Terahertz quantum cascade lasers with thin resonant-phonon depopulation active regions and surface-plasmon waveguides

TL;DR

This paper presents terahertz quantum cascade lasers with thin active regions and surface-plasmon waveguides, demonstrating optimized device performance through varying active region thicknesses for improved efficiency and reduced heating.

Contribution

The study introduces a three-well resonant-phonon depopulation design with surface-plasmon waveguides and analyzes the impact of different active region thicknesses on device performance.

Findings

7.5 μm active region thickness yields lowest electrical power density at threshold.

Thinner active regions are easier to grow and reduce device heating.

Optimal trade-off found at 7.5 μm thickness for device efficiency.

Abstract

We report three-well, resonant-phonon depopulation terahertz quantum cascade lasers with semi-insulating surface-plasmon waveguides and reduced active region (AR) thicknesses. Devices with thicknesses of 10, 7.5, 6, and 5 {\mu}m are compared in terms of threshold current density, maximum operating temperature, output power and AR temperature. Thinner ARs are technologically less demanding for epitaxial growth and result in reduced electrical heating of devices. However, it is found that 7.5-{\mu}m-thick devices give the lowest electrical power densities at threshold, as they represent the optimal trade-off between low electrical resistance and low threshold gain.