Optically reconfigurable polarized emission in Germanium

TL;DR

This paper demonstrates the dynamic control of light polarization in germanium using optical pumping, enabling reconfigurable polarized emission at telecom wavelengths without magnetic fields, advancing spin-optoelectronic applications.

Contribution

It introduces a method to manipulate light chirality in germanium through optical pumping, leveraging its multivalley conduction band, without magnetic or phase control.

Findings

Polarization can be swept through orthogonal states.

Control achieved without magnetic fields.

Potential for spin-enhanced optoelectronic devices.

Abstract

Light polarization can conveniently encode information. Yet, the ability to steer polarized optical fields is notably demanding but crucial to develop practical methods for data encryption and to gather fundamental insights into light-matter interactions. Here we demonstrate the dynamic manipulation of the chirality of light in the telecom wavelength regime. This unique possibility is enrooted in the multivalley nature of the conduction band of a conventional semiconductor, namely Ge. In particular, we demonstrate that optical pumping suffices to govern the kinetics of spin-polarized carriers and eventually the chirality of the radiative recombination. We found that the polarization of the optical transitions can be remarkably swept through orthogonal eigenstates without magnetic field control or phase shifter coupling. Our results anticipate spin-enhanced optoelectronic functionalities in materials backed by the mainstream microelectronics industry and provide guiding information for the selection and design of functionalized emitters based on novel group IV compounds.