title: Near-field terahertz probes with room-temperature nanodetectors for subwavelength resolution imaging.
abstract: Near-field imaging with terahertz (THz) waves is emerging as a powerful technique for fundamental research in photonics and across physical and life sciences. Spatial resolution beyond the diffraction limit can be achieved by collecting THz waves from an object through a small aperture placed in the near-field. However, light transmission through a sub-wavelength size aperture is fundamentally limited by the wave nature of light. Here, we conceive a novel architecture that exploits inherently strong evanescent THz field arising within the aperture to mitigate the problem of vanishing transmission. The sub-wavelength aperture is originally coupled to asymmetric electrodes, which activate the thermo-electric THz detection mechanism in a transistor channel made of flakes of black-phosphorus or InAs nanowires. The proposed novel THz near-field probes enable room-temperature sub-wavelength resolution coherent imaging with a 3.4 THz quantum cascade laser, paving the way to compact and versatile THz imaging systems and promising to bridge the gap in spatial resolution from the nanoscale to the diffraction limit.
authors.affiliation: University College London, Electronic and Electrical Engineering, London, WC1E 7JE, UK.
authors.forename: Oleg
authors.initials: O
authors.lastname: Mitrofanov
authors.affiliation: NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, Italy.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Viti
authors.affiliation: NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Dardanis
authors.affiliation: NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, Italy.
authors.forename: Maria Caterina
authors.initials: MC
authors.lastname: Giordano
authors.affiliation: NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Ercolani
authors.affiliation: Università degli Studi della Calabria, Dipartimento di Fisica, via Ponte Bucci, 87036 Rende (CS), Italy.
authors.forename: Antonio
authors.initials: A
authors.lastname: Politano
authors.affiliation: NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, Italy.
authors.forename: Lucia
authors.initials: L
authors.lastname: Sorba
authors.affiliation: NEST, Istituto Nanoscienze - CNR and Scuola Normale Superiore, Piazza San Silvestro 12, Pisa, 56127, Italy.
authors.forename: Miriam S
authors.initials: MS
authors.lastname: Vitiello