Abstract

We report a narrow-linewidth ZnGeP2 (ZGP) optical parametric oscillator (OPO). It employs a Q-switched Nd:YAG-laser-pumped LiNbO3 OPO with an output at λ=2.55 µm that is used as a pump for the ZGP OPO. With the singly resonant type II ZGP OPO cavity containing a diffraction grating and a Si etalon, we achieved mid-IR tunability from 3.7 to 8 µm with an output linewidth of ∼0.1 cm-1, corresponding to ∼3 axial cavity modes. We have also demonstrated that such a narrow-linewidth OPO can be achieved with a fairly broadband (∼15 cm-1) pump.

© 2001 Optical Society of America

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  1. D. N. Nikogosyan, Properties of Optical and Laser-Related Materials. A Handbook (Wiley, Chichester, 1997), pp. 133–140.
  2. P. G. Schunemann, P. A. Budni, L. Pomeranz, M. G. Knights, T. M. Pollak, and E. P. Chicklis, “Improved ZnGeP2 for high power OPO’s,” in Advanced Solid State Lasers, C. R. Pollock and W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1997), pp. 253–255.
  3. I. Zwieback, J. Maffetone, and W. Ruderman, “Growth of high quality ZnGeP2 single crystals,” Naval Research Laboratory, , Northvale, N.J., 1995.
  4. T. Allik, S. Chandra, D. M. Rines, P. G. Schunemann, J. A. Hutchinson, and R. Utano, “Tunable 7–12-µm optical parametric oscillator using a Cr, Er:YSGG laser to pump CdSe and ZnGeP2 crystals,” Opt. Lett. 22, 597–599 (1997).
    [Crossref] [PubMed]
  5. P. A. Budni, L. A. Pomeranz, M. L. Lemons, P. G. Schunemann, T. M. Pollak, and E. P. Chicklis, “10 W mid-IR holmium pumped ZnGeP2 OPO,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 90–92.
  6. J. A. C. Terry, K. J. McEwan, and M. J. P. Payne, “A tandem OPO route to the mid-IR,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 99–101.
  7. P. B. Phua, K. S. Lai, R. F. Wu, and T. C. Chong, “Coupled tandem optical parametric oscillator (OPO): an OPO within an OPO,” Opt. Lett. 23, 1262–1264 (1998).
    [Crossref]
  8. E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.
  9. K. L. Vodopyanov, F. Ganikhanov, J. P. Maffetone, I. Zwieback, and W. Ruderman, “ZnGeP2 optical parametric oscillator with 3.8–12.4-µm tunability,” Opt. Lett. 25, 841–843 (2000).
    [Crossref]
  10. P. A. Budni, L. A. Pomeranz, M. L. Lemons, C. A. Miller, J. R. Mosto, and E. P. Chicklis, “Efficient mid-infrared laser using 1.9-µm-pumped Ho:YAG and ZnGeP2 optical parametric oscillator,” J. Opt. Soc. Am. B 17, 723–728 (2000).
    [Crossref]
  11. K. L. Vodopyanov, “Parametric generation of tunable infrared radiation in ZnGeP2 and GaSe pumped at 3 µm,” J. Opt. Soc. Am. B 10, 1723–1729 (1993).
    [Crossref]
  12. V. Petrov, F. Rotermund, F. Noack, and P. Schunemann, “Femtosecond parametric generation in ZnGeP2,” Opt. Lett. 24, 414–416 (1999).
    [Crossref]
  13. D. E. Zelmon, E. A. Hanning, and P. Schunemann, “Refractive index measurement and new Sellmeier coefficients of zinc germanium phosphide (ZnGeP2) from 2–9 microns with implications for phase matching in optical parametric oscillators,” in Infrared Applications of Semiconductors III, Vol. 607 of MRS Symposium Proceedings, M. O. Manesreh, B. J. H. Stadler, I. Ferguson, and Y.-H. Zhang, eds. (Materials Research Society, Pittsburgh, Pa., 2000), pp. 451–456 (2000).
  14. S. J. Brosnan and R. L. Byer, “Optical parametric oscillation threshold and linewidth studies,” IEEE J. Quantum Electron. QE-15, 415–431 (1979).
    [Crossref]

2000 (2)

1999 (1)

1998 (1)

1997 (1)

1993 (1)

1979 (1)

S. J. Brosnan and R. L. Byer, “Optical parametric oscillation threshold and linewidth studies,” IEEE J. Quantum Electron. QE-15, 415–431 (1979).
[Crossref]

Allik, T.

Berg, J.

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

Bosenberg, W.

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

Brosnan, S. J.

S. J. Brosnan and R. L. Byer, “Optical parametric oscillation threshold and linewidth studies,” IEEE J. Quantum Electron. QE-15, 415–431 (1979).
[Crossref]

Budni, P. A.

P. A. Budni, L. A. Pomeranz, M. L. Lemons, C. A. Miller, J. R. Mosto, and E. P. Chicklis, “Efficient mid-infrared laser using 1.9-µm-pumped Ho:YAG and ZnGeP2 optical parametric oscillator,” J. Opt. Soc. Am. B 17, 723–728 (2000).
[Crossref]

P. G. Schunemann, P. A. Budni, L. Pomeranz, M. G. Knights, T. M. Pollak, and E. P. Chicklis, “Improved ZnGeP2 for high power OPO’s,” in Advanced Solid State Lasers, C. R. Pollock and W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1997), pp. 253–255.

P. A. Budni, L. A. Pomeranz, M. L. Lemons, P. G. Schunemann, T. M. Pollak, and E. P. Chicklis, “10 W mid-IR holmium pumped ZnGeP2 OPO,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 90–92.

Byer, R. L.

S. J. Brosnan and R. L. Byer, “Optical parametric oscillation threshold and linewidth studies,” IEEE J. Quantum Electron. QE-15, 415–431 (1979).
[Crossref]

Chandra, S.

Cheung, E.

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

Chicklis, E. P.

P. A. Budni, L. A. Pomeranz, M. L. Lemons, C. A. Miller, J. R. Mosto, and E. P. Chicklis, “Efficient mid-infrared laser using 1.9-µm-pumped Ho:YAG and ZnGeP2 optical parametric oscillator,” J. Opt. Soc. Am. B 17, 723–728 (2000).
[Crossref]

P. A. Budni, L. A. Pomeranz, M. L. Lemons, P. G. Schunemann, T. M. Pollak, and E. P. Chicklis, “10 W mid-IR holmium pumped ZnGeP2 OPO,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 90–92.

P. G. Schunemann, P. A. Budni, L. Pomeranz, M. G. Knights, T. M. Pollak, and E. P. Chicklis, “Improved ZnGeP2 for high power OPO’s,” in Advanced Solid State Lasers, C. R. Pollock and W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1997), pp. 253–255.

Chong, T. C.

Ganikhanov, F.

Hanning, E. A.

D. E. Zelmon, E. A. Hanning, and P. Schunemann, “Refractive index measurement and new Sellmeier coefficients of zinc germanium phosphide (ZnGeP2) from 2–9 microns with implications for phase matching in optical parametric oscillators,” in Infrared Applications of Semiconductors III, Vol. 607 of MRS Symposium Proceedings, M. O. Manesreh, B. J. H. Stadler, I. Ferguson, and Y.-H. Zhang, eds. (Materials Research Society, Pittsburgh, Pa., 2000), pp. 451–456 (2000).

Hilyard, R.

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

Ho, J.

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

Hoefer, C.

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

Hutchinson, J. A.

Injeyan, H.

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

Knights, M. G.

P. G. Schunemann, P. A. Budni, L. Pomeranz, M. G. Knights, T. M. Pollak, and E. P. Chicklis, “Improved ZnGeP2 for high power OPO’s,” in Advanced Solid State Lasers, C. R. Pollock and W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1997), pp. 253–255.

Komine, H.

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

Lai, K. S.

Lemons, M. L.

P. A. Budni, L. A. Pomeranz, M. L. Lemons, C. A. Miller, J. R. Mosto, and E. P. Chicklis, “Efficient mid-infrared laser using 1.9-µm-pumped Ho:YAG and ZnGeP2 optical parametric oscillator,” J. Opt. Soc. Am. B 17, 723–728 (2000).
[Crossref]

P. A. Budni, L. A. Pomeranz, M. L. Lemons, P. G. Schunemann, T. M. Pollak, and E. P. Chicklis, “10 W mid-IR holmium pumped ZnGeP2 OPO,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 90–92.

Maffetone, J.

I. Zwieback, J. Maffetone, and W. Ruderman, “Growth of high quality ZnGeP2 single crystals,” Naval Research Laboratory, , Northvale, N.J., 1995.

Maffetone, J. P.

McEwan, K. J.

J. A. C. Terry, K. J. McEwan, and M. J. P. Payne, “A tandem OPO route to the mid-IR,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 99–101.

Miller, C. A.

Mosto, J. R.

Nikogosyan, D. N.

D. N. Nikogosyan, Properties of Optical and Laser-Related Materials. A Handbook (Wiley, Chichester, 1997), pp. 133–140.

Noack, F.

Palese, S.

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

Payne, M. J. P.

J. A. C. Terry, K. J. McEwan, and M. J. P. Payne, “A tandem OPO route to the mid-IR,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 99–101.

Petrov, V.

Phua, P. B.

Pollak, T. M.

P. A. Budni, L. A. Pomeranz, M. L. Lemons, P. G. Schunemann, T. M. Pollak, and E. P. Chicklis, “10 W mid-IR holmium pumped ZnGeP2 OPO,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 90–92.

P. G. Schunemann, P. A. Budni, L. Pomeranz, M. G. Knights, T. M. Pollak, and E. P. Chicklis, “Improved ZnGeP2 for high power OPO’s,” in Advanced Solid State Lasers, C. R. Pollock and W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1997), pp. 253–255.

Pomeranz, L.

P. G. Schunemann, P. A. Budni, L. Pomeranz, M. G. Knights, T. M. Pollak, and E. P. Chicklis, “Improved ZnGeP2 for high power OPO’s,” in Advanced Solid State Lasers, C. R. Pollock and W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1997), pp. 253–255.

Pomeranz, L. A.

P. A. Budni, L. A. Pomeranz, M. L. Lemons, C. A. Miller, J. R. Mosto, and E. P. Chicklis, “Efficient mid-infrared laser using 1.9-µm-pumped Ho:YAG and ZnGeP2 optical parametric oscillator,” J. Opt. Soc. Am. B 17, 723–728 (2000).
[Crossref]

P. A. Budni, L. A. Pomeranz, M. L. Lemons, P. G. Schunemann, T. M. Pollak, and E. P. Chicklis, “10 W mid-IR holmium pumped ZnGeP2 OPO,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 90–92.

Rines, D. M.

Rotermund, F.

Ruderman, W.

K. L. Vodopyanov, F. Ganikhanov, J. P. Maffetone, I. Zwieback, and W. Ruderman, “ZnGeP2 optical parametric oscillator with 3.8–12.4-µm tunability,” Opt. Lett. 25, 841–843 (2000).
[Crossref]

I. Zwieback, J. Maffetone, and W. Ruderman, “Growth of high quality ZnGeP2 single crystals,” Naval Research Laboratory, , Northvale, N.J., 1995.

Schunemann, P.

V. Petrov, F. Rotermund, F. Noack, and P. Schunemann, “Femtosecond parametric generation in ZnGeP2,” Opt. Lett. 24, 414–416 (1999).
[Crossref]

D. E. Zelmon, E. A. Hanning, and P. Schunemann, “Refractive index measurement and new Sellmeier coefficients of zinc germanium phosphide (ZnGeP2) from 2–9 microns with implications for phase matching in optical parametric oscillators,” in Infrared Applications of Semiconductors III, Vol. 607 of MRS Symposium Proceedings, M. O. Manesreh, B. J. H. Stadler, I. Ferguson, and Y.-H. Zhang, eds. (Materials Research Society, Pittsburgh, Pa., 2000), pp. 451–456 (2000).

Schunemann, P. G.

T. Allik, S. Chandra, D. M. Rines, P. G. Schunemann, J. A. Hutchinson, and R. Utano, “Tunable 7–12-µm optical parametric oscillator using a Cr, Er:YSGG laser to pump CdSe and ZnGeP2 crystals,” Opt. Lett. 22, 597–599 (1997).
[Crossref] [PubMed]

P. A. Budni, L. A. Pomeranz, M. L. Lemons, P. G. Schunemann, T. M. Pollak, and E. P. Chicklis, “10 W mid-IR holmium pumped ZnGeP2 OPO,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 90–92.

P. G. Schunemann, P. A. Budni, L. Pomeranz, M. G. Knights, T. M. Pollak, and E. P. Chicklis, “Improved ZnGeP2 for high power OPO’s,” in Advanced Solid State Lasers, C. R. Pollock and W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1997), pp. 253–255.

Terry, J. A. C.

J. A. C. Terry, K. J. McEwan, and M. J. P. Payne, “A tandem OPO route to the mid-IR,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 99–101.

Utano, R.

Vodopyanov, K. L.

Wu, R. F.

Zelmon, D. E.

D. E. Zelmon, E. A. Hanning, and P. Schunemann, “Refractive index measurement and new Sellmeier coefficients of zinc germanium phosphide (ZnGeP2) from 2–9 microns with implications for phase matching in optical parametric oscillators,” in Infrared Applications of Semiconductors III, Vol. 607 of MRS Symposium Proceedings, M. O. Manesreh, B. J. H. Stadler, I. Ferguson, and Y.-H. Zhang, eds. (Materials Research Society, Pittsburgh, Pa., 2000), pp. 451–456 (2000).

Zwieback, I.

K. L. Vodopyanov, F. Ganikhanov, J. P. Maffetone, I. Zwieback, and W. Ruderman, “ZnGeP2 optical parametric oscillator with 3.8–12.4-µm tunability,” Opt. Lett. 25, 841–843 (2000).
[Crossref]

I. Zwieback, J. Maffetone, and W. Ruderman, “Growth of high quality ZnGeP2 single crystals,” Naval Research Laboratory, , Northvale, N.J., 1995.

IEEE J. Quantum Electron. (1)

S. J. Brosnan and R. L. Byer, “Optical parametric oscillation threshold and linewidth studies,” IEEE J. Quantum Electron. QE-15, 415–431 (1979).
[Crossref]

J. Opt. Soc. Am. B (2)

Opt. Lett. (4)

Other (7)

E. Cheung, S. Palese, H. Injeyan, C. Hoefer, J. Ho, R. Hilyard, H. Komine, J. Berg, and W. Bosenberg, “High-power conversion to mid-IR using KTP and ZGP OPOs,” in Advanced Solid-State Lasers, M. M. Fejer, H. Injeyan, and U. Keller, eds., Vol. 26 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1999), pp. 358–361.

P. A. Budni, L. A. Pomeranz, M. L. Lemons, P. G. Schunemann, T. M. Pollak, and E. P. Chicklis, “10 W mid-IR holmium pumped ZnGeP2 OPO,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 90–92.

J. A. C. Terry, K. J. McEwan, and M. J. P. Payne, “A tandem OPO route to the mid-IR,” in Advanced Solid State Lasers, W. R. Bosenberg and M. M. Fejer, eds., Vol. 19 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1998), pp. 99–101.

D. N. Nikogosyan, Properties of Optical and Laser-Related Materials. A Handbook (Wiley, Chichester, 1997), pp. 133–140.

P. G. Schunemann, P. A. Budni, L. Pomeranz, M. G. Knights, T. M. Pollak, and E. P. Chicklis, “Improved ZnGeP2 for high power OPO’s,” in Advanced Solid State Lasers, C. R. Pollock and W. R. Bosenberg, eds., Vol. 10 of OSA Trends in Optics and Photonics Series (Optical Society of America, Washington D.C., 1997), pp. 253–255.

I. Zwieback, J. Maffetone, and W. Ruderman, “Growth of high quality ZnGeP2 single crystals,” Naval Research Laboratory, , Northvale, N.J., 1995.

D. E. Zelmon, E. A. Hanning, and P. Schunemann, “Refractive index measurement and new Sellmeier coefficients of zinc germanium phosphide (ZnGeP2) from 2–9 microns with implications for phase matching in optical parametric oscillators,” in Infrared Applications of Semiconductors III, Vol. 607 of MRS Symposium Proceedings, M. O. Manesreh, B. J. H. Stadler, I. Ferguson, and Y.-H. Zhang, eds. (Materials Research Society, Pittsburgh, Pa., 2000), pp. 451–456 (2000).

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Figures (6)

Fig. 1
Fig. 1

Layout of the tandem mid-IR OPO. (a) LiNbO3 OPO. Mirrors M1 and M2 have HR for signal wave (1.5–2 µm) and HT for pump (1.064 µm) and idler (2.2–3.6 µm) waves. Mirror M3 is used for pump recycling and has HR at 1.064 µm and HT at signal and idler waves. (b) Simple ZGP OPO configuration. Mirror M4 has HR at signal wavelengths (3.3–4.8 µm) and HT for idler wavelengths (5.3–10.5 µm). Mirror M5 has HR at 2.55 µm and HT (> 80%) for both signal and idler wavelengths. M6 is a gold mirror with HR for all the three waves. (c) Narrow-linewidth ZGP OPO that uses a diffraction grating (blazed at 3.2 µm or at 6.4 µm) and an etalon.

Fig. 2
Fig. 2

(a) Theoretical ZGP type II angle tuning curves. Wavelength dependence of acceptance bandwidths with respect to the pump (near 2.55 µm) for (b) resonating and fixed signal and (c) for resonating and fixed idler. We assumed L(ZGP)=14 mm.

Fig. 3
Fig. 3

(a) Experimental type II OPO tuning curve (open circles) with respect to the tilt angle of ZGP (cut at θ0=70°). Theoretical tuning curves (solid curves) were calculated by using the Sellmeier equations of Zelmon et al.13 (b) Idler pulse bandwidth versus wavelength. Dashed line: calculated OPO gain bandwidth. Inset: idler pulse spectrum near λ=10.5 µm.

Fig. 4
Fig. 4

Spatial profile of the λ=6.7 µm idler beam detected at the distance of 75 cm from the OPO.

Fig. 5
Fig. 5

Output spectra of the ZGP OPO (a) near λ=4.3 µm and (b) 6.8 µm. Filled circles, no spectral-narrowing elements inside the OPO cavity; open circle, with a diffraction grating inside the cavity. Transmission interferograms (filled squares) of the output of the OPO containing both a grating and an etalon (c) near λ=4.3 µm and (d) 6.8 µm, passing through a 2-mm-thick Si etalon. Solid curves represent calculated results with the best-fit linewidths of 0.12 cm-1 and 0.13 cm-1, respectively.

Fig. 6
Fig. 6

Water vapor absorption spectrum (at saturated pressure at 60 °C in a cell length of 15 cm) taken near λ=6.2 µm with a narrow-linewidth ZGP OPO. Inset, absorption spectrum obtained with FTIR spectrometer (2 cm-1 resolution).

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