Abstract

Four transitions from a cw CO2 laser were used to pump pure NH3 and obtain cw lasing in the 12-μm region. The pump frequencies were offset by as much as 1.35 GHz from the absorbing transitions in NH3, and a Raman process was generally responsible for the 12-μm gain. At high pump intensity several watts of 12-μm output were obtained, while threshold operation was achieved with less than 1 W of pump power.

© 1986 Optical Society of America

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  1. C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 725 (1984).
    [CrossRef]
  2. C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 380 (1984).
    [CrossRef]
  3. K. J. Siemsen, J. Reid, D. J. Danagher, “Improved cw lasers in the 11- to 13-μm wavelength region produced by optically pumping NH3,” Appl. Opt. (to be published).
  4. K. J. Siemsen, J. Reid, Opt. Lett. 10, 594 (1985).
    [CrossRef] [PubMed]
  5. C. Rolland, J. Reid, B. K. Garside, H. D. Morrison, P. E. Jessop, Appl. Opt. 23, 87 (1984).
    [CrossRef] [PubMed]
  6. H. D. Morrison, Ph.D. dissertation (McMaster University, Hamilton, Ont., Canada, 1984).
  7. E. M. Frank, C. O. Weiss, K. J. Siemsen, M. Grinda, G. D. Willenberg, Opt. Lett. 7, 96 (1982).
    [CrossRef] [PubMed]
  8. P. K. Gupta, A. K. Kar, M. R. Taghizaden, R. G. Harrison, Appl. Phys. Lett. 39, 32 (1981).
    [CrossRef]
  9. C. Rolland, J. Reid, B. K. Garside, IEEE J. Quantum Electron. QE-18, 182 (1982).
    [CrossRef]
  10. Calculations based on the model described in Ref. 5 predict that the round-trip gain with 30-W pump power is ~8%, just sufficient to overcome mirror and waveguide losses.
  11. C. Rolland, B. K. Garside, J. Reid, Appl. Opt. 24, 13 (1985).
    [CrossRef] [PubMed]
  12. R. L. Poynter, J. S. Margolis, Mol. Phys. 51, 393 (1984).
    [CrossRef]
  13. F. W. Taylor, J. Quant. Spectrosc. Radiat. Transfer 13, 1181 (1973).
    [CrossRef]
  14. J. Reid, K. J. Siemsen, J. Appl. Phys. 48, 2712 (1977).
    [CrossRef]
  15. T. A. Znotins, J. Reid, B. K. Garside, E. A. Ballik, Opt. Lett. 5, 528 (1980).
    [CrossRef] [PubMed]
  16. For these measurements the chopper shown in Fig. 1 was operated with a 20:1 duty cycle to prevent optical damage to the AOM. Identical results were obtained with a 10:1 duty cycle, and no thermal problems are expected even in true cw operation.1 All measured powers are converted to the cw value.
  17. Clearly the optimum offset will depend on the available pump power. It is somewhat fortuitous that the optimum offset for ~30-W pump power appears to be close to 180 MHz—the value used by Rolland et al. in their original experiments on cw Raman lasing.1 When much more power is available, as is the case with pulsed CO2 lasers, efficient lasing has been attained with an offset of 1.35 GHz,8 and lasing has been achieved with offsets as large as 5 GHz.6

1985 (2)

1984 (4)

C. Rolland, J. Reid, B. K. Garside, H. D. Morrison, P. E. Jessop, Appl. Opt. 23, 87 (1984).
[CrossRef] [PubMed]

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 725 (1984).
[CrossRef]

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 380 (1984).
[CrossRef]

R. L. Poynter, J. S. Margolis, Mol. Phys. 51, 393 (1984).
[CrossRef]

1982 (2)

1981 (1)

P. K. Gupta, A. K. Kar, M. R. Taghizaden, R. G. Harrison, Appl. Phys. Lett. 39, 32 (1981).
[CrossRef]

1980 (1)

1977 (1)

J. Reid, K. J. Siemsen, J. Appl. Phys. 48, 2712 (1977).
[CrossRef]

1973 (1)

F. W. Taylor, J. Quant. Spectrosc. Radiat. Transfer 13, 1181 (1973).
[CrossRef]

Ballik, E. A.

Danagher, D. J.

K. J. Siemsen, J. Reid, D. J. Danagher, “Improved cw lasers in the 11- to 13-μm wavelength region produced by optically pumping NH3,” Appl. Opt. (to be published).

Frank, E. M.

Garside, B. K.

C. Rolland, B. K. Garside, J. Reid, Appl. Opt. 24, 13 (1985).
[CrossRef] [PubMed]

C. Rolland, J. Reid, B. K. Garside, H. D. Morrison, P. E. Jessop, Appl. Opt. 23, 87 (1984).
[CrossRef] [PubMed]

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 725 (1984).
[CrossRef]

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 380 (1984).
[CrossRef]

C. Rolland, J. Reid, B. K. Garside, IEEE J. Quantum Electron. QE-18, 182 (1982).
[CrossRef]

T. A. Znotins, J. Reid, B. K. Garside, E. A. Ballik, Opt. Lett. 5, 528 (1980).
[CrossRef] [PubMed]

Grinda, M.

Gupta, P. K.

P. K. Gupta, A. K. Kar, M. R. Taghizaden, R. G. Harrison, Appl. Phys. Lett. 39, 32 (1981).
[CrossRef]

Harrison, R. G.

P. K. Gupta, A. K. Kar, M. R. Taghizaden, R. G. Harrison, Appl. Phys. Lett. 39, 32 (1981).
[CrossRef]

Jessop, P. E.

Kar, A. K.

P. K. Gupta, A. K. Kar, M. R. Taghizaden, R. G. Harrison, Appl. Phys. Lett. 39, 32 (1981).
[CrossRef]

Margolis, J. S.

R. L. Poynter, J. S. Margolis, Mol. Phys. 51, 393 (1984).
[CrossRef]

Morrison, H. D.

C. Rolland, J. Reid, B. K. Garside, H. D. Morrison, P. E. Jessop, Appl. Opt. 23, 87 (1984).
[CrossRef] [PubMed]

H. D. Morrison, Ph.D. dissertation (McMaster University, Hamilton, Ont., Canada, 1984).

Poynter, R. L.

R. L. Poynter, J. S. Margolis, Mol. Phys. 51, 393 (1984).
[CrossRef]

Reid, J.

K. J. Siemsen, J. Reid, Opt. Lett. 10, 594 (1985).
[CrossRef] [PubMed]

C. Rolland, B. K. Garside, J. Reid, Appl. Opt. 24, 13 (1985).
[CrossRef] [PubMed]

C. Rolland, J. Reid, B. K. Garside, H. D. Morrison, P. E. Jessop, Appl. Opt. 23, 87 (1984).
[CrossRef] [PubMed]

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 380 (1984).
[CrossRef]

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 725 (1984).
[CrossRef]

C. Rolland, J. Reid, B. K. Garside, IEEE J. Quantum Electron. QE-18, 182 (1982).
[CrossRef]

T. A. Znotins, J. Reid, B. K. Garside, E. A. Ballik, Opt. Lett. 5, 528 (1980).
[CrossRef] [PubMed]

J. Reid, K. J. Siemsen, J. Appl. Phys. 48, 2712 (1977).
[CrossRef]

K. J. Siemsen, J. Reid, D. J. Danagher, “Improved cw lasers in the 11- to 13-μm wavelength region produced by optically pumping NH3,” Appl. Opt. (to be published).

Rolland, C.

C. Rolland, B. K. Garside, J. Reid, Appl. Opt. 24, 13 (1985).
[CrossRef] [PubMed]

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 725 (1984).
[CrossRef]

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 380 (1984).
[CrossRef]

C. Rolland, J. Reid, B. K. Garside, H. D. Morrison, P. E. Jessop, Appl. Opt. 23, 87 (1984).
[CrossRef] [PubMed]

C. Rolland, J. Reid, B. K. Garside, IEEE J. Quantum Electron. QE-18, 182 (1982).
[CrossRef]

Siemsen, K. J.

K. J. Siemsen, J. Reid, Opt. Lett. 10, 594 (1985).
[CrossRef] [PubMed]

E. M. Frank, C. O. Weiss, K. J. Siemsen, M. Grinda, G. D. Willenberg, Opt. Lett. 7, 96 (1982).
[CrossRef] [PubMed]

J. Reid, K. J. Siemsen, J. Appl. Phys. 48, 2712 (1977).
[CrossRef]

K. J. Siemsen, J. Reid, D. J. Danagher, “Improved cw lasers in the 11- to 13-μm wavelength region produced by optically pumping NH3,” Appl. Opt. (to be published).

Taghizaden, M. R.

P. K. Gupta, A. K. Kar, M. R. Taghizaden, R. G. Harrison, Appl. Phys. Lett. 39, 32 (1981).
[CrossRef]

Taylor, F. W.

F. W. Taylor, J. Quant. Spectrosc. Radiat. Transfer 13, 1181 (1973).
[CrossRef]

Weiss, C. O.

Willenberg, G. D.

Znotins, T. A.

Appl. Opt. (2)

Appl. Phys. Lett. (3)

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 725 (1984).
[CrossRef]

C. Rolland, J. Reid, B. K. Garside, Appl. Phys. Lett. 44, 380 (1984).
[CrossRef]

P. K. Gupta, A. K. Kar, M. R. Taghizaden, R. G. Harrison, Appl. Phys. Lett. 39, 32 (1981).
[CrossRef]

IEEE J. Quantum Electron. (1)

C. Rolland, J. Reid, B. K. Garside, IEEE J. Quantum Electron. QE-18, 182 (1982).
[CrossRef]

J. Appl. Phys. (1)

J. Reid, K. J. Siemsen, J. Appl. Phys. 48, 2712 (1977).
[CrossRef]

J. Quant. Spectrosc. Radiat. Transfer (1)

F. W. Taylor, J. Quant. Spectrosc. Radiat. Transfer 13, 1181 (1973).
[CrossRef]

Mol. Phys. (1)

R. L. Poynter, J. S. Margolis, Mol. Phys. 51, 393 (1984).
[CrossRef]

Opt. Lett. (3)

Other (5)

H. D. Morrison, Ph.D. dissertation (McMaster University, Hamilton, Ont., Canada, 1984).

For these measurements the chopper shown in Fig. 1 was operated with a 20:1 duty cycle to prevent optical damage to the AOM. Identical results were obtained with a 10:1 duty cycle, and no thermal problems are expected even in true cw operation.1 All measured powers are converted to the cw value.

Clearly the optimum offset will depend on the available pump power. It is somewhat fortuitous that the optimum offset for ~30-W pump power appears to be close to 180 MHz—the value used by Rolland et al. in their original experiments on cw Raman lasing.1 When much more power is available, as is the case with pulsed CO2 lasers, efficient lasing has been attained with an offset of 1.35 GHz,8 and lasing has been achieved with offsets as large as 5 GHz.6

Calculations based on the model described in Ref. 5 predict that the round-trip gain with 30-W pump power is ~8%, just sufficient to overcome mirror and waveguide losses.

K. J. Siemsen, J. Reid, D. J. Danagher, “Improved cw lasers in the 11- to 13-μm wavelength region produced by optically pumping NH3,” Appl. Opt. (to be published).

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Figures (3)

Fig. 1
Fig. 1

Schematic diagram of the apparatus used to optically pump NH3. The solid line shows the path of the beam when the low-loss cavity was pumped. The dashed line indicates the beam path in the other configurations. The dichroic mirrors, M0’s, have a transmission of ~90% at 9 μm and reflect ~98% of the 12-μm radiation. The output coupler M1 is chosen to optimize the output power on the different transitions. The insert shows the arrangement when the acousto-optic modulator (AOM) is used. The arrow indicates the direction of propagation of the acoustic wave in the modulator. PZT, piezoelectric translator.

Fig. 2
Fig. 2

Calculations of small-signal gain as a function of offset with an incident 9-μm intensity of 500 W/cm2. Relaxation rates and energy levels are taken from Refs. 1113. (a) Comparison of gain for different values of J when pumping the aR(J, 0) line and lasing on the aP(J + 2, 0) line. (b) Gain for different values of K when pumping the sR(5, K) transition and lasing on the sP(7, K) transition. The operating points of three of the lasers described in this Letter are indicated by asterisks.

Fig. 3
Fig. 3

Variation of 12-μm output power16 as a function of CO2 input power at different pump offsets. For clarity, only two of the four cases observed experimentally are shown. The 12-μm cavity contains a 1.0-m-long, 2.5-mm-bore capillary tube, and the output mirror M1 transmits ~43% of the 12-μm radiation. The insert shows the principal NH3 vibrational–rotational energy levels involved in the laser system.

Tables (1)

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Table 1 Optimum Output Powers Produced by Optically Pumping 14NH3a

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