Emulating a broadband frequency sweep for Terahertz thin-film imaging

Conventional continuous-wave Terahertz imaging and thickness resolution systems often rely on the Fabry-Pérot resonances generated in the sample being imaged. As the samples become thinner, larger frequency sweeps are necessary for their visualisation. In this work, we demonstrate a post-processing technique employing zero-padding of a smaller frequency sweep between frequency intervals as low as 10 GHz up to intervals of 200 GHz, conducted between 0.6-0.8 THz, to emulate the thickness resolution generally achieved by orders of magnitude larger frequency ranges.