Abstract

The conversion efficiency in second-harmonic generation of an amplified beam in a master-oscillator power amplifier copper-vapor laser (CVL) is lower than that of the oscillator beam alone. This lower efficiency is often vaguely attributed to wave-front degradation in the amplifier. We investigate the role of wave-front degradation and thermal dephasing in the second-harmonic generation of a CVL from a β-barium borate crystal. Choosing two beams with constant intrapulse divergence, one from a generalized diffraction filtered resonator master oscillator alone and other obtained by amplifying oscillator by use of a power amplifier, we show that at low flux levels the decrease in efficiency is due to wave-front degradation. At a fundamental power above the critical power for thermal dephasing, the decrease is due to increased UV absorption and consequent thermal dephasing. Thermal dephasing is higher for the beam with the lower coherence width.

© 2005 Optical Society of America

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References

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  1. G. S. Evtushenko, V. O. Troitskii, “Effective conversion of copper vapour laser emission in β-BaB2O4,” J. Russ. Laser Res. 15, 28–33 (1994).
    [CrossRef]
  2. D. W. Coutts, D. J. W. Brown, “Production of high average power UV by second harmonic and sum frequency generation of copper vapour laser,” IEEE Sel. Top. Quantum Electron. 1, 768–777 (1995).
    [CrossRef]
  3. D. J. W. Brown, M. J. Withford, “High average power (15-W) 255-nm source based on second-harmonic generation of a copper vapor laser master oscillator power amplifier system in cesium lithium borate,” Opt. Lett. 26, 1885–1887 (2001).
    [CrossRef]
  4. A. A. Isaev, D. R. Jones, C. E. Little, G. G. Petrash, C. G. Whyte, K. I. Zemskov, “1.3 W average power at 255 nm by second harmonic generation in BBO pumped by a copper Hybrid laser,” Opt. Commun. 132, 302–306 (1996).
    [CrossRef]
  5. A. P. Sukhorukov, “Highly efficient optical harmonic generation,” in Proceedings of International Conference and School on “Laser and Applications Part 1,”I. Ursu, A. M. Prokhorov, eds. (CIP Press, Bucharest, Romania, 1983), pp. 243–266.
  6. R. Bhatnagar, S. K. Dixit, B. Singh, S. V. Nakhe, “Performance of a copper vapour laser with a self filtered unstable resonator,” Opt. Commun. 74, 93–95 (1989).
    [CrossRef]
  7. S. K. Dixit, J. K. Mittal, B. Singh, P. Saxena, R. Bhatnagar, “A generalized diffraction filtered resonator with a copper vapour laser,” Opt. Commun. 98, 91–94 (1993).
    [CrossRef]
  8. O. Prakash, G. N. Tiwari, S. K. Dixit, R. Bhatnagar, “Single pulse time resolved comparative study on the performance of a master oscillator power amplifier copper vapor laser system with generalized diffraction filtered and unstable resonator as master oscillator,” Appl. Opt. 42, 3538–3545 (2003).
    [CrossRef] [PubMed]
  9. J. J. Chang, “Copper laser oscillator with adjoint-coupled self filtering injection,” Opt. Lett. 20, 575–577 (1995).
    [CrossRef] [PubMed]
  10. O. Prakash, S. K. Dixit, R. Bhatangar, “On the role of coherence width and its evolution in a short pulse fundamental beam in second harmonic generation from beta barium borate,” IEEE J. Quantum Electron. 38, 603–613 (2002).
    [CrossRef]
  11. D. Eimerl, L. Davis, S. Velsko, “Optical, mechanical, and thermal properties of barium borate,” J. Appl. Phys. 62, 1968–1983 (1987).
    [CrossRef]
  12. Cleveland Crystal, Inc., “BBO crystal—beta barium borate and lithium borate,” technical leaflet (Cleveland Crystal, Highland Heights, Ohio, 1999).
  13. M. Okada, S. Ieiri, “Influence of self-induced thermal effects on second harmonic generation,” IEEE J. Quantum Electron. QE-7, 469–470 (1971).
    [CrossRef]
  14. N. Bloembergen, Nonlinear Optics (Benjamin, New York, 1965).

2003

2002

O. Prakash, S. K. Dixit, R. Bhatangar, “On the role of coherence width and its evolution in a short pulse fundamental beam in second harmonic generation from beta barium borate,” IEEE J. Quantum Electron. 38, 603–613 (2002).
[CrossRef]

2001

1996

A. A. Isaev, D. R. Jones, C. E. Little, G. G. Petrash, C. G. Whyte, K. I. Zemskov, “1.3 W average power at 255 nm by second harmonic generation in BBO pumped by a copper Hybrid laser,” Opt. Commun. 132, 302–306 (1996).
[CrossRef]

1995

D. W. Coutts, D. J. W. Brown, “Production of high average power UV by second harmonic and sum frequency generation of copper vapour laser,” IEEE Sel. Top. Quantum Electron. 1, 768–777 (1995).
[CrossRef]

J. J. Chang, “Copper laser oscillator with adjoint-coupled self filtering injection,” Opt. Lett. 20, 575–577 (1995).
[CrossRef] [PubMed]

1994

G. S. Evtushenko, V. O. Troitskii, “Effective conversion of copper vapour laser emission in β-BaB2O4,” J. Russ. Laser Res. 15, 28–33 (1994).
[CrossRef]

1993

S. K. Dixit, J. K. Mittal, B. Singh, P. Saxena, R. Bhatnagar, “A generalized diffraction filtered resonator with a copper vapour laser,” Opt. Commun. 98, 91–94 (1993).
[CrossRef]

1989

R. Bhatnagar, S. K. Dixit, B. Singh, S. V. Nakhe, “Performance of a copper vapour laser with a self filtered unstable resonator,” Opt. Commun. 74, 93–95 (1989).
[CrossRef]

1987

D. Eimerl, L. Davis, S. Velsko, “Optical, mechanical, and thermal properties of barium borate,” J. Appl. Phys. 62, 1968–1983 (1987).
[CrossRef]

1971

M. Okada, S. Ieiri, “Influence of self-induced thermal effects on second harmonic generation,” IEEE J. Quantum Electron. QE-7, 469–470 (1971).
[CrossRef]

Bhatangar, R.

O. Prakash, S. K. Dixit, R. Bhatangar, “On the role of coherence width and its evolution in a short pulse fundamental beam in second harmonic generation from beta barium borate,” IEEE J. Quantum Electron. 38, 603–613 (2002).
[CrossRef]

Bhatnagar, R.

O. Prakash, G. N. Tiwari, S. K. Dixit, R. Bhatnagar, “Single pulse time resolved comparative study on the performance of a master oscillator power amplifier copper vapor laser system with generalized diffraction filtered and unstable resonator as master oscillator,” Appl. Opt. 42, 3538–3545 (2003).
[CrossRef] [PubMed]

S. K. Dixit, J. K. Mittal, B. Singh, P. Saxena, R. Bhatnagar, “A generalized diffraction filtered resonator with a copper vapour laser,” Opt. Commun. 98, 91–94 (1993).
[CrossRef]

R. Bhatnagar, S. K. Dixit, B. Singh, S. V. Nakhe, “Performance of a copper vapour laser with a self filtered unstable resonator,” Opt. Commun. 74, 93–95 (1989).
[CrossRef]

Bloembergen, N.

N. Bloembergen, Nonlinear Optics (Benjamin, New York, 1965).

Brown, D. J. W.

D. J. W. Brown, M. J. Withford, “High average power (15-W) 255-nm source based on second-harmonic generation of a copper vapor laser master oscillator power amplifier system in cesium lithium borate,” Opt. Lett. 26, 1885–1887 (2001).
[CrossRef]

D. W. Coutts, D. J. W. Brown, “Production of high average power UV by second harmonic and sum frequency generation of copper vapour laser,” IEEE Sel. Top. Quantum Electron. 1, 768–777 (1995).
[CrossRef]

Chang, J. J.

Coutts, D. W.

D. W. Coutts, D. J. W. Brown, “Production of high average power UV by second harmonic and sum frequency generation of copper vapour laser,” IEEE Sel. Top. Quantum Electron. 1, 768–777 (1995).
[CrossRef]

Davis, L.

D. Eimerl, L. Davis, S. Velsko, “Optical, mechanical, and thermal properties of barium borate,” J. Appl. Phys. 62, 1968–1983 (1987).
[CrossRef]

Dixit, S. K.

O. Prakash, G. N. Tiwari, S. K. Dixit, R. Bhatnagar, “Single pulse time resolved comparative study on the performance of a master oscillator power amplifier copper vapor laser system with generalized diffraction filtered and unstable resonator as master oscillator,” Appl. Opt. 42, 3538–3545 (2003).
[CrossRef] [PubMed]

O. Prakash, S. K. Dixit, R. Bhatangar, “On the role of coherence width and its evolution in a short pulse fundamental beam in second harmonic generation from beta barium borate,” IEEE J. Quantum Electron. 38, 603–613 (2002).
[CrossRef]

S. K. Dixit, J. K. Mittal, B. Singh, P. Saxena, R. Bhatnagar, “A generalized diffraction filtered resonator with a copper vapour laser,” Opt. Commun. 98, 91–94 (1993).
[CrossRef]

R. Bhatnagar, S. K. Dixit, B. Singh, S. V. Nakhe, “Performance of a copper vapour laser with a self filtered unstable resonator,” Opt. Commun. 74, 93–95 (1989).
[CrossRef]

Eimerl, D.

D. Eimerl, L. Davis, S. Velsko, “Optical, mechanical, and thermal properties of barium borate,” J. Appl. Phys. 62, 1968–1983 (1987).
[CrossRef]

Evtushenko, G. S.

G. S. Evtushenko, V. O. Troitskii, “Effective conversion of copper vapour laser emission in β-BaB2O4,” J. Russ. Laser Res. 15, 28–33 (1994).
[CrossRef]

Ieiri, S.

M. Okada, S. Ieiri, “Influence of self-induced thermal effects on second harmonic generation,” IEEE J. Quantum Electron. QE-7, 469–470 (1971).
[CrossRef]

Isaev, A. A.

A. A. Isaev, D. R. Jones, C. E. Little, G. G. Petrash, C. G. Whyte, K. I. Zemskov, “1.3 W average power at 255 nm by second harmonic generation in BBO pumped by a copper Hybrid laser,” Opt. Commun. 132, 302–306 (1996).
[CrossRef]

Jones, D. R.

A. A. Isaev, D. R. Jones, C. E. Little, G. G. Petrash, C. G. Whyte, K. I. Zemskov, “1.3 W average power at 255 nm by second harmonic generation in BBO pumped by a copper Hybrid laser,” Opt. Commun. 132, 302–306 (1996).
[CrossRef]

Little, C. E.

A. A. Isaev, D. R. Jones, C. E. Little, G. G. Petrash, C. G. Whyte, K. I. Zemskov, “1.3 W average power at 255 nm by second harmonic generation in BBO pumped by a copper Hybrid laser,” Opt. Commun. 132, 302–306 (1996).
[CrossRef]

Mittal, J. K.

S. K. Dixit, J. K. Mittal, B. Singh, P. Saxena, R. Bhatnagar, “A generalized diffraction filtered resonator with a copper vapour laser,” Opt. Commun. 98, 91–94 (1993).
[CrossRef]

Nakhe, S. V.

R. Bhatnagar, S. K. Dixit, B. Singh, S. V. Nakhe, “Performance of a copper vapour laser with a self filtered unstable resonator,” Opt. Commun. 74, 93–95 (1989).
[CrossRef]

Okada, M.

M. Okada, S. Ieiri, “Influence of self-induced thermal effects on second harmonic generation,” IEEE J. Quantum Electron. QE-7, 469–470 (1971).
[CrossRef]

Petrash, G. G.

A. A. Isaev, D. R. Jones, C. E. Little, G. G. Petrash, C. G. Whyte, K. I. Zemskov, “1.3 W average power at 255 nm by second harmonic generation in BBO pumped by a copper Hybrid laser,” Opt. Commun. 132, 302–306 (1996).
[CrossRef]

Prakash, O.

O. Prakash, G. N. Tiwari, S. K. Dixit, R. Bhatnagar, “Single pulse time resolved comparative study on the performance of a master oscillator power amplifier copper vapor laser system with generalized diffraction filtered and unstable resonator as master oscillator,” Appl. Opt. 42, 3538–3545 (2003).
[CrossRef] [PubMed]

O. Prakash, S. K. Dixit, R. Bhatangar, “On the role of coherence width and its evolution in a short pulse fundamental beam in second harmonic generation from beta barium borate,” IEEE J. Quantum Electron. 38, 603–613 (2002).
[CrossRef]

Saxena, P.

S. K. Dixit, J. K. Mittal, B. Singh, P. Saxena, R. Bhatnagar, “A generalized diffraction filtered resonator with a copper vapour laser,” Opt. Commun. 98, 91–94 (1993).
[CrossRef]

Singh, B.

S. K. Dixit, J. K. Mittal, B. Singh, P. Saxena, R. Bhatnagar, “A generalized diffraction filtered resonator with a copper vapour laser,” Opt. Commun. 98, 91–94 (1993).
[CrossRef]

R. Bhatnagar, S. K. Dixit, B. Singh, S. V. Nakhe, “Performance of a copper vapour laser with a self filtered unstable resonator,” Opt. Commun. 74, 93–95 (1989).
[CrossRef]

Sukhorukov, A. P.

A. P. Sukhorukov, “Highly efficient optical harmonic generation,” in Proceedings of International Conference and School on “Laser and Applications Part 1,”I. Ursu, A. M. Prokhorov, eds. (CIP Press, Bucharest, Romania, 1983), pp. 243–266.

Tiwari, G. N.

Troitskii, V. O.

G. S. Evtushenko, V. O. Troitskii, “Effective conversion of copper vapour laser emission in β-BaB2O4,” J. Russ. Laser Res. 15, 28–33 (1994).
[CrossRef]

Velsko, S.

D. Eimerl, L. Davis, S. Velsko, “Optical, mechanical, and thermal properties of barium borate,” J. Appl. Phys. 62, 1968–1983 (1987).
[CrossRef]

Whyte, C. G.

A. A. Isaev, D. R. Jones, C. E. Little, G. G. Petrash, C. G. Whyte, K. I. Zemskov, “1.3 W average power at 255 nm by second harmonic generation in BBO pumped by a copper Hybrid laser,” Opt. Commun. 132, 302–306 (1996).
[CrossRef]

Withford, M. J.

Zemskov, K. I.

A. A. Isaev, D. R. Jones, C. E. Little, G. G. Petrash, C. G. Whyte, K. I. Zemskov, “1.3 W average power at 255 nm by second harmonic generation in BBO pumped by a copper Hybrid laser,” Opt. Commun. 132, 302–306 (1996).
[CrossRef]

Appl. Opt.

IEEE J. Quantum Electron.

O. Prakash, S. K. Dixit, R. Bhatangar, “On the role of coherence width and its evolution in a short pulse fundamental beam in second harmonic generation from beta barium borate,” IEEE J. Quantum Electron. 38, 603–613 (2002).
[CrossRef]

M. Okada, S. Ieiri, “Influence of self-induced thermal effects on second harmonic generation,” IEEE J. Quantum Electron. QE-7, 469–470 (1971).
[CrossRef]

IEEE Sel. Top. Quantum Electron.

D. W. Coutts, D. J. W. Brown, “Production of high average power UV by second harmonic and sum frequency generation of copper vapour laser,” IEEE Sel. Top. Quantum Electron. 1, 768–777 (1995).
[CrossRef]

J. Appl. Phys.

D. Eimerl, L. Davis, S. Velsko, “Optical, mechanical, and thermal properties of barium borate,” J. Appl. Phys. 62, 1968–1983 (1987).
[CrossRef]

J. Russ. Laser Res.

G. S. Evtushenko, V. O. Troitskii, “Effective conversion of copper vapour laser emission in β-BaB2O4,” J. Russ. Laser Res. 15, 28–33 (1994).
[CrossRef]

Opt. Commun.

A. A. Isaev, D. R. Jones, C. E. Little, G. G. Petrash, C. G. Whyte, K. I. Zemskov, “1.3 W average power at 255 nm by second harmonic generation in BBO pumped by a copper Hybrid laser,” Opt. Commun. 132, 302–306 (1996).
[CrossRef]

R. Bhatnagar, S. K. Dixit, B. Singh, S. V. Nakhe, “Performance of a copper vapour laser with a self filtered unstable resonator,” Opt. Commun. 74, 93–95 (1989).
[CrossRef]

S. K. Dixit, J. K. Mittal, B. Singh, P. Saxena, R. Bhatnagar, “A generalized diffraction filtered resonator with a copper vapour laser,” Opt. Commun. 98, 91–94 (1993).
[CrossRef]

Opt. Lett.

Other

A. P. Sukhorukov, “Highly efficient optical harmonic generation,” in Proceedings of International Conference and School on “Laser and Applications Part 1,”I. Ursu, A. M. Prokhorov, eds. (CIP Press, Bucharest, Romania, 1983), pp. 243–266.

Cleveland Crystal, Inc., “BBO crystal—beta barium borate and lithium borate,” technical leaflet (Cleveland Crystal, Highland Heights, Ohio, 1999).

N. Bloembergen, Nonlinear Optics (Benjamin, New York, 1965).

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Figures (9)

Fig. 1
Fig. 1

Schematic diagram of the experimental setup. Abbreviations are defined in text.

Fig. 2
Fig. 2

Variation of divergence of the fundamental beam within the pulse for a GDFR oscillator (A, δ = 1.0) and an amplified beam (B, δ = 0.75). The photographs show the corresponding streak scans.

Fig. 3
Fig. 3

Variation of conversion efficiency η for A, δ = 1.0 and B, δ = 0.75. C, [η(δ=1.0) − η(δ=0.75)] × 100/η(δ=1.0). Absorbed power per unit volume, D, δ = 1.0 and E, δ = 0.75, with the fundamental flux.

Fig. 4
Fig. 4

Temporal variation of intensity of fundamental (upper traces), depleted fundamental (middle traces), and SH (lower traces) pulses for amplified beam δ = 0.75 at powers of (a) 1.7, (b) 4.0, (c) 5.2, (d) 7.2, (e) 8.2, and (f) 11.0 W.

Fig. 5
Fig. 5

Variation of instantaneous conversion efficiency and flux for the amplified beam (δ = 0.75) at fundamental average powers of (a) 1.7, (b) 4.0, (c) 5.2, (d) 7.2, (e) 8.2, and (f) 11.0 W.

Fig. 6
Fig. 6

Variation of A, η(START) and B, ′(END) at constant instantaneous flux (20 MW/cm2) and C, η(START) < 5 ns (10 MW/cm2) with average fundamental power.

Fig. 7
Fig. 7

Variation of conversion efficiency estimated from η(DF) (filled circles), η(UV) (open circles), and η(DF) − η(UV) (filled diamonds) with average power at a flux of 20 MW/cm2 for (a) the start of the pulse (b) the end of the pulse.

Fig. 8
Fig. 8

Variation of conversion efficiency with fundamental flux for the oscillator beam (A, δ = 1.0, filled circles). The thicker line is for ηth = 1.0 and the amplified beam (B, δ = 0.75, open squares), and other thin curves correspond to various values of ηth.

Fig. 9
Fig. 9

Variation of conversion coefficient C with fundamental flux for δ = 1.0 and δ = 0.75.

Equations (2)

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P c = χ λ / { α L u [ ( Δ n ) / T ] } ,
η th = P 2 ω P ω = tanh 2 [ L u K 1 / 2 ( P ω A ) 1 / 2 sin ( Δ K L u / 2 ) ( Δ K L u / 2 ) ] ,

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