Terahertz gas spectroscopy through self-mixing in a quantum-cascade laser

We demonstrate the feasibility of high-resolution terahertz gasspectroscopy based on the externaloptical feedback effect in a quantum-cascade laser. Tuning the frequency of the quantum-cascade laser across a molecularabsorption line of CH3OH leads to a reduction of theoptical feedback, which can be detected by monitoring the voltage across the quantum-cascade laser. This method provides a highspectral resolution ofν/Δν=106 and a sensitivity comparable to that obtained with a cryogenically cooled Ge:Ga photoconductive detector.

Source: Applied Physics Letters - November 7, 2016 Category: Physics Authors: T. Hagelschuer, M. Wienold, H. Richter, L. Schrottke, K. Biermann, H. T. Grahn and H.-W. H übers Source Type: research