Below-bandgap excitation of bulk semiconductors by twisted light
Departamento de Física “J. J. Giambiagi”, Universidad de Buenos Aires Ciudad Universitaria, Pabellón I, C1428EGA Ciudad de Buenos Aires, Argentina and Consejo Nacional de Investigaciones Científicas y Técnicas - Argentina
Accepted: 12 July 2010
I theoretically investigate the excitation of bulk semiconductors by twisted light below the energy bandgap. To this end, I modify a well-known model of light-semiconductor interaction to account for the conservation of the momentum of light. I predict that the optical excitation produces a superposition of exciton-like states that undergo a complex center-of-mass motion. In addition, I show that the energy at which the absorption occurs is slightly different from that of pure excitons, due to the center-of-mass kinetic energy of the new states. Finally, I provide expressions for the induced polarization and electric current, which exhibit complex spatial patterns that mimic the twisted-light electric field.
PACS: 78.20.Bh – Theory, models, and numerical simulation / 78.40.Fy – Semiconductors / 71.35.-y – Excitons and related phenomena
© EPLA, 2010