CONICET | Buscador de Institutos y Recursos Humanos

We theoretically investigate the response of bulk semiconductors to excitation by plane waves and twist light below the energy bandgap. To do its we modify the generalized assumption, known as ?vertical transitions?(VT), that neglects the photon?s momentum in direct absorption/emission processes. Exceptions are found in early and recent works, reporting theoretical and experimental results strongly dependending on the conservation of the linear momentum of the photon that results in new selection rules not accounted for by VT. The susceptibility shows the expected features, i.e. no spatial dependence but ?spatial dispersion?(dependence). The COM-motion correction introduces a tiny shift in the absorption line. Used in conjunction with Maxwell?sequations, the susceptibility yields information about the effect that electrons has on the EM field, eg. attenuation of the beam.