Control of light polarization using spin-injected opto-electronic devices with vertical geometries

International audienceIn the past decade, a continous interest and a research effort have been dedicated to the study of spin injection into Semiconductor-based Light Emitting Device such as Spin-Light Emitting Diodes (Spin-LEDs) [1,2] and more recently Spin-LASERs such as Vertical Cavity Surface Emitting LASERs (VCSELs) [3]. We will first focus on structural characterization and optical polarization efficiency of Ta/CoFeB/MgO spin injector grown on the top of an InGaAs-QW LED. We will show that for very thin layer of CoFeB it is possible to induce Perpendicular Magnetic Anisotropy leading to emission of polarized light at remanence (i.e. without external magnetic field). A natural extension of this magnetic bit conversion into circularly-polarized light via spin-polarized current is to extend the Spin-LED principle to Spin-LASER. Based on our expertise on Spin-LEDs, we fabricated and characterized an optically pumped (100)-oriented InGaAs/GaAsP MQW Vertical External Cavity Surface Emitting Laser (VECSEL). Using an optical spin injection we were able to demonstrate a switching between two highly circular polarization states [4]. We will discuss the condition for the control of the electromagnetic field polarization. Acknowledgment: This work has been partially financed by the “Agence Nationale de la Recherche” (INSPIRE Project), the french network RENATECH and the ANR-NSFC (SISTER Project). References: [1] R. Fiederling et al., Nature 402, 787 (1999) [2] V.F. Motsnyi et al., APL 81, 265 (2002) [3] I. Zutic et al., “Semiconductor spin-lasers”, Handbook of Spin Transport and Magnetism, (CRC Press, 2011), Chap. 38, pp. 731–745. [4] J. Frougier et al., APL 103 252402 (2013)