All-Electronic Phase-Resolved THz Microscopy Using the Self-Mixing Effect in a Semiconductor Laser

We report all-electronic coherent scattering-type scanning near-field microscopy (s-SNOM) using a terahertz-frequency quantum cascade laser. By exploiting the self-mixing effect in these lasers, conjunction with electronic frequency tuning of laser, we demonstrate spatial mapping both amplitude and phase scattered field deeply subwavelength resolution. apply our technique for phonon-resonant crystal. The extracted parameters reveal clear contrast when compared to metallic nonresonant dielectric materials show excellent agreement those calculated finite-dipole model interaction between s-SNOM tip resonant sample Reststrahlen band. Our paves way fast nanoscale-resolved function solid state systems optoelectronic nanodevices at terahertz frequencies.