A systematic shift in spectral emission wavenumbers in quantum cascade lasers (QCLs) is observed over a variation in cavity lengths from 0.5 to 3 mm resulting in a gain peak shift ranging from 2404 to 2286 cm -1. Thereby, a wavelength selection range of 118 cm-1 is provided, which is sufficiently broad for selecting the laser emission across the entire CO 2absorption band at 2326 cm -1 (4.3 μm). In contrast to current QCL wavelength selection techniques, modifying the cavity length is a straightforward postprocessing procedure. Experimental evidence confirms that this frequency shift is due to a change in threshold voltage and applied electric field as a function of cavity length which is in agreement with the theory.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)