Tuning terahertz transitions in a double-gated quantum ring

TL;DR

This paper explores how a double-gated quantum ring can be tuned to control terahertz inter-level transitions, enabling polarization-dependent optical properties useful for three-level lasing applications.

Contribution

It introduces a theoretical model showing how gate voltages influence THz transitions and selection rules in a quantum ring, differing from traditional double well systems.

Findings

Gate voltages significantly alter inter-level spacings in the THz range.

Polarization angle affects dipole transition selection rules.

Quantum ring geometry enables polarization-dependent transitions for lasing.

Abstract

We theoretically investigate the optical functionality of a semiconducting quantum ring manipulated by two electrostatic lateral gates used to induce a double quantum well along the ring. The well parameters and corresponding inter-level spacings, which lie in the THz range, are highly sensitive to the gate voltages. Our analysis shows that selection rules for inter-level dipole transitions, caused by linearly polarized excitations, depend on the polarization angle with respect to the gates. In striking difference from the conventional symmetric double well potential, the ring geometry permits polarization-dependent transitions between the ground and second excited states, allowing the use of this structure in a three-level lasing scheme.