Temperature dependence of the gain profile for THz quantum cascade lasers

TL;DR

This paper investigates how the peak gain of resonant-phonon THz quantum cascade lasers diminishes with rising temperature, highlighting impurity scattering as the main cause rather than population inversion loss.

Contribution

It provides a detailed analysis of microscopic scattering processes affecting the gain profile in THz QCLs as temperature increases.

Findings

Impurity scattering causes increased broadening of the gain profile.

Peak gain decreases rapidly with temperature due to scattering effects.

Population inversion remains relatively stable despite gain reduction.

Abstract

We study the rapid decrease of peak gain in resonant-phonon THz Quantum Cascade Lasers with increasing temperature. The effect of various microscopic scattering processes on the gain profile as a function of temperature is discussed. We argue that increased broadening, primarily due to increased impurity scattering, and not diminishing population inversion, is the main reason for the reduction of peak gain.