Abstract
We demonstrate coherent three-dimensional terahertz imaging by frequency modulation of a quantum cascade laser in a compact and experimentally simple self-mixing scheme. Through this approach, we can realize significantly faster acquisition rates compared to previous schemes employing longitudinal mechanical scanning of a sample. We achieve a depth resolution of better than 0.1 mu m with a power noise spectral density below -50 dB/Hz, for a sampling time of 10 ms/pixel. (C) 2015 Optical Society of America