Abstract: We have investigated linear as well as nonlinear propagation e?ects on a relatively weak
ultrashort pulse arising from coherent nuclear motion. To this end, we have developed ana-
lytical and numerical models used to calculate the molecular response to a strong, ultrashort
pump pulse, and propagate a weak probe pulse in the presence of the nuclear wave packet.
The molecular response is described in terms of an ”e?ective” susceptibility, which can be
split into linear and nonlinear contributions. While a lot of what is discussed in terms of
propagation e?ects is applicable to both rotational and vibrational wave packets, molecular
alignment, i.e., coherent rotational motion of linear molecules, is where the focus lies. We
have applied spectral interferometry to detecting molecular alignment, both in scanning and
single-shot con?gurations, to observe propagation e?ects due to the e?ective linear suscepti-
bility and carried out calculations and measurements showing the dependence of the e?ective third-order susceptibility on coherent nuclear motion. Lastly, a strongly enhanced conversion e?ciency to the third harmonic from a relatively weak probe pulse is observed in a variety
of molecular and atomic gases.

Adviser: Randy Bartels
Co-Adviser: none
Non-ECE Member: Siu-Au Lee
Member 3: Carmen Menoni
Addional Members: none

Publications:

Program of Study: