Optical limiting and pulse reshaping of picosecond pulse trains by fullerene C60
2009 (English)In: Journal of Electron Spectroscopy and Related Phenomena, ISSN 0368-2048, Vol. 174, 125-130 p.Article in journal (Refereed) Published
We present a dynamical theory of nonlinear absorption and propagation of a laser pulse train that contains 20 subpulses with an individual pulse width of loops. It is shown that the accumulative nonlinearity and the reverse saturation absorption play important roles in the optical limiting performance and pulse shaping. When the incident field is not too strong, the population transfer reveals a slow response process, and the periodic sequence of short light pulses can be regarded as a continuous long pulse. The general theory is applied to fullerence C-60, which is a popular reverse saturable absorption material and a good limiter because of its larger excited-state absorption cross-section compared with that of the ground state. The propagation of the front subpulses is mainly affected by the linear transition between the ground state and the first excited singlet state, while the latter subpulses are attenuated by the excited-state absorption. Moreover, these two different kinds of absorption mechanisms result in different radial distributions for different subpulses. The pulse propagation is studied by solving numerically the coupled rate equations and the propagation equation of the optical pulse intensity, using experimental parameters as input. We suggest a new method to measure the lifetime of the triplet state.
Place, publisher, year, edition, pages
2009. Vol. 174, 125-130 p.
Pulse trains; Optical limiting; Fullerence; Singlet-triplet
IdentifiersURN: urn:nbn:se:kth:diva-11435DOI: 10.1016/j.elspec.2009.03.010ISI: 000271347700021ScopusID: 2-s2.0-70349209130OAI: oai:DiVA.org:kth-11435DiVA: diva2:276058
QC 201007132009-11-102009-11-102010-12-07Bibliographically approved