Fourier-transform infrared spectroscopy
The Fourier-transform infrared spectroscopy is used for investigations of predominantly terahertz and mid-infrared GaAs-based quantum-cascade lasers (QCLs). We focus on studies of the laser performance for different QCL designs including the doping concentration and the waveguide structure, the driving current, and the operating temperature. In particular, effects of coupled multi-sections in QCLs on the laser modes are investigated. Furthermore, intersubband transitions, free-carrier and plasmon excitations, phonons and polaritons in GaAs, Ga(As,N), and GaN-based nanostructures grown in the institute have been studied.
Specifications of the Bruker IFS 66v
Specifications of the Bruker IFS 120HR
Example:

Suppression of longitudinal modes of two-sectioned, coupled-cavity THz QCLs (TSCC) with a total length of the laser ridge of 5 mm for different ratios of the length of the two subcavities L2/L1 as indicated. Due to interference effects in the TSCC QCL, the mode spacing Δν is determined by L1+L2, whereas the number of suppressed modes (mode spacing between major modes Δνmaj) is determined by the ratio L2/L1.

