Light-hole transitions in quantum dots: Realizing full control by highly focused optical-vortex beams
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 may carry well-defined values of spin (polarization σ) and orbital angular momenta; the or...
| Authors: | , |
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| Format: | article |
| Status: | Published version |
| Publication Date: | 2014 |
| Country: | Argentina |
| Institution: | Consejo Nacional de Investigaciones Científicas y Técnicas |
| Repository: | CONICET Digital (CONICET) |
| Language: | English |
| OAI Identifier: | oai:ri.conicet.gov.ar:11336/18032 |
| Online Access: | http://hdl.handle.net/11336/18032 |
| Access Level: | Open access |
| Keyword: | Optical Vortex Twisted Light Quantum Dot https://purl.org/becyt/ford/1.3 https://purl.org/becyt/ford/1 |
| Summary: | 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 may carry well-defined values of spin (polarization σ) and orbital angular momenta; the orbital angular momentum per photon is given by the topological charge 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 = 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 σ and . When sgn(σ) = sgn(), the pulse will create electron-hole pairs with band+spin and envelope angular momenta both equal to 1. In contrast, for sgn(σ) = sgn(), 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 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. |
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