Abstract

A beam-shaping technique is presented for asymmetrical laser beams with different beam waists and divergences in both vertical and horizontal directions. We utilize a pair of two-dimensional micrograting arrays to equalize the beam parameter products of an asymmetrical beam in orthogonal directions by deflecting the appointed parts of the beam on the longer side of the beam and by recombining the parts on the shorter side. When combined with divergent transformation by means of collimating optical components, the beam-shaping system can produce a symmetrical beam in orthogonal directions with optimized beam waists and divergences. A beam-equalization system is designed and demonstrated for a typical asymmetrical beam of a laser diode bar. In the experiment an emission beam with dimensions of 1 µm × 10 mm and half-divergences of 148 mrad × 576 mrad in the far field is transformed into an almost-square distribution with dimensions of ∼12 mm × 12 mm and half-divergences of ∼2 mrad × 2 mrad, which confirm the effectiveness of the proposed technique.

© 2005 Optical Society of America

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References

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  1. See http://www.cymer.com for more information, or contact Cymer, Inc., 16750 Via Del Compo Court, San Diego, Calif. 92127-1712.
  2. H.-G. Treusch, A. Ovtchinnikov, X. He, M. Kanskar, J. Mott, S. Yang, “High-brightness semiconductor laser sources for materials processing: stacking, beam shaping, and bars,” IEEE J. Sel. Top. Quantum Electron. 6, 601–614 (2000).
    [CrossRef]
  3. P. Loosen, “Advanced concepts of using diode lasers in material processing,” in Lasers in Material Processing, L. H. J. F. Backmann, ed., Proc. SPIE3097, 480–485 (1997).
  4. W. A. Clarkson, D. C. Hanna, “Two-mirror beam-shaping technique for high-power diode bars,” Opt. Lett. 21, 375–377 (1996).
    [CrossRef] [PubMed]
  5. K. Du, M. Baumann, B. Ehlers, H. G. Treusch, P. Loosen, “Fiber-coupling technique with micro step-mirrors for high-power diode-laser bars,” in Advanced Solid-State Lasers, C. R. Pollack, W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington, D.C., 1977), pp. 390–393.
  6. P. Y. Wang, “Beam-shaping optics deliver high-power beam,” Laser Focus World 37, 115–118 (2001).
  7. Y. Satoshi, D. Masahiro, C. Koichi, K. Tetsurou, S. Yoshimasa, “Optical path rotating device used with linear array laser diode and laser apparatus applied therewith,” U.S. patent5513201 (2July1996).
  8. D. L. Shealy, “Geometrical methods,” in Laser Beam Shaping: Theory and Techniques, M. D. Fred, C. H. Scott, eds. (Marcel-Dekker, New York, 2000), pp. 163–213.
  9. Commercial lens design software, ZEMAX Development Corp., 4901 Morena Boulevard, Suite 207, San Diego, Calif. 92117-7320.

2001 (1)

P. Y. Wang, “Beam-shaping optics deliver high-power beam,” Laser Focus World 37, 115–118 (2001).

2000 (1)

H.-G. Treusch, A. Ovtchinnikov, X. He, M. Kanskar, J. Mott, S. Yang, “High-brightness semiconductor laser sources for materials processing: stacking, beam shaping, and bars,” IEEE J. Sel. Top. Quantum Electron. 6, 601–614 (2000).
[CrossRef]

1996 (1)

Baumann, M.

K. Du, M. Baumann, B. Ehlers, H. G. Treusch, P. Loosen, “Fiber-coupling technique with micro step-mirrors for high-power diode-laser bars,” in Advanced Solid-State Lasers, C. R. Pollack, W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington, D.C., 1977), pp. 390–393.

Clarkson, W. A.

Du, K.

K. Du, M. Baumann, B. Ehlers, H. G. Treusch, P. Loosen, “Fiber-coupling technique with micro step-mirrors for high-power diode-laser bars,” in Advanced Solid-State Lasers, C. R. Pollack, W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington, D.C., 1977), pp. 390–393.

Ehlers, B.

K. Du, M. Baumann, B. Ehlers, H. G. Treusch, P. Loosen, “Fiber-coupling technique with micro step-mirrors for high-power diode-laser bars,” in Advanced Solid-State Lasers, C. R. Pollack, W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington, D.C., 1977), pp. 390–393.

Hanna, D. C.

He, X.

H.-G. Treusch, A. Ovtchinnikov, X. He, M. Kanskar, J. Mott, S. Yang, “High-brightness semiconductor laser sources for materials processing: stacking, beam shaping, and bars,” IEEE J. Sel. Top. Quantum Electron. 6, 601–614 (2000).
[CrossRef]

Kanskar, M.

H.-G. Treusch, A. Ovtchinnikov, X. He, M. Kanskar, J. Mott, S. Yang, “High-brightness semiconductor laser sources for materials processing: stacking, beam shaping, and bars,” IEEE J. Sel. Top. Quantum Electron. 6, 601–614 (2000).
[CrossRef]

Koichi, C.

Y. Satoshi, D. Masahiro, C. Koichi, K. Tetsurou, S. Yoshimasa, “Optical path rotating device used with linear array laser diode and laser apparatus applied therewith,” U.S. patent5513201 (2July1996).

Loosen, P.

K. Du, M. Baumann, B. Ehlers, H. G. Treusch, P. Loosen, “Fiber-coupling technique with micro step-mirrors for high-power diode-laser bars,” in Advanced Solid-State Lasers, C. R. Pollack, W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington, D.C., 1977), pp. 390–393.

P. Loosen, “Advanced concepts of using diode lasers in material processing,” in Lasers in Material Processing, L. H. J. F. Backmann, ed., Proc. SPIE3097, 480–485 (1997).

Masahiro, D.

Y. Satoshi, D. Masahiro, C. Koichi, K. Tetsurou, S. Yoshimasa, “Optical path rotating device used with linear array laser diode and laser apparatus applied therewith,” U.S. patent5513201 (2July1996).

Mott, J.

H.-G. Treusch, A. Ovtchinnikov, X. He, M. Kanskar, J. Mott, S. Yang, “High-brightness semiconductor laser sources for materials processing: stacking, beam shaping, and bars,” IEEE J. Sel. Top. Quantum Electron. 6, 601–614 (2000).
[CrossRef]

Ovtchinnikov, A.

H.-G. Treusch, A. Ovtchinnikov, X. He, M. Kanskar, J. Mott, S. Yang, “High-brightness semiconductor laser sources for materials processing: stacking, beam shaping, and bars,” IEEE J. Sel. Top. Quantum Electron. 6, 601–614 (2000).
[CrossRef]

Satoshi, Y.

Y. Satoshi, D. Masahiro, C. Koichi, K. Tetsurou, S. Yoshimasa, “Optical path rotating device used with linear array laser diode and laser apparatus applied therewith,” U.S. patent5513201 (2July1996).

Shealy, D. L.

D. L. Shealy, “Geometrical methods,” in Laser Beam Shaping: Theory and Techniques, M. D. Fred, C. H. Scott, eds. (Marcel-Dekker, New York, 2000), pp. 163–213.

Tetsurou, K.

Y. Satoshi, D. Masahiro, C. Koichi, K. Tetsurou, S. Yoshimasa, “Optical path rotating device used with linear array laser diode and laser apparatus applied therewith,” U.S. patent5513201 (2July1996).

Treusch, H. G.

K. Du, M. Baumann, B. Ehlers, H. G. Treusch, P. Loosen, “Fiber-coupling technique with micro step-mirrors for high-power diode-laser bars,” in Advanced Solid-State Lasers, C. R. Pollack, W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington, D.C., 1977), pp. 390–393.

Treusch, H.-G.

H.-G. Treusch, A. Ovtchinnikov, X. He, M. Kanskar, J. Mott, S. Yang, “High-brightness semiconductor laser sources for materials processing: stacking, beam shaping, and bars,” IEEE J. Sel. Top. Quantum Electron. 6, 601–614 (2000).
[CrossRef]

Wang, P. Y.

P. Y. Wang, “Beam-shaping optics deliver high-power beam,” Laser Focus World 37, 115–118 (2001).

Yang, S.

H.-G. Treusch, A. Ovtchinnikov, X. He, M. Kanskar, J. Mott, S. Yang, “High-brightness semiconductor laser sources for materials processing: stacking, beam shaping, and bars,” IEEE J. Sel. Top. Quantum Electron. 6, 601–614 (2000).
[CrossRef]

Yoshimasa, S.

Y. Satoshi, D. Masahiro, C. Koichi, K. Tetsurou, S. Yoshimasa, “Optical path rotating device used with linear array laser diode and laser apparatus applied therewith,” U.S. patent5513201 (2July1996).

IEEE J. Sel. Top. Quantum Electron. (1)

H.-G. Treusch, A. Ovtchinnikov, X. He, M. Kanskar, J. Mott, S. Yang, “High-brightness semiconductor laser sources for materials processing: stacking, beam shaping, and bars,” IEEE J. Sel. Top. Quantum Electron. 6, 601–614 (2000).
[CrossRef]

Laser Focus World (1)

P. Y. Wang, “Beam-shaping optics deliver high-power beam,” Laser Focus World 37, 115–118 (2001).

Opt. Lett. (1)

Other (6)

K. Du, M. Baumann, B. Ehlers, H. G. Treusch, P. Loosen, “Fiber-coupling technique with micro step-mirrors for high-power diode-laser bars,” in Advanced Solid-State Lasers, C. R. Pollack, W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington, D.C., 1977), pp. 390–393.

P. Loosen, “Advanced concepts of using diode lasers in material processing,” in Lasers in Material Processing, L. H. J. F. Backmann, ed., Proc. SPIE3097, 480–485 (1997).

Y. Satoshi, D. Masahiro, C. Koichi, K. Tetsurou, S. Yoshimasa, “Optical path rotating device used with linear array laser diode and laser apparatus applied therewith,” U.S. patent5513201 (2July1996).

D. L. Shealy, “Geometrical methods,” in Laser Beam Shaping: Theory and Techniques, M. D. Fred, C. H. Scott, eds. (Marcel-Dekker, New York, 2000), pp. 163–213.

Commercial lens design software, ZEMAX Development Corp., 4901 Morena Boulevard, Suite 207, San Diego, Calif. 92117-7320.

See http://www.cymer.com for more information, or contact Cymer, Inc., 16750 Via Del Compo Court, San Diego, Calif. 92127-1712.

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Figures (4)

Fig. 1
Fig. 1

Micrograting-array beam shaper.

Fig. 2
Fig. 2

Beam-shaping arrangement for a 40-W laser diode (LD) for realization of bar symmetrical beams. BGA, blazed grating array.

Fig. 3
Fig. 3

Illustration of simulated beam distributions transformed by the micrograting array with ideal and smile laser diode bars. The virtual detector is located several millimeters behind the slow-axis recollimating lens. The shaped beam dimensions are 10.0 mm wide by 11.8 mm high for (b), (d)–(f). (a) Beam distributions without transformation in the far field are narrow strips 18 mm long and 0.5 mm wide. (b) Beam distributions with an ideal diode as the source. (c) Ideal layout of the laser diode bar is shown in (i). Typical smile bar with one curve and two curves is shown in panels (ii) and (iii), respectively. (d) Beam distributions with a smile diode as the source, whose shape is shown in panel (ii) of (c). The smile error is 2.5 µm, and we can see that beam separations are nonuniform because of the bar bow. (e) Beam distributions with a smile diode as the source, whose shape is shown in panel (iii) of (c). The smile error is 2.5 µm, and we can see that the central beams are compact and the marginal beams are loose. (f) When the smile error exceeds 3 µm, some subbeams overlap one another, which invalidates the gratings. Here the beam distributions have a smile error of 5 µm, and we can see that the central beams are mixed.

Fig. 4
Fig. 4

Experimental photos of beam shaping: (a) beam without shaping and (b) beam after shaping, where patterns (a) and (b) are located at the same positions as the virtual detector described in Fig. 3. For pattern (a), the beam is approximately 19 mm × 0.6 mm. For pattern (b), the beam is approximately 12 mm × 12 mm and the beam divergences of the half-angles are ∼2 mrad in both directions.

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