TY  - GEN
TI  - Sub-wavelength near field imaging techniques at terahertz frequencies
EP  - 15
AV  - public
Y1  - 2018/01/26/
N1  - This version is the version of record. For information on re-use, please refer to the publisher?s terms and conditions.
ID  - discovery10060151
N2  - Near-field imaging techniques at terahertz (THz) frequencies are severely restricted by diffraction. To date, different detection schemes have been developed, based either on sub-wavelength metallic apertures or on sharp metallic tips. However high-resolution THz imaging, so far, has been relying predominantly on detection techniques that require either an ultrafast laser or a cryogenically-cooled THz detector, at the expenses of a lack of sensitivity when high resolution levels are needed. Here, we demonstrate two novel near-field THz imaging techniques able to combine strongly sub-wavelength spatial resolution with highly sensitive amplitude and phase detection capability. The first technique exploits an interferometric optical setup based on a THz quantum cascade laser (QCL) and on a near-field probe nanodetector, operating at room temperature. By performing phase-sensitive imaging of THz intensity patterns we demonstrate the potential of our novel architecture for coherent imaging with sub-wavelength spatial resolution improved up to 17 ?m. The second technique is a detector-less s-SNOM system, exploiting a THz QCL as source and detector simultaneously. This approach enables amplitude- and phase-sensitive imaging by self-mixing interferometry with spatial resolution of 60-70 nm.
SN  - 0277-786X
PB  - SPIE
UR  - https://doi.org/10.1117/12.2291518
CY  - Bellingham (WA), USA
KW  - Terahertz radiation
KW  -  Near field
KW  -  Near field optics
KW  -  Quantum cascade lasers
KW  -  Signal detection
KW  -  Sensors
KW  -  Spatial resolution
A1  - Giordano, MC
A1  - Viti, L
A1  - Mitrofanov, O
A1  - Scamarcio, G
A1  - Mastel, S
A1  - Hillenbrand, R
A1  - Ercolani, D
A1  - Sorba, L
A1  - Vitiello, MS
T3  - SPIE OPTO
ER  -