Strong Optical Field Ionization of Solids
Population transfer from the valence to conduction band in the presence of an intense laser field is explored theoretically in semiconductors and dielectrics. Experiments on intense laser driven dielectrics have revealed population transfer to the conduction band that differs from that seen in se...
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| Language: | en |
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Université d'Ottawa / University of Ottawa
2018
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| Online Access: | http://hdl.handle.net/10393/37151 http://dx.doi.org/10.20381/ruor-21423 |
| Summary: | Population transfer from the valence to conduction band in the presence of
an intense laser field is explored theoretically in semiconductors and dielectrics.
Experiments on intense laser driven dielectrics have revealed population transfer
to the conduction band that differs from that seen in semiconductors. Our
research explores two aspects of ionization in solids. (i) Current ionization
theories neglect coupling between valence and conduction band and therewith
the dynamic Stark shift. Our single-particle analysis identifies this as a potential
reason for the different ionization behaviour. The dynamic Stark shift increases
the bandgap with increasing laser intensities thus suppressing ionization to an
extent where virtual population oscillation become dominant. The dynamic
Stark shift plays a role dominantly in dielectrics which due to the large bandgap
can be exposed to significantly higher laser intensities. (ii) In the presence
of laser dressed virtual population of the conduction band, elastic collisions
potentially transmute virtual into real population resulting in ionization. This
process is explored in context of relaxation time approximation. |
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