Bi-directional description of amplified spontaneous emission induced by three-photon absorption
2005 (English)In: Journal of the Optical Society of America. B, Optical physics, ISSN 0740-3224, Vol. 22, no 2, 385-393 p.Article in journal (Refereed) Published
A semiclassical dynamic theory of the nonlinear propagation of a few interacting intense light pulses is applied to study the nonlinear counterpropagation of amplified spontaneous emission (ASE) induced by three-photon absorption of short intense laser pulses in a chromophore solution. Several important results from the modeling are reached for the ASE process developing in the regime of strong saturation. Accounting for ASE in both forward and backward directions with respect to the pump pulse results in a smaller efficiency of nonlinear conversion for the forward ASE compared with the case in which forward emission is considered alone, something that results from the partial repump of the absorbed energy to the backward ASE component; the overall efficiency is nevertheless higher than for the forward emission considered alone. The efficiency of nonlinear conversion of the pump energy to the counterpropagating ASE pulses is strongly dependent on the concentration of active molecules so that a particular combination of concentration versus cell length optimizes the conversion coefficient. Under certain specified conditions, the ASE effect is found to be oscillatory; the origin of oscillations is dynamical competition between stimulated emission and off-resonant absorption. This result can be considered one of the possible explanations of the temporal fluctuations of the forward ASE pulse [Nature 415, 767 (2002)].
Place, publisher, year, edition, pages
2005. Vol. 22, no 2, 385-393 p.
Laser pulses, Light absorption, Light propagation, Mathematical models, Maxwell equations, Optical frequency conversion, Optical materials, Optical pumping, Oscillations, Photons, Spontaneous emission, Wave equations
IdentifiersURN: urn:nbn:se:kth:diva-5486DOI: 10.1364/JOSAB.22.000385ISI: 000226967800012ScopusID: 2-s2.0-15044350805OAI: oai:DiVA.org:kth-5486DiVA: diva2:9869
QC 201009012006-03-152006-03-152010-12-07Bibliographically approved