QCL active region overheat in pulsed mode: effects of non-equilibrium heat dissipation on laser performance

TL;DR

This paper investigates how non-equilibrium heat dissipation affects quantum cascade laser performance, emphasizing the limitations imposed by alloy compositions and the importance of structural features in pulsed and continuous operation modes.

Contribution

It introduces a heat equation approach to analyze non-equilibrium temperature effects in QCLs, highlighting the impact of alloy structures on thermal management.

Findings

Alloy compositions limit heat dissipation in QCLs.

Post-growth modifications influence thermal properties mainly in CW mode.

Non-equilibrium temperature distribution significantly affects pulsed laser performance.

Abstract

Quantum cascade lasers are of high interest in the scientific community due to unique applications utilizing the emission in mid-IR range. The possible designs of QCL are quite limited and require careful engineering to overcome some crucial disadvantages. One of them is an active region (ARn) overheat, that significantly affects the laser characteristics in the pulsed operation mode. In this work we consider the effects related to the non-equilibrium temperature distribution, when thermal resistance formalism is irrelevant. We employ the heat equation and discuss the possible limitations and structural features stemming from the chemical composition of the AR. We show that the presence of alloys in the ARn structure fundamentally limits the heat dissipation in pulsed and CW regimes due to their low thermal conductivity. Also the QCL post-growths affects the thermal properties of a device only in (near)CW mode while it is absolutely invaluable in the pulsed mode