-power fiber amplifiers,” Opt. Express 19, 3258–3271 (2011).
    [Crossref]
  8. C. Jauregui, T. Eidam, H.-J. Otto, F. Stutzki, F. Jansen, J. Limpert, and A. Tünnermann, “Physical origin of mode instabilities in high-power fiber laser systems,” Opt. Express 20, 12912–12925 (2012).
    [Crossref]
  9. K. R. Hansen, T. T. Alkeskjold, J. Broeng, and J. Lægsgaard, “Thermally induced mode coupling in rare-earth doped fiber amplifiers,” Opt. Lett. 37, 2382–2384 (2012).
    [Crossref]
  10. K. R. Hansen, T. T. Alkeskjold, J. Broeng, and J. Lægsgaard, “Theoretical analysis of mode instability in high-power fiber amplifiers,” Opt. Express 21, 1944–1971 (2013).
    [Crossref]
  11. B. G. Ward, “Modeling of transient modal instability in fiber amplifiers,” Opt. Express 21, 12053–12067 (2013).
    [Crossref]
  12. L. Dong, “Stimulated thermal Rayleigh scattering in optical fibers,” Opt. Express 21, 2642–2656 (2013).
    [Crossref]
  13. C. Jauregui, H.-J. Otto, F. Stutzki, J. Limpert, and A. Tünnermann, “Simplified modelling the mode instability threshold of high power fiber amplifiers in the presence of photodarkening,” Opt. Express 23, 20203–20218 (2015).
    [Crossref]
  14. H.-J. Otto, N. Modsching, C. Jauregui, J. Limpert, and A. Tünnermann, “Impact of photodarkening on the mode instability threshold,” Opt. Express 23, 15265–15277 (2015).
    [Crossref]
  15. J. Lægsgaard, “Static thermo-optic instability in double-pass fiber amplifiers,” Opt. Express 24, 13429–13443 (2016).
    [Crossref]
  16. C. Stihler, H.-J. Otto, C. Jauregui, J. Limpert, and A. Tünnermann, “Experimental investigation of transverse mode instabilities in a double-pass yb-doped rod-type fiber amplifier,” Proc. SPIE 10083, 100830R (2017).
    [Crossref]
  17. J.-F. Lupi, M. M. Johansen, M. Michieletto, and J. Lægsgaard, “Static and dynamic mode coupling in a double-pass rod-type fiber amplifier,” Opt. Lett. 43, 5535–5538 (2018).
    [Crossref]
  18. Y. Zaouter, F. Guichard, L. Daniault, M. Hanna, F. Morin, C. Hönninger, E. Mottay, F. Druon, and P. Georges, “Femtosecond fiber chirped- and divided-pulse amplification system,” Opt. Lett. 38, 106–108 (2013).
    [Crossref]
  19. R. Tao, X. Wang, and P. Zhou, “Comprehensive theoretical study of mode instability in high-power fiber lasers by employing a universal model and its implications,” IEEE J. Sel. Top. Quantum Electron. 24, 1–19 (2018).
    [Crossref]
  20. C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “The impact of pump-power noise on transverse mode instabilities,” Proc. SPIE 10897, 1089703 (2019).
    [Crossref]
  21. C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “Pump-power-noise influence on mode instabilities in high-power fiber laser systems,” in The European Conference on Lasers and Electro-Optics (Optical Society of America, 2019), paper cj_4_6.
  22. M. M. Johansen, M. Laurila, M. D. Maack, D. Noordegraaf, C. Jakobsen, T. T. Alkeskjold, and J. Lægsgaard, “Frequency resolved transverse mode instability in rod fiber amplifiers,” Opt. Express 21, 21847–21856 (2013).
    [Crossref]
  23. T. T. Alkeskjold, M. Laurila, L. Scolari, and J. Broeng, “Single-mode ytterbium-doped large-mode-area photonic bandgap rod fiber amplifier,” Opt. Express 19, 7398–7409 (2011).
    [Crossref]
  24. A. V. Smith and J. J. Smith, “Increasing mode instability thresholds of fiber amplifiers by gain saturation,” Opt. Express 21, 15168–15182 (2013).
    [Crossref]
  25. K. R. Hansen and J. Lægsgaard, “Impact of gain saturation on the mode instability threshold in high-power fiber amplifiers,” Opt. Express 22, 11267–11278 (2014).
    [Crossref]

2019 (1)

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “The impact of pump-power noise on transverse mode instabilities,” Proc. SPIE 10897, 1089703 (2019).
[Crossref]

2018 (2)

R. Tao, X. Wang, and P. Zhou, “Comprehensive theoretical study of mode instability in high-power fiber lasers by employing a universal model and its implications,” IEEE J. Sel. Top. Quantum Electron. 24, 1–19 (2018).
[Crossref]

J.-F. Lupi, M. M. Johansen, M. Michieletto, and J. Lægsgaard, “Static and dynamic mode coupling in a double-pass rod-type fiber amplifier,” Opt. Lett. 43, 5535–5538 (2018).
[Crossref]

2017 (1)

C. Stihler, H.-J. Otto, C. Jauregui, J. Limpert, and A. Tünnermann, “Experimental investigation of transverse mode instabilities in a double-pass yb-doped rod-type fiber amplifier,” Proc. SPIE 10083, 100830R (2017).
[Crossref]

2016 (1)

2015 (2)

2014 (2)

M. N. Zervas and C. A. Codemard, “High power fiber lasers: a review,” IEEE J. Sel. Top. Quantum Electron. 20, 219–241 (2014).
[Crossref]

K. R. Hansen and J. Lægsgaard, “Impact of gain saturation on the mode instability threshold in high-power fiber amplifiers,” Opt. Express 22, 11267–11278 (2014).
[Crossref]

2013 (7)

2012 (2)

2011 (4)

2010 (2)

Alkeskjold, T. T.

Andersen, T. V.

Broeng, J.

Clarkson, W. A.

Codemard, C. A.

M. N. Zervas and C. A. Codemard, “High power fiber lasers: a review,” IEEE J. Sel. Top. Quantum Electron. 20, 219–241 (2014).
[Crossref]

Daniault, L.

Dong, L.

Druon, F.

Eidam, T.

Gabler, T.

Georges, P.

Guichard, F.

Hanf, S.

Hanna, M.

Hansen, K. R.

Hönninger, C.

Jakobsen, C.

Jansen, F.

Jauregui, C.

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “The impact of pump-power noise on transverse mode instabilities,” Proc. SPIE 10897, 1089703 (2019).
[Crossref]

C. Stihler, H.-J. Otto, C. Jauregui, J. Limpert, and A. Tünnermann, “Experimental investigation of transverse mode instabilities in a double-pass yb-doped rod-type fiber amplifier,” Proc. SPIE 10083, 100830R (2017).
[Crossref]

H.-J. Otto, N. Modsching, C. Jauregui, J. Limpert, and A. Tünnermann, “Impact of photodarkening on the mode instability threshold,” Opt. Express 23, 15265–15277 (2015).
[Crossref]

C. Jauregui, H.-J. Otto, F. Stutzki, J. Limpert, and A. Tünnermann, “Simplified modelling the mode instability threshold of high power fiber amplifiers in the presence of photodarkening,” Opt. Express 23, 20203–20218 (2015).
[Crossref]

C. Jauregui, J. Limpert, and A. Tünnermann, “High-power fibre lasers,” Nat. Photonics 7, 861 (2013).
[Crossref]

C. Jauregui, T. Eidam, H.-J. Otto, F. Stutzki, F. Jansen, J. Limpert, and A. Tünnermann, “Physical origin of mode instabilities in high-power fiber laser systems,” Opt. Express 20, 12912–12925 (2012).
[Crossref]

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, 13218–13224 (2011).
[Crossref]

C. Jauregui, T. Eidam, J. Limpert, and A. Tünnermann, “Impact of modal interference on the beam quality of high-power fiber amplifiers,” Opt. Express 19, 3258–3271 (2011).
[Crossref]

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “Pump-power-noise influence on mode instabilities in high-power fiber laser systems,” in The European Conference on Lasers and Electro-Optics (Optical Society of America, 2019), paper cj_4_6.

Johansen, M. M.

Lægsgaard, J.

Laurila, M.

Limpert, J.

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “The impact of pump-power noise on transverse mode instabilities,” Proc. SPIE 10897, 1089703 (2019).
[Crossref]

C. Stihler, H.-J. Otto, C. Jauregui, J. Limpert, and A. Tünnermann, “Experimental investigation of transverse mode instabilities in a double-pass yb-doped rod-type fiber amplifier,” Proc. SPIE 10083, 100830R (2017).
[Crossref]

H.-J. Otto, N. Modsching, C. Jauregui, J. Limpert, and A. Tünnermann, “Impact of photodarkening on the mode instability threshold,” Opt. Express 23, 15265–15277 (2015).
[Crossref]

C. Jauregui, H.-J. Otto, F. Stutzki, J. Limpert, and A. Tünnermann, “Simplified modelling the mode instability threshold of high power fiber amplifiers in the presence of photodarkening,” Opt. Express 23, 20203–20218 (2015).
[Crossref]

C. Jauregui, J. Limpert, and A. Tünnermann, “High-power fibre lasers,” Nat. Photonics 7, 861 (2013).
[Crossref]

C. Jauregui, T. Eidam, H.-J. Otto, F. Stutzki, F. Jansen, J. Limpert, and A. Tünnermann, “Physical origin of mode instabilities in high-power fiber laser systems,” Opt. Express 20, 12912–12925 (2012).
[Crossref]

C. Jauregui, T. Eidam, J. Limpert, and A. Tünnermann, “Impact of modal interference on the beam quality of high-power fiber amplifiers,” Opt. Express 19, 3258–3271 (2011).
[Crossref]

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, 13218–13224 (2011).
[Crossref]

T. Eidam, S. Hanf, E. Seise, T. V. Andersen, T. Gabler, C. Wirth, T. Schreiber, J. Limpert, and A. Tünnermann, “Femtosecond fiber CPA system emitting 830  W average output power,” Opt. Lett. 35, 94–96 (2010).
[Crossref]

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “Pump-power-noise influence on mode instabilities in high-power fiber laser systems,” in The European Conference on Lasers and Electro-Optics (Optical Society of America, 2019), paper cj_4_6.

Lupi, J.-F.

Maack, M. D.

Michieletto, M.

Modsching, N.

Morin, F.

Mottay, E.

Nilsson, J.

Noordegraaf, D.

Otto, H.-J.

Richardson, D. J.

Schmidt, O.

Schreiber, T.

Scolari, L.

Seise, E.

Smith, A. V.

Smith, J. J.

Stihler, C.

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “The impact of pump-power noise on transverse mode instabilities,” Proc. SPIE 10897, 1089703 (2019).
[Crossref]

C. Stihler, H.-J. Otto, C. Jauregui, J. Limpert, and A. Tünnermann, “Experimental investigation of transverse mode instabilities in a double-pass yb-doped rod-type fiber amplifier,” Proc. SPIE 10083, 100830R (2017).
[Crossref]

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “Pump-power-noise influence on mode instabilities in high-power fiber laser systems,” in The European Conference on Lasers and Electro-Optics (Optical Society of America, 2019), paper cj_4_6.

Stutzki, F.

Tao, R.

R. Tao, X. Wang, and P. Zhou, “Comprehensive theoretical study of mode instability in high-power fiber lasers by employing a universal model and its implications,” IEEE J. Sel. Top. Quantum Electron. 24, 1–19 (2018).
[Crossref]

Tünnermann, A.

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “The impact of pump-power noise on transverse mode instabilities,” Proc. SPIE 10897, 1089703 (2019).
[Crossref]

C. Stihler, H.-J. Otto, C. Jauregui, J. Limpert, and A. Tünnermann, “Experimental investigation of transverse mode instabilities in a double-pass yb-doped rod-type fiber amplifier,” Proc. SPIE 10083, 100830R (2017).
[Crossref]

H.-J. Otto, N. Modsching, C. Jauregui, J. Limpert, and A. Tünnermann, “Impact of photodarkening on the mode instability threshold,” Opt. Express 23, 15265–15277 (2015).
[Crossref]

C. Jauregui, H.-J. Otto, F. Stutzki, J. Limpert, and A. Tünnermann, “Simplified modelling the mode instability threshold of high power fiber amplifiers in the presence of photodarkening,” Opt. Express 23, 20203–20218 (2015).
[Crossref]

C. Jauregui, J. Limpert, and A. Tünnermann, “High-power fibre lasers,” Nat. Photonics 7, 861 (2013).
[Crossref]

C. Jauregui, T. Eidam, H.-J. Otto, F. Stutzki, F. Jansen, J. Limpert, and A. Tünnermann, “Physical origin of mode instabilities in high-power fiber laser systems,” Opt. Express 20, 12912–12925 (2012).
[Crossref]

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, 13218–13224 (2011).
[Crossref]

C. Jauregui, T. Eidam, J. Limpert, and A. Tünnermann, “Impact of modal interference on the beam quality of high-power fiber amplifiers,” Opt. Express 19, 3258–3271 (2011).
[Crossref]

T. Eidam, S. Hanf, E. Seise, T. V. Andersen, T. Gabler, C. Wirth, T. Schreiber, J. Limpert, and A. Tünnermann, “Femtosecond fiber CPA system emitting 830  W average output power,” Opt. Lett. 35, 94–96 (2010).
[Crossref]

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “Pump-power-noise influence on mode instabilities in high-power fiber laser systems,” in The European Conference on Lasers and Electro-Optics (Optical Society of America, 2019), paper cj_4_6.

Wang, X.

R. Tao, X. Wang, and P. Zhou, “Comprehensive theoretical study of mode instability in high-power fiber lasers by employing a universal model and its implications,” IEEE J. Sel. Top. Quantum Electron. 24, 1–19 (2018).
[Crossref]

Ward, B. G.

Wirth, C.

Zaouter, Y.

Zervas, M. N.

M. N. Zervas and C. A. Codemard, “High power fiber lasers: a review,” IEEE J. Sel. Top. Quantum Electron. 20, 219–241 (2014).
[Crossref]

Zhou, P.

R. Tao, X. Wang, and P. Zhou, “Comprehensive theoretical study of mode instability in high-power fiber lasers by employing a universal model and its implications,” IEEE J. Sel. Top. Quantum Electron. 24, 1–19 (2018).
[Crossref]

IEEE J. Sel. Top. Quantum Electron. (2)

M. N. Zervas and C. A. Codemard, “High power fiber lasers: a review,” IEEE J. Sel. Top. Quantum Electron. 20, 219–241 (2014).
[Crossref]

R. Tao, X. Wang, and P. Zhou, “Comprehensive theoretical study of mode instability in high-power fiber lasers by employing a universal model and its implications,” IEEE J. Sel. Top. Quantum Electron. 24, 1–19 (2018).
[Crossref]

J. Opt. Soc. Am. B (1)

Nat. Photonics (1)

C. Jauregui, J. Limpert, and A. Tünnermann, “High-power fibre lasers,” Nat. Photonics 7, 861 (2013).
[Crossref]

Opt. Express (14)

C. Jauregui, T. Eidam, J. Limpert, and A. Tünnermann, “Impact of modal interference on the beam quality of high-power fiber amplifiers,” Opt. Express 19, 3258–3271 (2011).
[Crossref]

T. T. Alkeskjold, M. Laurila, L. Scolari, and J. Broeng, “Single-mode ytterbium-doped large-mode-area photonic bandgap rod fiber amplifier,” Opt. Express 19, 7398–7409 (2011).
[Crossref]

A. V. Smith and J. J. Smith, “Mode instability in high power fiber amplifiers,” Opt. Express 19, 10180–10192 (2011).
[Crossref]

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, 13218–13224 (2011).
[Crossref]

C. Jauregui, T. Eidam, H.-J. Otto, F. Stutzki, F. Jansen, J. Limpert, and A. Tünnermann, “Physical origin of mode instabilities in high-power fiber laser systems,” Opt. Express 20, 12912–12925 (2012).
[Crossref]

K. R. Hansen, T. T. Alkeskjold, J. Broeng, and J. Lægsgaard, “Theoretical analysis of mode instability in high-power fiber amplifiers,” Opt. Express 21, 1944–1971 (2013).
[Crossref]

L. Dong, “Stimulated thermal Rayleigh scattering in optical fibers,” Opt. Express 21, 2642–2656 (2013).
[Crossref]

B. G. Ward, “Modeling of transient modal instability in fiber amplifiers,” Opt. Express 21, 12053–12067 (2013).
[Crossref]

A. V. Smith and J. J. Smith, “Increasing mode instability thresholds of fiber amplifiers by gain saturation,” Opt. Express 21, 15168–15182 (2013).
[Crossref]

M. M. Johansen, M. Laurila, M. D. Maack, D. Noordegraaf, C. Jakobsen, T. T. Alkeskjold, and J. Lægsgaard, “Frequency resolved transverse mode instability in rod fiber amplifiers,” Opt. Express 21, 21847–21856 (2013).
[Crossref]

K. R. Hansen and J. Lægsgaard, “Impact of gain saturation on the mode instability threshold in high-power fiber amplifiers,” Opt. Express 22, 11267–11278 (2014).
[Crossref]

H.-J. Otto, N. Modsching, C. Jauregui, J. Limpert, and A. Tünnermann, “Impact of photodarkening on the mode instability threshold,” Opt. Express 23, 15265–15277 (2015).
[Crossref]

C. Jauregui, H.-J. Otto, F. Stutzki, J. Limpert, and A. Tünnermann, “Simplified modelling the mode instability threshold of high power fiber amplifiers in the presence of photodarkening,” Opt. Express 23, 20203–20218 (2015).
[Crossref]

J. Lægsgaard, “Static thermo-optic instability in double-pass fiber amplifiers,” Opt. Express 24, 13429–13443 (2016).
[Crossref]

Opt. Lett. (4)

Proc. SPIE (2)

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “The impact of pump-power noise on transverse mode instabilities,” Proc. SPIE 10897, 1089703 (2019).
[Crossref]

C. Stihler, H.-J. Otto, C. Jauregui, J. Limpert, and A. Tünnermann, “Experimental investigation of transverse mode instabilities in a double-pass yb-doped rod-type fiber amplifier,” Proc. SPIE 10083, 100830R (2017).
[Crossref]

Other (1)

C. Stihler, C. Jauregui, A. Tünnermann, and J. Limpert, “Pump-power-noise influence on mode instabilities in high-power fiber laser systems,” in The European Conference on Lasers and Electro-Optics (Optical Society of America, 2019), paper cj_4_6.

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Figures (11)

Fig. 1.
Fig. 1. Experimental setup for dual-pass amplification. PBS, polarizing beam splitter; Dic, dichroic mirror.
Fig. 2.
Fig. 2. Main (blue solid circle) and discarded (red solid circle) powers as function of pump power at 10 mW input seed power.
Fig. 3.
Fig. 3. Power spectra for several pump powers and 10 mW seed.
Fig. 4.
Fig. 4. Selected images of the main and discarded outputs obtained from 10 mW seed. (a) Main output 18 W from 67 W pump. (b) Main output 72 W from 183 W pump. (c) Main output 112 W from 265 W pump. (d) Discarded output 110 mW from 67 W pump. (e) Discarded output 760 mW from 183 W pump. (f) Discarded output 3 W from 265 W pump. The white circle is a 90 µm aperture. All images have the same scale.
Fig. 5.
Fig. 5. Main power as function of pump power for various input powers. Maximum gain (Mg) is indicated for each seed power.
Fig. 6.
Fig. 6. Maximum power (blue solid circle) and gain (red solid circle) achievable as function of input power in lin–log scale. Dashed red line is logarithmic fit for maximum gain. Blacks dots: previous work [17].
Fig. 7.
Fig. 7. Discarded power as function of pump power for various input powers. Maximum gain (Mg) is indicated for each seed power.
Fig. 8.
Fig. 8. Higher-order mode fractions as function of pump power for all solutions identified with seed powers of 1 W (black circles), 100 mW (red squares), 30 mW (green diamonds), and 10 mW (blue triangles).
Fig. 9.
Fig. 9. Simulated ${{\rm LP}_{01}}$ signal power (black squares) and amplifier efficiency (red circles) at SMD threshold versus seed power.
Fig. 10.
Fig. 10. Power distribution of forward- and backward-propagating signal modes along the length of the rod. Top: 1 W seed, 48 W pump power. Bottom: 10 mW seed, 145 W pump power.
Fig. 11.
Fig. 11. Left: simulated quarter-structure of the aeroGAIN-ROD-PM85 amplifier. Small circles are airholes, larger circles are Ge-doped regions, and the hexagonal shape in the core region denotes the doped core. Right: intensity (color) and field (arrows) profiles of ${{\rm TE}_{01}}$, ${{\rm HE}_{21}}$, and ${{\rm TM}_{01}}$ modes in the core region.

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