Abstract

A straightforward method is presented for generating a stigmatic spherical thermal lens in laser-diode-pumped, Brewster-cut solid-state gain media by shaping the aspect ratio of the elliptical pumped region. Demonstration of this laser head design with Nd:GdVO4 as the gain medium yields a stable, efficient, high-power (>20W) diode-pumped laser at 1063nm. Analysis of the spatial mode characteristics of a 67cm-long symmetric resonator both confirms the radially symmetric nature of the pump-induced thermal lens and indicates that laser resonators incorporating this head design can readily generate a high spatial beam quality (M 2<2).

© 2004 Optical Society of America

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References

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  1. See, for example, R. Scheps, Introduction to laser diode-pumped solid state lasers, Tutorial Texts in Optical Engineering, vol. TT53 (International Society of Optical Engineering (SPIE), 2002).
  2. W. Koechner, Solid-State Laser Engineering, 4th edition (Springer-Verlag, Berlin, 1996).
  3. H. Zhang, J. Liu, J. Wang, C. Wang, L. Zhu, Z. Shao, X. Meng, X. Hu, M. Jiang, and Y.T. Chow, �??Characterization of the laser crystal Nd:GdVO4,�?? J. Opt. Soc. Am. B 19, 18-27 (2002).
    [CrossRef]
  4. Y.F. Chen, T.M. Huang, C.C. Liao, Y.P. Lan, and S.C. Wang, �??Efficient high-power diode-end-pumped TEM00 Nd:YVO4 laser�?? IEEE Photon. Technol. Lett. 11, 1241-1243 (1999).
    [CrossRef]
  5. J. Liu, Z. Shao, H. Zhang, X. Meng, L. Zhu, and M. Jiang, �??Diode-laser-array end-pumped 14.3W CW Nd:GdVO4 solid-state laser at 1.06µm,�?? Appl. Phys. B 69, 241-243 (1999).
    [CrossRef]
  6. Y.F. Chen, Y.P. Lan, and S.C. Wang, �??High-power diode-end-pumped Nd:YVO4 laser: thermally induced fracture versus pump-wavelength sensitivity,�?? Appl. Phys. B 71, 827-830 (2000).
    [CrossRef]
  7. A. Giesen, H. Hügel, A. Voss, K. Wittig, U. Brauch, and H. Opower, �??Scalable concept for diode-pumped high-power solid-state-lasers,�?? Appl. Phys. B 58, 365-372 (1994).
    [CrossRef]
  8. B.A. Thompson, A. Minassian, and M.J. Damzen, �??Operation of a 33-W, continuous-wave, self-adaptive, solid-state laser oscillator,�?? J. Opt. Soc. Am. B 20, 857-862 (2003).
    [CrossRef]
  9. J.E. Bernard and A.J. Alcock, �??High-efficiency diode-pumped Nd:YVO4 slab laser,�?? Opt. Lett. 18, 968-970 (1993).
    [CrossRef] [PubMed]
  10. C. Stewen, K. Contag, M. Larionov, A. Giesen, and H. Hügel, �??A 1-kW CW thin disc laser,�?? IEEE J. Sel. Top. Quantum. Electron. 6, 650-657 (2000).
    [CrossRef]
  11. Product information on Yb:YAG thin disk laser (Electronik Laser Systems GmbH, 2004), <a href= "http://www.versadisk.com/Products/vdisk.html"> http://www.versadisk.com/Products/vdisk.html</a>.
  12. S. Knoke, G. Hollemann, M. Nickel, and H. Voelckel, �??Frequency doubled Nd:YVO4 thin disk laser with 30% diode-to-green efficiency,�?? paper CThC2 in Technical Digest of the Conference on Lasers and Electro-Optics 2001 (Baltimore, MD), (Optical Society of America, Washington DC, 2001) p.388-389.
  13. H.W. Kogelnik, E.P. Ippen, A. Dienes, and C.V. Shank, �??Astigmatically compensated cavities for CW dye lasers,�?? IEEE J. Quantum. Electron. QE-8, 373-379 (1972).
    [CrossRef]
  14. M. Mehendale, T.R. Nelson, F.G. Omenetto, and W.A. Schroeder, �??Thermal effects in laser pumped Kerr-lens modelocked Ti:sapphire lasers,�?? Opt. Commun. 136, 150-159 (1997).
    [CrossRef]
  15. A.E. Siegman, Lasers (University Science Books, Sausalito, CA, 1986).
  16. L. Xu, G. Tempea, A. Poppe, M. Lenzner, Ch. Spielmann, F. Krausz, A. Stingl, and K. Ferencz, �??High-power sub-10-fs Ti:sapphire oscillators,�?? Appl. Phys. B 65, 151-159 (1997).
    [CrossRef]
  17. R. Paschotta, J. Aus der Au, G.J. Spühler, F. Morier-Genoud, R. Hövel, M. Moser, S. Erhard, M. Karszewski, A. Giesen, and U. Keller, �??Diode-pumped passively mode-locked lasers with high average power,�?? Appl. Phys. B 70, S25-S31 (2000).
    [CrossRef]
  18. Artic Silver 5, High-density Polysynthetic Silver Thermal Compound (Artic Silver, 2004), <a href= "http://www.articsilver.com/as5.htm"> http://www.articsilver.com/as5.htm</a>.
  19. T. Jensen, V.G. Ostroumov, J.-P. Meyn, G. Huber, A.I. Zagumennyi, I.A. Shcherbakov, �??Spectroscopic characterization and laser performance of diode-laser-pumped Nd:GdVO4,�?? Appl. Phys. B 58, 373-379 (1994).
    [CrossRef]
  20. Q. Fu, F. Seier, S.K. Gayen, and R.R. Alfano,�??High-average-power kilohertz-repetition-rate sub-100-fs Ti:sapphire amplifier system,�?? Opt. Lett. 22, 712-714 (1997).
    [CrossRef] [PubMed]
  21. P.A. Studenikin, A.I. Zagumennyi, Yu.D. Zavaratsev, P.A. Popov, and I.A. Shcherbakov, �??GdVO4 as a new medium for solid-state lasers: some optical and thermal properties of crystals doped with Nd3+, Tm3+, and Er3+ ions,�?? Quantum Electron. 25, 1162-1165 (1995).
    [CrossRef]
  22. P.K. Mukhopadhyay, A. Nautiyal, P.K. Gupta, K. Ranganathan, J. George, S.K. Sharma, and T.P.S. Nathan, �??Experimental determination of the thermo-optic coefficient (dn/dT) and the effective stimulated emission cross-section (�?e) of an a-axis cut 1.-at. % doped Nd:GdVO4 crystal at 1.06µm wavelength,�?? Appl. Phys. B 77, 81-87 (2003).
    [CrossRef]
  23. 808nm 40W CW laser diode array (Northrup Grumman Space Technologies, Cutting Edge Optronics, 2004), <a href= "http://www.imclaser.com/pdf/808-CS-40W-single.pdf"> http://www.imclaser.com/pdf/808-CS-40W-single.pdf</a>.
  24. N. Hodgson and H. Weber, Optical Resonators (Springer, Berlin-Heidelberg, 1997).
  25. W.A. Clarkson, �??Thermal effects and their mitigation in end-pumped solid-state lasers,�?? J. Phys. D: Appl. Phys. 34, 2381-2395 (2001).
    [CrossRef]

Appl. Phys. B

L. Xu, G. Tempea, A. Poppe, M. Lenzner, Ch. Spielmann, F. Krausz, A. Stingl, and K. Ferencz, �??High-power sub-10-fs Ti:sapphire oscillators,�?? Appl. Phys. B 65, 151-159 (1997).
[CrossRef]

R. Paschotta, J. Aus der Au, G.J. Spühler, F. Morier-Genoud, R. Hövel, M. Moser, S. Erhard, M. Karszewski, A. Giesen, and U. Keller, �??Diode-pumped passively mode-locked lasers with high average power,�?? Appl. Phys. B 70, S25-S31 (2000).
[CrossRef]

J. Liu, Z. Shao, H. Zhang, X. Meng, L. Zhu, and M. Jiang, �??Diode-laser-array end-pumped 14.3W CW Nd:GdVO4 solid-state laser at 1.06µm,�?? Appl. Phys. B 69, 241-243 (1999).
[CrossRef]

Y.F. Chen, Y.P. Lan, and S.C. Wang, �??High-power diode-end-pumped Nd:YVO4 laser: thermally induced fracture versus pump-wavelength sensitivity,�?? Appl. Phys. B 71, 827-830 (2000).
[CrossRef]

A. Giesen, H. Hügel, A. Voss, K. Wittig, U. Brauch, and H. Opower, �??Scalable concept for diode-pumped high-power solid-state-lasers,�?? Appl. Phys. B 58, 365-372 (1994).
[CrossRef]

T. Jensen, V.G. Ostroumov, J.-P. Meyn, G. Huber, A.I. Zagumennyi, I.A. Shcherbakov, �??Spectroscopic characterization and laser performance of diode-laser-pumped Nd:GdVO4,�?? Appl. Phys. B 58, 373-379 (1994).
[CrossRef]

P.K. Mukhopadhyay, A. Nautiyal, P.K. Gupta, K. Ranganathan, J. George, S.K. Sharma, and T.P.S. Nathan, �??Experimental determination of the thermo-optic coefficient (dn/dT) and the effective stimulated emission cross-section (�?e) of an a-axis cut 1.-at. % doped Nd:GdVO4 crystal at 1.06µm wavelength,�?? Appl. Phys. B 77, 81-87 (2003).
[CrossRef]

CLEO 2001

S. Knoke, G. Hollemann, M. Nickel, and H. Voelckel, �??Frequency doubled Nd:YVO4 thin disk laser with 30% diode-to-green efficiency,�?? paper CThC2 in Technical Digest of the Conference on Lasers and Electro-Optics 2001 (Baltimore, MD), (Optical Society of America, Washington DC, 2001) p.388-389.

IEEE J. Quantum. Electron.

H.W. Kogelnik, E.P. Ippen, A. Dienes, and C.V. Shank, �??Astigmatically compensated cavities for CW dye lasers,�?? IEEE J. Quantum. Electron. QE-8, 373-379 (1972).
[CrossRef]

IEEE J. Sel. Top. Quantum. Electron.

C. Stewen, K. Contag, M. Larionov, A. Giesen, and H. Hügel, �??A 1-kW CW thin disc laser,�?? IEEE J. Sel. Top. Quantum. Electron. 6, 650-657 (2000).
[CrossRef]

IEEE Photon. Technol. Lett.

Y.F. Chen, T.M. Huang, C.C. Liao, Y.P. Lan, and S.C. Wang, �??Efficient high-power diode-end-pumped TEM00 Nd:YVO4 laser�?? IEEE Photon. Technol. Lett. 11, 1241-1243 (1999).
[CrossRef]

J. Opt. Soc. Am. B

J. Phys. D: Appl. Phys.

W.A. Clarkson, �??Thermal effects and their mitigation in end-pumped solid-state lasers,�?? J. Phys. D: Appl. Phys. 34, 2381-2395 (2001).
[CrossRef]

Opt. Commun.

M. Mehendale, T.R. Nelson, F.G. Omenetto, and W.A. Schroeder, �??Thermal effects in laser pumped Kerr-lens modelocked Ti:sapphire lasers,�?? Opt. Commun. 136, 150-159 (1997).
[CrossRef]

Opt. Lett.

Quantum Electron.

P.A. Studenikin, A.I. Zagumennyi, Yu.D. Zavaratsev, P.A. Popov, and I.A. Shcherbakov, �??GdVO4 as a new medium for solid-state lasers: some optical and thermal properties of crystals doped with Nd3+, Tm3+, and Er3+ ions,�?? Quantum Electron. 25, 1162-1165 (1995).
[CrossRef]

Tutorial Texts in Optical Engineering

See, for example, R. Scheps, Introduction to laser diode-pumped solid state lasers, Tutorial Texts in Optical Engineering, vol. TT53 (International Society of Optical Engineering (SPIE), 2002).

Other

W. Koechner, Solid-State Laser Engineering, 4th edition (Springer-Verlag, Berlin, 1996).

808nm 40W CW laser diode array (Northrup Grumman Space Technologies, Cutting Edge Optronics, 2004), <a href= "http://www.imclaser.com/pdf/808-CS-40W-single.pdf"> http://www.imclaser.com/pdf/808-CS-40W-single.pdf</a>.

N. Hodgson and H. Weber, Optical Resonators (Springer, Berlin-Heidelberg, 1997).

A.E. Siegman, Lasers (University Science Books, Sausalito, CA, 1986).

Product information on Yb:YAG thin disk laser (Electronik Laser Systems GmbH, 2004), <a href= "http://www.versadisk.com/Products/vdisk.html"> http://www.versadisk.com/Products/vdisk.html</a>.

Artic Silver 5, High-density Polysynthetic Silver Thermal Compound (Artic Silver, 2004), <a href= "http://www.articsilver.com/as5.htm"> http://www.articsilver.com/as5.htm</a>.

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Figures (6)

Fig. 1.
Fig. 1.

Thermal lens effects in the sagittal and tangential planes of a symmetrically longitudinally pumped, Brewster-cut solid-state laser gain medium of length l; shown are the bulk GRIN lens (shaded) generated by absorption absorption of pump radiation and heat conduction and the surface bowing with radii Rx and Ry due to thermal expansion near the crystal face. The employed coordinate system is also defined; x is the tangential direction, y is the sagittal direction, and z is the longitudinal (or propagation) direction.

Fig. 2.
Fig. 2.

Schematic of the diode-pumped Nd:GdVO4 laser head design: 40W, 808nm laser diode arrays (LD); f=20mm spherical lens (L1); f=10mm cylindrical lens (L2); 808nm half-wave plate (HWP).

Fig. 3.
Fig. 3.

Pump radiation ray tracing through the pump optics (L1 and L2) from one LD array into the 3×5×10 mm Nd:GdVO4 gain medium; (a) for 5 of the 46 emitters across the 1cm width of the LD bar in the tangential plane and (b) for the central LD bar emitter in the sagittal plane. For each depicted emitter five rays are shown; the central ray, two rays at half the 1/e2 irradiance divergence angle, and the two extreme rays at the 1/e2 irradiance divergence angle (±5° in the tangential plane and ±20° fast-axis divergence in the sagittal plane).

Fig. 4.
Fig. 4.

Symmetric laser cavity output powers as a function of LD pump power (drive current) for six symmetric laser cavity lengths between 32 and 84cm. The solid black line indicates the confocal resonator condition that separates cavity stability regions I and II (shaded).

Fig. 5.
Fig. 5.

The measured tangential (x) and sagittal (y) spatial mode characteristics of the 67cm-long symmetric laser cavity as a function of LD drive current; the embedded TEM00 mode radius w 0 at the 8% output coupler (black) and the M 2 beam quality in the x and y directions (red).

Fig. 6.
Fig. 6.

The power of the pump-induced thermal lens in the Brewster-cut Nd:GdVO4 gain medium evaluated as a function of LD drive current for both the tangential (x) and sagittal (y) directions.

Equations (5)

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T ( x , y ) = T 0 1 2 ( A T x 2 + B T y 2 ) .
( A B C D ) x = ( 1 Δ x l n 2 R x l n 3 Δ x 2 l n R x 2 [ n 2 γ x 2 l + 2 n Δ x R x ] 1 Δ x l n 2 R x ) ,
( A B C D ) y = ( 1 Δ y l n R y l n Δ y 2 l n R y 2 [ γ y 2 l + 2 Δ y R y ] 1 Δ y l n R y ) .
Δ y = n sin θ B cos θ B and Δ x = Δ y sin θ B cos θ B ,
B T { ( dn dT ) l + 2 Δ y α T d } A T { n 2 ( dn dT ) l + 2 n Δ x α T d } .

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