Rapid passage signals induced by chirped quantum cascade laser radiation: K state dependent-delay effects in the nu(2) band of NH3

Northern, J. H. and Ritchie, G. A. D. and Smakman, E. P. and van Helden, J. H. and Cockburn, J. and 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). pp. 2750-2752. ISSN 0146-9592

Abstract

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.

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