Uniaxial stress flips the natural quantization axis of a quantum dot for integrated quantum photonics

TL;DR

Applying uniaxial stress to gallium arsenide quantum dots can reorient their quantization axis into the plane, enabling better integration with planar photonic circuits by controlling optical selection rules and transition dipole orientations.

Contribution

Demonstrated that moderate in-plane uniaxial stress can flip the quantization axis of quantum dots into the growth plane, improving their suitability for integrated quantum photonics.

Findings

Uniaxial stress reorients the quantization axis into the plane.

Strain influences excitonic fine-structure and selection rules.

Potential for enhanced quantum light sources with controlled dipole orientation.

Abstract

The optical selection rules in epitaxial quantum dots are strongly influenced by the orientation of their natural quantization axis, which is usually parallel to the growth direction. This configuration is well suited for vertically emitting devices, but not for planar photonic circuits because of the poorly controlled orientation of the transition dipoles in the growth plane. Here we show that the quantization axis of gallium arsenide dots can be flipped into the growth plane via moderate in plane uniaxial stress. By using piezoelectric strain actuators featuring strain-amplification we study the evolution of the selection rules and excitonic fine-structure in a regime, in which quantum confinement can be regarded as a perturbation compared to strain in determining the symmetry properties of the system. The experimental and computational results suggest that uniaxial stress, may be the right tool to obtain quantum light sources with ideally oriented transition dipoles and enhanced oscillator strengths for integrated quantum photonics.