In this Letter, a 10 mu m quantum cascade laser operating in the intrapulse mode is used observe rapid passage (RP) effects within a 40 cm single-pass gas cell containing low pressures of NH3. The laser tuning range allows the rotational states J = 2 with K = 0, 1, and 2 to be probed. We show that the RP structures change as a function of optical density and that the magnitude of the delay in the switch from absorption to emission as a function of increased gas pressure is dependent upon the initial value of K. These measurements are qualitatively well modeled using the Maxwell-Bloch equations.
- laser radtiation
Northern, J. H., Ritchie, G. A. D., Smakman, E. P., van Helden, J. H., Cockburn, J., & Duxbury, G. (2010). Rapid passage signals induced by chirped quantum cascade laser radiation: K state dependent-delay effects in the nu(2) band of NH3. Optics Letters, 35(16), 2750-2752. https://doi.org/10.1364/OL.35.002750