Breakdown of dipole approximation and its effect on high harmonic generation
- 226 Downloads
Here, we present a study of high-harmonic-generation using the model system of polyacetylene when irradiated with intense laser-field. The system is prepared in a time-periodic Floquet-state. Only odd-order harmonics are obtained within dipole approximation due to the dynamical-symmetry of the Floquet-state. However, odd as well as even-order harmonics are obtained in case of beyond-dipole approximation. Dipole approximation is expected to be valid when the electron during oscillation is confined to a very small region compared to the wavelength of light. However, it is found that the dipole approximation breaks down even if the electron remains delocalised over a region less than 1 nm.
KeywordsUltraintense and Ultra-short Laser Fields
- 27.R. Saito, G. Dresselhaus, M.S. Dresselhaus, Physical Properties of Carbon Nanotubes (Imperial College Press, London, 1998)Google Scholar