Abstract

In this paper we introduce a simple scheme to spectrally combine four single beams using three low-cost dielectric interference filters as combining elements. 25 ns pulses from four independent and actively Q-switched fiber seed-sources are amplified in a single stage fiber-amplifier. Temporally and spatially combined 208 W of average power and 6.3 mJ of pulse energy are obtained at two different repetition frequencies. A detailed analysis of beam quality as well as the thermal behavior of the combining elements is carried out and reveals mutual dependency.

©2009 Optical Society of America

Full Article  |  PDF Article
OSA Recommended Articles
10 kW-level spectral beam combination of two high power broad-linewidth fiber lasers by means of edge filters

Fan Chen, Jun Ma, Cong Wei, Rihong Zhu, Wenchao Zhou, Qun Yuan, Shaohua Pan, JianYun Zhang, Yize Wen, and Jiantai Dou
Opt. Express 25(26) 32783-32791 (2017)

Coupling efficiency model for spectral beam combining of high-power fiber lasers calculated from spectrum

Fan Chen, Jun Ma, Rihong Zhu, Qun Yuan, Wenchao Zhou, Junhong Su, Junqi Xu, and Shaohua Pan
Appl. Opt. 56(10) 2574-2579 (2017)

187 W, 3.7 mJ from spectrally combined pulsed 2 ns fiber amplifiers

O. Schmidt, T. V. Andersen, J. Limpert, and A. Tünnermann
Opt. Lett. 34(3) 226-228 (2009)

More Recommended Articles

References

  • View by:
  • Article Order
  • |
  • Year
  • |
  • Author
  • |
  • Publication
  1. J. Limpert, A. Liem, H. Zellmer, and A. Tünnermann, “500 W continuous-wave fiber laser with excellent beam quality,” Electron. Lett. 39(8), 645 ( 2003).
    [Crossref]
  2. Y. Jeong, J. Sahu, D. Payne, and J. Nilsson, “Ytterbium-doped large-core fiber laser with 1.36 kW continuous-wave output power,” Opt. Express 12(25), 6088–6092 ( 2004), http://www.opticsinfobase.org/abstract.cfm?URI=oe-12-25-6088 .
    [Crossref] [PubMed]
  3. D. Gapontsev, and I. P. G. Photonics, “6kW CW Single Mode Ytterbium Fiber Laser in All-Fiber Format,” in “Solid State and Diode Laser Technology Review” Albuquerque (2008).
  4. J. W. Dawson, M. J. Messerly, R. J. Beach, M. Y. Shverdin, E. A. Stappaerts, A. K. Sridharan, P. H. Pax, J. E. Heebner, C. W. Siders, and C. P. J. Barty, “Analysis of the scalability of diffraction-limited fiber lasers and amplifiers to high average power,” Opt. Express 16(17), 13240–13266 ( 2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-17-13240 .
    [Crossref] [PubMed]
  5. F. Röser, D. Schimpf, J. Rothhardt, T. Eidam, J. Limpert, A. Tünnermann and F. Salin, ”Gain Limitations and Consequences for Short Length Fiber Amplifiers,” in Advanced Solid-State Photonics (Optical Society of America, Nara, 2007), paper WB22.
  6. J. Limpert, O. Schmidt, J. Rothhardt, F. Röser, T. Schreiber, A. Tünnermann, S. Ermeneux, P. Yvernault, and F. Salin, “Extended single-mode photonic crystal fiber lasers,” Opt. Express 14(7), 2715–2720 ( 2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-7-2715 .
    [Crossref] [PubMed]
  7. C. D. Brooks and F. Di Teodoro, “Multimegawatt peak-power, single-transverse-mode operation of a 100µm core diameter, Yb-doped rodlike photonic crystal fiber amplifier,” Appl. Phys. Lett. 89(11), 111119–111122 ( 2006).
    [Crossref]
  8. O. Schmidt, J. Rothhardt, T. Eidam, F. Röser, J. Limpert, A. Tünnermann, K. P. Hansen, C. Jakobsen, and J. Broeng, “Single-polarization ultra-large-mode-area Yb-doped photonic crystal fiber,” Opt. Express 16(6), 3918–3923 ( 2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-6-3918 .
    [Crossref] [PubMed]
  9. F. Röser, T. Eidam, J. Rothhardt, O. Schmidt, D. N. Schimpf, J. Limpert, and A. Tünnermann, “Millijoule pulse energy high repetition rate femtosecond fiber chirped-pulse amplification system,” Opt. Lett. 32(24), 3495–3497 ( 2007), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-32-24-3495 .
    [Crossref] [PubMed]
  10. L. Dong, H. A. McKay, L. Fu, M. Ohta, A. Marcinkevicius, S. Suzuki, and M. E. Fermann, “Ytterbium-doped all glass leakage channel fibers with highly fluorine-doped silica pump cladding,” Opt. Express 17(11), 8962–8969 ( 2009), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-11-8962 .
    [Crossref] [PubMed]
  11. A. Sevian, O. Andrusyak, I. Ciapurin, V. Smirnov, G. Venus, and L. Glebov, “Efficient power scaling of laser radiation by spectral beam combining,” Opt. Lett. 33(4), 384–386 ( 2008), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-33-4-384 .
    [Crossref] [PubMed]
  12. C. Wirth, O. Schmidt, I. Tsybin, T. Schreiber, T. Peschel, F. Brückner, T. Clausnitzer, J. Limpert, R. Eberhardt, A. Tünnermann, M. Gowin, E. ten Have, K. Ludewigt, and M. Jung, “2 kW incoherent beam combining of four narrow-linewidth photonic crystal fiber amplifiers,” Opt. Express 17(3), 1178–1183 ( 2009), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-3-1178 .
    [Crossref] [PubMed]
  13. O. Schmidt, T. V. Andersen, J. Limpert, and A. Tünnermann, “187 W, 3.7 mJ from spectrally combined pulsed 2 ns fiber amplifiers,” Opt. Lett. 34(3), 226–228 ( 2009), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-34-3-226 .
    [Crossref] [PubMed]
  14. O. Schmidt, C. Wirth, I. Tsybin, T. Schreiber, R. Eberhardt, J. Limpert, and A. Tünnermann, “Average power of 1.1 kW from spectrally combined, fiber-amplified, nanosecond-pulsed sources,” Opt. Lett. 34(10), 1567–1569 ( 2009), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-34-10-1567 .
    [Crossref] [PubMed]
  15. K. Regelskis, K. Hou, G. Raciukaitis, and A. Galvanauskas, “Spatial-Dispersion-Free Spectral Beam Combining of High Power Pulsed Yb-Doped Fiber Lasers,” in Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies, OSA Technical Digest (CD) (Optical Society of America, 2008), paper CMA4.
  16. Semrock: MaxLine Common Specifications, http://www.semrock.com/catalog/MaxLine_CommonSpecs .

2009 (4)

2008 (3)

2007 (1)

2006 (2)

J. Limpert, O. Schmidt, J. Rothhardt, F. Röser, T. Schreiber, A. Tünnermann, S. Ermeneux, P. Yvernault, and F. Salin, “Extended single-mode photonic crystal fiber lasers,” Opt. Express 14(7), 2715–2720 ( 2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-7-2715 .
[Crossref] [PubMed]

C. D. Brooks and F. Di Teodoro, “Multimegawatt peak-power, single-transverse-mode operation of a 100µm core diameter, Yb-doped rodlike photonic crystal fiber amplifier,” Appl. Phys. Lett. 89(11), 111119–111122 ( 2006).
[Crossref]

2004 (1)

2003 (1)

J. Limpert, A. Liem, H. Zellmer, and A. Tünnermann, “500 W continuous-wave fiber laser with excellent beam quality,” Electron. Lett. 39(8), 645 ( 2003).
[Crossref]

Andersen, T. V.

Andrusyak, O.

Barty, C. P. J.

Beach, R. J.

Broeng, J.

Brooks, C. D.

C. D. Brooks and F. Di Teodoro, “Multimegawatt peak-power, single-transverse-mode operation of a 100µm core diameter, Yb-doped rodlike photonic crystal fiber amplifier,” Appl. Phys. Lett. 89(11), 111119–111122 ( 2006).
[Crossref]

Brückner, F.

Ciapurin, I.

Clausnitzer, T.

Dawson, J. W.

Di Teodoro, F.

C. D. Brooks and F. Di Teodoro, “Multimegawatt peak-power, single-transverse-mode operation of a 100µm core diameter, Yb-doped rodlike photonic crystal fiber amplifier,” Appl. Phys. Lett. 89(11), 111119–111122 ( 2006).
[Crossref]

Dong, L.

Eberhardt, R.

Eidam, T.

Ermeneux, S.

Fermann, M. E.

Fu, L.

Glebov, L.

Gowin, M.

Hansen, K. P.

Heebner, J. E.

Jakobsen, C.

Jeong, Y.

Jung, M.

Liem, A.

J. Limpert, A. Liem, H. Zellmer, and A. Tünnermann, “500 W continuous-wave fiber laser with excellent beam quality,” Electron. Lett. 39(8), 645 ( 2003).
[Crossref]

Limpert, J.

C. Wirth, O. Schmidt, I. Tsybin, T. Schreiber, T. Peschel, F. Brückner, T. Clausnitzer, J. Limpert, R. Eberhardt, A. Tünnermann, M. Gowin, E. ten Have, K. Ludewigt, and M. Jung, “2 kW incoherent beam combining of four narrow-linewidth photonic crystal fiber amplifiers,” Opt. Express 17(3), 1178–1183 ( 2009), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-3-1178 .
[Crossref] [PubMed]

O. Schmidt, T. V. Andersen, J. Limpert, and A. Tünnermann, “187 W, 3.7 mJ from spectrally combined pulsed 2 ns fiber amplifiers,” Opt. Lett. 34(3), 226–228 ( 2009), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-34-3-226 .
[Crossref] [PubMed]

O. Schmidt, C. Wirth, I. Tsybin, T. Schreiber, R. Eberhardt, J. Limpert, and A. Tünnermann, “Average power of 1.1 kW from spectrally combined, fiber-amplified, nanosecond-pulsed sources,” Opt. Lett. 34(10), 1567–1569 ( 2009), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-34-10-1567 .
[Crossref] [PubMed]

O. Schmidt, J. Rothhardt, T. Eidam, F. Röser, J. Limpert, A. Tünnermann, K. P. Hansen, C. Jakobsen, and J. Broeng, “Single-polarization ultra-large-mode-area Yb-doped photonic crystal fiber,” Opt. Express 16(6), 3918–3923 ( 2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-6-3918 .
[Crossref] [PubMed]

F. Röser, T. Eidam, J. Rothhardt, O. Schmidt, D. N. Schimpf, J. Limpert, and A. Tünnermann, “Millijoule pulse energy high repetition rate femtosecond fiber chirped-pulse amplification system,” Opt. Lett. 32(24), 3495–3497 ( 2007), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-32-24-3495 .
[Crossref] [PubMed]

J. Limpert, O. Schmidt, J. Rothhardt, F. Röser, T. Schreiber, A. Tünnermann, S. Ermeneux, P. Yvernault, and F. Salin, “Extended single-mode photonic crystal fiber lasers,” Opt. Express 14(7), 2715–2720 ( 2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-7-2715 .
[Crossref] [PubMed]

J. Limpert, A. Liem, H. Zellmer, and A. Tünnermann, “500 W continuous-wave fiber laser with excellent beam quality,” Electron. Lett. 39(8), 645 ( 2003).
[Crossref]

Ludewigt, K.

Marcinkevicius, A.

McKay, H. A.

Messerly, M. J.

Nilsson, J.

Ohta, M.

Pax, P. H.

Payne, D.

Peschel, T.

Röser, F.

Rothhardt, J.

Sahu, J.

Salin, F.

Schimpf, D. N.

Schmidt, O.

O. Schmidt, T. V. Andersen, J. Limpert, and A. Tünnermann, “187 W, 3.7 mJ from spectrally combined pulsed 2 ns fiber amplifiers,” Opt. Lett. 34(3), 226–228 ( 2009), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-34-3-226 .
[Crossref] [PubMed]

C. Wirth, O. Schmidt, I. Tsybin, T. Schreiber, T. Peschel, F. Brückner, T. Clausnitzer, J. Limpert, R. Eberhardt, A. Tünnermann, M. Gowin, E. ten Have, K. Ludewigt, and M. Jung, “2 kW incoherent beam combining of four narrow-linewidth photonic crystal fiber amplifiers,” Opt. Express 17(3), 1178–1183 ( 2009), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-3-1178 .
[Crossref] [PubMed]

O. Schmidt, C. Wirth, I. Tsybin, T. Schreiber, R. Eberhardt, J. Limpert, and A. Tünnermann, “Average power of 1.1 kW from spectrally combined, fiber-amplified, nanosecond-pulsed sources,” Opt. Lett. 34(10), 1567–1569 ( 2009), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-34-10-1567 .
[Crossref] [PubMed]

O. Schmidt, J. Rothhardt, T. Eidam, F. Röser, J. Limpert, A. Tünnermann, K. P. Hansen, C. Jakobsen, and J. Broeng, “Single-polarization ultra-large-mode-area Yb-doped photonic crystal fiber,” Opt. Express 16(6), 3918–3923 ( 2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-6-3918 .
[Crossref] [PubMed]

F. Röser, T. Eidam, J. Rothhardt, O. Schmidt, D. N. Schimpf, J. Limpert, and A. Tünnermann, “Millijoule pulse energy high repetition rate femtosecond fiber chirped-pulse amplification system,” Opt. Lett. 32(24), 3495–3497 ( 2007), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-32-24-3495 .
[Crossref] [PubMed]

J. Limpert, O. Schmidt, J. Rothhardt, F. Röser, T. Schreiber, A. Tünnermann, S. Ermeneux, P. Yvernault, and F. Salin, “Extended single-mode photonic crystal fiber lasers,” Opt. Express 14(7), 2715–2720 ( 2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-7-2715 .
[Crossref] [PubMed]

Schreiber, T.

Sevian, A.

Shverdin, M. Y.

Siders, C. W.

Smirnov, V.

Sridharan, A. K.

Stappaerts, E. A.

Suzuki, S.

ten Have, E.

Tsybin, I.

Tünnermann, A.

O. Schmidt, C. Wirth, I. Tsybin, T. Schreiber, R. Eberhardt, J. Limpert, and A. Tünnermann, “Average power of 1.1 kW from spectrally combined, fiber-amplified, nanosecond-pulsed sources,” Opt. Lett. 34(10), 1567–1569 ( 2009), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-34-10-1567 .
[Crossref] [PubMed]

O. Schmidt, T. V. Andersen, J. Limpert, and A. Tünnermann, “187 W, 3.7 mJ from spectrally combined pulsed 2 ns fiber amplifiers,” Opt. Lett. 34(3), 226–228 ( 2009), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-34-3-226 .
[Crossref] [PubMed]

C. Wirth, O. Schmidt, I. Tsybin, T. Schreiber, T. Peschel, F. Brückner, T. Clausnitzer, J. Limpert, R. Eberhardt, A. Tünnermann, M. Gowin, E. ten Have, K. Ludewigt, and M. Jung, “2 kW incoherent beam combining of four narrow-linewidth photonic crystal fiber amplifiers,” Opt. Express 17(3), 1178–1183 ( 2009), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-3-1178 .
[Crossref] [PubMed]

O. Schmidt, J. Rothhardt, T. Eidam, F. Röser, J. Limpert, A. Tünnermann, K. P. Hansen, C. Jakobsen, and J. Broeng, “Single-polarization ultra-large-mode-area Yb-doped photonic crystal fiber,” Opt. Express 16(6), 3918–3923 ( 2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-6-3918 .
[Crossref] [PubMed]

F. Röser, T. Eidam, J. Rothhardt, O. Schmidt, D. N. Schimpf, J. Limpert, and A. Tünnermann, “Millijoule pulse energy high repetition rate femtosecond fiber chirped-pulse amplification system,” Opt. Lett. 32(24), 3495–3497 ( 2007), http://www.opticsinfobase.org/ol/abstract.cfm?URI=ol-32-24-3495 .
[Crossref] [PubMed]

J. Limpert, O. Schmidt, J. Rothhardt, F. Röser, T. Schreiber, A. Tünnermann, S. Ermeneux, P. Yvernault, and F. Salin, “Extended single-mode photonic crystal fiber lasers,” Opt. Express 14(7), 2715–2720 ( 2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-7-2715 .
[Crossref] [PubMed]

J. Limpert, A. Liem, H. Zellmer, and A. Tünnermann, “500 W continuous-wave fiber laser with excellent beam quality,” Electron. Lett. 39(8), 645 ( 2003).
[Crossref]

Venus, G.

Wirth, C.

Yvernault, P.

Zellmer, H.

J. Limpert, A. Liem, H. Zellmer, and A. Tünnermann, “500 W continuous-wave fiber laser with excellent beam quality,” Electron. Lett. 39(8), 645 ( 2003).
[Crossref]

Appl. Phys. Lett. (1)

C. D. Brooks and F. Di Teodoro, “Multimegawatt peak-power, single-transverse-mode operation of a 100µm core diameter, Yb-doped rodlike photonic crystal fiber amplifier,” Appl. Phys. Lett. 89(11), 111119–111122 ( 2006).
[Crossref]

Electron. Lett. (1)

J. Limpert, A. Liem, H. Zellmer, and A. Tünnermann, “500 W continuous-wave fiber laser with excellent beam quality,” Electron. Lett. 39(8), 645 ( 2003).
[Crossref]

Opt. Express (6)

Y. Jeong, J. Sahu, D. Payne, and J. Nilsson, “Ytterbium-doped large-core fiber laser with 1.36 kW continuous-wave output power,” Opt. Express 12(25), 6088–6092 ( 2004), http://www.opticsinfobase.org/abstract.cfm?URI=oe-12-25-6088 .
[Crossref] [PubMed]

J. W. Dawson, M. J. Messerly, R. J. Beach, M. Y. Shverdin, E. A. Stappaerts, A. K. Sridharan, P. H. Pax, J. E. Heebner, C. W. Siders, and C. P. J. Barty, “Analysis of the scalability of diffraction-limited fiber lasers and amplifiers to high average power,” Opt. Express 16(17), 13240–13266 ( 2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-17-13240 .
[Crossref] [PubMed]

O. Schmidt, J. Rothhardt, T. Eidam, F. Röser, J. Limpert, A. Tünnermann, K. P. Hansen, C. Jakobsen, and J. Broeng, “Single-polarization ultra-large-mode-area Yb-doped photonic crystal fiber,” Opt. Express 16(6), 3918–3923 ( 2008), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-16-6-3918 .
[Crossref] [PubMed]

L. Dong, H. A. McKay, L. Fu, M. Ohta, A. Marcinkevicius, S. Suzuki, and M. E. Fermann, “Ytterbium-doped all glass leakage channel fibers with highly fluorine-doped silica pump cladding,” Opt. Express 17(11), 8962–8969 ( 2009), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-11-8962 .
[Crossref] [PubMed]

C. Wirth, O. Schmidt, I. Tsybin, T. Schreiber, T. Peschel, F. Brückner, T. Clausnitzer, J. Limpert, R. Eberhardt, A. Tünnermann, M. Gowin, E. ten Have, K. Ludewigt, and M. Jung, “2 kW incoherent beam combining of four narrow-linewidth photonic crystal fiber amplifiers,” Opt. Express 17(3), 1178–1183 ( 2009), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-17-3-1178 .
[Crossref] [PubMed]

J. Limpert, O. Schmidt, J. Rothhardt, F. Röser, T. Schreiber, A. Tünnermann, S. Ermeneux, P. Yvernault, and F. Salin, “Extended single-mode photonic crystal fiber lasers,” Opt. Express 14(7), 2715–2720 ( 2006), http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-14-7-2715 .
[Crossref] [PubMed]

Opt. Lett. (4)

Other (4)

F. Röser, D. Schimpf, J. Rothhardt, T. Eidam, J. Limpert, A. Tünnermann and F. Salin, ”Gain Limitations and Consequences for Short Length Fiber Amplifiers,” in Advanced Solid-State Photonics (Optical Society of America, Nara, 2007), paper WB22.

D. Gapontsev, and I. P. G. Photonics, “6kW CW Single Mode Ytterbium Fiber Laser in All-Fiber Format,” in “Solid State and Diode Laser Technology Review” Albuquerque (2008).

K. Regelskis, K. Hou, G. Raciukaitis, and A. Galvanauskas, “Spatial-Dispersion-Free Spectral Beam Combining of High Power Pulsed Yb-Doped Fiber Lasers,” in Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference and Photonic Applications Systems Technologies, OSA Technical Digest (CD) (Optical Society of America, 2008), paper CMA4.

Semrock: MaxLine Common Specifications, http://www.semrock.com/catalog/MaxLine_CommonSpecs .

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (8)

Fig. 1
Fig. 1 Experimental setup of one of the four identical single laser systems consisting of a Q-switched fiber oscillator and a single-stage fiber amplifier.

Download Full Size | PPT Slide | PDF

Fig. 2
Fig. 2 (a) The combining stage is build up with three interference filters and combines four beams (B1-B4). Each IF can be tuned to the wavelengths, which are involved in the combining process. (b) The transmission curve of the IF shows 3 nm of spectral bandwidth and steep edges [16].

Download Full Size | PPT Slide | PDF

Fig. 3
Fig. 3 Once the pulses are temporally superposed pulse energy and pulse peak power are multiplied by a factor of four. The inset shows the measured spectrum of the combined beam.

Download Full Size | PPT Slide | PDF

Fig. 4
Fig. 4 Left scale: the amplifier slope of the combined beam has an efficiency of ~30% and reveals almost no roll-over effect. Right scale: the temperature of the IF12-34 is rising with higher output power and is increasing the beam quality factor M2 up to 2.3. The inset shows an image of the energy distribution in focus position of the combined beam at Pout = 208 W.

Download Full Size | PPT Slide | PDF

Fig. 5
Fig. 5 The measured pulse energy of the combined output beam is rising up to 6.3 mJ and is limited by gain saturation.

Download Full Size | PPT Slide | PDF

Fig. 6
Fig. 6 (a) The proposed setup is optimized for implementation of higher numbers of individual beams. Merely one beam is transmitted through each interference filter, which minimizes thermal lensing. (b) Setup of the ‘pump and probe’ experiment. The transmitted ‘pump’ beam is causing a thermal lens, which partly influences the wave-front of the reflected ‘probe’ beam.

Download Full Size | PPT Slide | PDF

Fig. 7
Fig. 7 Experimental data illustrate the decline of beam quality and the shift of focus position of the ‘probe’ beam as a function of the transmitted ‘pump’ power up to ~350 W.

Download Full Size | PPT Slide | PDF

Fig. 8
Fig. 8 Three measured transversal beam profiles at different positions of the caustic (which is shown schematically for illustration purpose). (a) The red circle marks the interaction zone of the thermal lens. The second focus is caused by the presence of this thermal lens (c).

Download Full Size | PPT Slide | PDF

Metrics