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Light-hole transitions in quantum dots: realizing full control by highly focused optical-vortex beams
- Source :
- Phys. Rev. B 90, 115401 (2014)
- Publication Year :
- 2014
-
Abstract
- An optical-vortex is an inhomogeneous light beam having a phase singularity at its axis, where the intensity of the electric and/or magnetic field may vanish. Already well studied are the paraxial beams, which are known to carry well defined values of spin (polarization $\sigma$) and orbital angular momenta; the orbital angular momentum per photon is given by the topological charge $\ell$ times the Planck constant. Here we study the light-hole--to--conduction band transitions in a semiconductor quantum dot induced by a highly-focused beam originating from a $\ell=1$ paraxial optical vortex. We find that at normal incidence the pulse will produce two distinct types of electron--hole pairs, depending on the relative signs of $\sigma$ and $\ell$. When sign($\sigma$)$=$sign($\ell$), the pulse will create electron--hole pairs with band+spin and envelope angular momenta both equal to one. In contrast, for sign($\sigma$)$\neq$sign($\ell$), the electron-hole pairs will have neither band+spin nor envelope angular momenta. A tightly-focused optical-vortex beam thus makes possible the creation of pairs that cannot be produced with plane waves at normal incidence. With the addition of co-propagating plane waves or switching techniques to change the charge $\ell$ both the band+spin and the envelope angular momenta of the pair wave-function can be precisely controlled. We discuss possible applications in the field of spintronics that open up.
- Subjects :
- Condensed Matter - Mesoscale and Nanoscale Physics
Subjects
Details
- Database :
- arXiv
- Journal :
- Phys. Rev. B 90, 115401 (2014)
- Publication Type :
- Report
- Accession number :
- edsarx.1403.7229
- Document Type :
- Working Paper
- Full Text :
- https://doi.org/10.1103/PhysRevB.90.115401