@article{reichel_pogna_biasco_viti_di gaspare_beere_ritchie_vitiello_2021, 
  title={Self-mixing interferometry and near-field nanoscopy in quantum cascade random lasers at terahertz frequencies}, 
  volume={10}, 
  DOI={10.1515/nanoph-2020-0609}, 
  abstractNote={<jats:title>Abstract</jats:title>
               <jats:p>We demonstrate that electrically pumped random laser resonators, operating at terahertz (THz) frequencies, and comprising a quantum cascade laser heterostructure, can operate as sensitive photodetectors through the self-mixing effect. We devise two-dimensional cavities exploiting a disordered arrangement of surface holes that simultaneously provide optical feedback and allow light out-coupling. By reflecting the emitted light back onto the surface with random holes pattern, and by varying the external cavity length, we capture the temporal dependence of the laser voltage, collecting a rich sequence of interference fringes that follow the bias-dependent spectral emission of the laser structure. This provides a visible signature of the random laser sensitivity to the self-mixing effect, under different feedback regimes. The latter effect is then exploited, in the near-field, to demonstrate detectorless scattering near-field optical microscopy with nanoscale (120 nm) spatial resolution. The achieved results open up possibilities of detectorless speckle-free nano-imaging and quantum sensing applications across the far-infrared.</jats:p>}, 
  publisher={Walter de Gruyter GmbH}, 
  author={Reichel, Kimberly S. and Pogna, Eva Arianna Aurelia and Biasco, Simone and Viti, Leonardo and Di Gaspare, Alessandra and Beere, Harvey E. and Ritchie, David A. and Vitiello, Miriam S.}, 
  year={2021}, 
  month={Mar}
  }