Analysis of dual-section DFB-QCLs for spectroscopic applications

Abstract

We investigate the functionalities of dual-section (DS) distributed feedback (DFB) quantum cascade lasers (QCLs) in continuous wave (CW) and intermittent continuous wave (iCW) operation. We analyze internal etaloning with spectrally resolved light-current-voltage characterization, time-resolved spectral analysis of thermal chirping during iCW operation. The experimental analysis is accompanied by a combination of finite element method (FEM) simulations and transfer matrix method (TMM) calculations of DS-DFB structures. Finally, we demonstrate how the internal etaloning can be minimized by means of anti-reflective (AR) coatings and how spectroscopic data with state-of-the-art precision can be acquired with such lasers.