Swapping of orbital angular momentum states of light in a quantum well waveguide
School of Physics, Iran University of Science and Technology, 1684613114, Tehran, Iran
2 Institute of Theoretical Physics and Astronomy, Vilnius University, Saulėtekio 3, 10257, Vilnius, Lithuania
3 Materials Science Department, School of Natural Sciences, University of Patras, 265 04, Patras, Greece
Accepted: 19 April 2021
Published online: 27 April 2021
We study the effect of orbital angular momentum transfer between optical fields in a semiconductor quantum well waveguide with four energy levels in a closed-loop configuration via four-wave mixing. The waveguide is driven by two strong control fields and two weak probe fields. We consider three different cases for the light-matter interaction in order to efficiently exchange optical vortices. In the first two cases, the system is initially prepared in either a lower electromagnetically induced transparency or a coherent population trapping state, while the last case prepares the system in an upper state, enabling to induce the electron spin coherence. We find that for appropriate parameters and via the spin coherence effect, the efficiency of four-wave mixing is much higher in the quantum well waveguide. Working in the electron spin coherence regime, we then study the light-matter interaction under the situation where only one of the control fields has an optical vortex. The orbital angular momentum of the vortex control beam can be efficiently transferred to a generated probe field via the spin coherence. We also show that the spatially dependent optical effects of the waveguide can be strongly modified by the electron spin coherence.
© The Author(s), under exclusive licence to Società Italiana di Fisica and Springer-Verlag GmbH Germany, part of Springer Nature 2021