The influence of a single quantum dot state on the characteristics of a microdisk laser

TL;DR

This paper demonstrates a quantum dot microcavity laser with ultra-low threshold, showing that aligning a single quantum dot state with the cavity mode significantly reduces the lasing threshold and affects cavity mode behavior.

Contribution

It reveals the impact of a single quantum dot state on the lasing characteristics and threshold in a microdisk laser, highlighting the role of quantum dot-cavity resonance.

Findings

Lasing threshold drops to sub-microwatt levels when a QD state is resonant.

Cavity quality factor exceeds 15,000 before lasing occurs.

Cavity mode initially degrades with pump power when no QD states are resonant.

Abstract

We report a quantum dot microcavity laser with a cw sub-microwatt lasing threshold, where a significant reduction of the lasing threshold is observed when a single quantum dot (QD) state is aligned with a cavity mode. The quality factor exceeds 15 000 before the system lases. When no QD states are resonant, below threshold the cavity mode initially degrades with increasing pump power, after which saturation occurs and then the cavity mode recovers. We associate the initial cavity mode spoiling with QD state broadening that occurs with increasing pump power.