Efficient Room‐Temperature Voltage Control of Picosecond Optical Spin Orientation Using a III‐V Semiconductor Nanostructure.

Manipulation of the optical spin orientation in semiconductors is a key technology for realizing spin‐based photoelectric information processing. Application of magnetic field is a simple method to control the spin polarization degree through Zeeman splitting. However, this effect can only be achieved at cryogenic temperatures and in a strong magnetic field. Here, room‐temperature voltage control of optical polarization in the range of 3–15%, corresponding to a 12–60% change in relative spin polarization is demonstrated. For this, a III‐V semiconductor quantum dot tunnel coupled with a quantum well spin reservoir is used. The spin‐flip scattering rate within quantum dots is electric‐field‐controlled in the time domain of several tens of picoseconds. This is achieved by precise control of the tunnel injection efficiency of electrons and holes via coupled potential modification. The findings will pave the way for the generation of ultrafast spin‐modulated optical signals by the electric field effect. [ABSTRACT FROM AUTHOR]