Quantum-Dot Cascade Laser: Proposal for an Ultra-Low-Threshold Semiconductor Laser

TL;DR

This paper proposes a quantum-dot cascade laser design that significantly reduces threshold current by eliminating phonon decays, using feasible nanostructure fabrication techniques.

Contribution

It introduces a quantum-dot version of the cascade laser, achieving lower thresholds through three-dimensional confinement and practical fabrication parameters.

Findings

Order-of-magnitude reduction in threshold current.

Feasible dot size and density requirements.

Potential for practical implementation with current technology.

Abstract

We propose a quantum-dot version of the quantum-well cascade laser of Faist et al. [Science {\bf 264}, 553 (1994)]. The elimination of single phonon decays by the three-dimensional confinement implies a several order-of-magnitude reduction in the threshold current. The requirements on dot size (10-20nm) and on dot density and uniformity [one coupled pair of dots per (180nm)^3 with 5% nonuniformity] are close to current technology.