Credit: Lars Lüder, Empa
This is how the IR spectrometer works: The photodetector, fabricated on top of a surface optical waveguide, consists of a bottom gold electrode at the bottom functioning as a scattering center, a photoactive layer (consisting of colloidal mercury telluride – HgTe – quantum dots), and a top gold electrode. By moving the mirror, the measured photocurrent maps the light intensity of the standing wave. i.e. the IR light. A Fourier transformation of the measured signal gives the optical spectra.