Improved comb and dual-comb operation of terahertz quantum cascade lasers utilizing a symmetric thermal dissipation

TL;DR

This paper demonstrates that using symmetric thermal dissipation in terahertz quantum cascade lasers improves their frequency comb and dual-comb performance, verified through thermal modeling and experimental measurements, enhancing their application potential.

Contribution

The study introduces a symmetric thermal dissipation scheme for terahertz QCLs, significantly enhancing comb operation compared to traditional asymmetric schemes.

Findings

Symmetric thermal dissipation results in more uniform thermal conduction.

Lower maximum temperature in the active region improves laser performance.

Enhanced comb and dual-comb operation verified experimentally.

Abstract

In the terahertz frequency range, the quantum cascade laser (QCL) is a suitable platform for the frequency comb and dual-comb operation. Improved comb performances have been always much in demand. In this work, by employing a symmetric thermal dissipation scheme, we report an improved frequency comb and dual-comb operation of terahertz QCLs. Two configurations of cold fingers, i.e., type A and B with asymmetric and symmetric thermal dissipation schemes, respectively, are investigated here. A finite-element thermal analysis is carried out to study the parametric effects on the thermal management of the terahertz QCL. The modeling reveals that the symmetric thermal dissipation (type B) results in a more uniform thermal conduction and lower maximum temperature in the active region of the laser, compared to the traditional asymmetric thermal dissipation scheme (type A). To verify the simulation, experiments are further performed by measuring laser performance and comb characteristics of terahertz QCLs emitting around 4.2 THz mounted on type A and type B cold fingers. The experimental results show that the symmetric thermal dissipation approach (type B) is effective for improving the comb and dual-comb operation of terahertz QCLs, which can be further widely adopted for spectroscopy, imaging, and near-field applications.