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Regular version of the site

Article

Dynamics of Broadband Lasing Cascade from a Single Dot-in-well InGaAs Microdisk

Scientific Reports. 2019. Vol. 9. No. 1. P. 5635.

The development of a fast semiconductor laser is required for the realization of next-generation
telecommunication applications. Since lasers operating on quantum dot ground state transitions
exhibit only limited gain due to the saturation effect, we investigate lasing from excited states and
compare its corresponding static and dynamic behavior to the one from the ground state. InAs quantum
dots (QDs) grown in dot-in-well (DWELL) structures allowed to obtain light emission from ground and
three excited states in a spectral range of 1.0–1.3 μm. This emission was coupled to whispering gallery
modes (WGMs) of a 6 μm microdisk resonator and studied at room temperature by steady-state and
time-resolved micro-photoluminescence. We demonstrate a cascade development of lasing arising
from the ladder of quantum dot states, and compare the lasing behavior of ground and excited state
emission. While the lasing threshold is being increased from the ground state to the highest excited
state, the dynamic behavior is improved: turn-on times and lifetimes of WGMs become shorter paving
the way towards high frequency direct driven microlasers.