Brandstetter Martin, Schönhuber Sebastian, Krall Michael, Kainz Martin A, Detz Hermann, Zederbauer Tobias, Andrews Aaron M, Strasser Gottfried, Unterrainer Karl
Opt Express. 2016 Oct 31;24(22):25462-25470. doi: 10.1364/OE.24.025462.
We demonstrate a convenient and fast method to measure the spectrally resolved far-fields of multimode terahertz quantum cascade lasers by combining a microbolometer focal plane array with an FTIR spectrometer. Far-fields of fundamental TM0 and higher lateral order TM1 modes of multimode Fabry-Pérot type lasers have been distinguished, which very well fit to the results obtained by a 3D finite-element simulation. Furthermore, multimode random laser cavities have been investigated, analyzing the contribution of each single laser mode to the total far-field. The presented method is thus an important tool to gain in-depth knowledge of the emission properties of multimode laser cavities at terahertz frequencies, which become increasingly important for future sensing applications.
