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Journal of the Optical Society of America B

Journal of the Optical Society of America B


  • Vol. 2, Iss. 5 — May. 1, 1985
  • pp: 807–814

Dynamics of the N2O laser as measured with a tunable-diode laser

K. E. Fox and J. Reid  »View Author Affiliations

JOSA B, Vol. 2, Issue 5, pp. 807-814 (1985)

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A tunable-diode laser operating in the 2120–2350-cm−1 wave-number region is used to probe a conventional cw N2O laser discharge. Absorption lines in more than 10 different vibrational bands are observed, enabling us to determine vibrational populations in all levels of concern to the dynamics of the 10-μm N2O laser. The populations in the three normal modes of vibration of N2O are found to follow Boltzmann distributions, with the ν1 and ν2 modes maintaining a common vibrational temperature under all discharge conditions. The factors limiting the small-signal 10-μm gain are investigated in detail, and it is found that electron deexcitation of the 00°1 level is much more important than N2O dissociation.

© 1985 Optical Society of America

K. E. Fox and J. Reid, "Dynamics of the N2O laser as measured with a tunable-diode laser," J. Opt. Soc. Am. B 2, 807-814 (1985)

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  29. For convenience, vibrational bands will generally be identified by the lower level only, e.g., the (00°3–00°2) absorption band becomes the 00° 2 band.
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  31. The experimental points shown in Fig. 6 have been corrected for the absorption that occurs in the nondischarge portion of the tube. This correction is significant for the low-lying levels, such as 0110, but has little effect for levels such as 0330. The fitted value of α(00°0), as derived for Fig. 5, is used in the calculations of Nijl0. The combined effect of these procedures produces a linear least-squares fit to the data points, which need not pass exactly through the point (0, 0).
  32. The measured dissociation corresponds to the gas mixture leaving the discharge region, whereas the gas entering the discharge is undissociated. As the final products of N2O dissociation are N2 and O2,33 reformation of N2O is not expected to be significant.
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  34. Measurements made in CO2 discharges generally determine T2 to be ˜20 K higher than T,9 but part of this difference may arise from an underestimation of T through the use of inaccurate CO2-He pressure-broadening coefficients.22
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  36. Little change in T3 was observed over a pressure range from 7 to 14 Torr in the cw discharge, although we have observed a slight increase in T toward higher pressure. The pulsed measurements shown in Fig. 8 for N2O were taken at a pressure of 80 Torr.
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  39. The degree of dissociation at the entrance and exit of the discharge is known, and thus the exponential variation in N2O density exp(−dl) along the length of the discharge tube can be calculated. The average value of the exponential [1 − exp(−dL)]/dL is used to represent the average mixture in the discharge. L is the length of the discharge region.
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  41. Klaus Siemsen, National Research Council, Ottawa K1A 0R8, Canada (personal communication).
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  43. R. K. Brimacombe, "4.3−μm TE CO2 laser dynamics," Ph.D. dissertation (McMaster University, Hamilton, Ontario, Canada, 1985).
  44. T. A. Znotins, J. Reid, B. K. Garside, and E. A. Ballik, "4.3−μm TE CO2 laser," Opt. Lett. 4, 253–255 (1979).

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