Compressed sensing with near-field THz radiation

Exploiting Total Internal Reflection Geometry for Terahertz Devices and Enhanced Sample Characterization

“…An easy way of creating a THz‐spatial modulator, using commercially available equipment, is to spatially pattern a visible light beam with a digital micromirror device (DMD) and project this onto a semiconductor. This has been demonstrated in our previous work . We found that the spatial light modulation techniques grant about ten times higher SNR for the same measurement time.…”

“…Figure b shows a 32 × 32 image of a Gaussian beam acquired in 1s, with a DMD switch rate of 1 kHz and 1024 masks projected. This was orders faster than our previous works which took hours . However, the SNR of the image was relatively low because the lock‐in amplifier normally applied in a THz‐TDS system was removed to enable a fast switching rate.…”

“…As shown in ref. , when the device is working under a 68° incident angle, we can obtain a mask with positive and negative values from a single measurement without any lock‐in subtraction detection schemes, unlike in previous work . The proposed graphene device is just a broadband and offers modulation depths close to 100% with potential switch rates in the MHz range with the correct electrical design.…”

Polarization-Independent Tunable Ultra-Wideband Meta-Absorber in Terahertz Regime

“…The terahertz (THz) range of the electromagnetic spectrum, located between microwave and infrared band, has received fast growing research interest in the past two decades, due to extensive applications such as safety inspection, imaging, sensing, material detection, secure communication and so on in virtue of its unique properties [1][2][3][4][5]. The THz absorbing structure has been part of important elements in these THz applications.…”

Phase-sensitive terahertz imaging using room-temperature near-field nanodetectors

“…The spectrum of THz near-field imaging applications is growing and it includes nanoscale mapping of plasmons in emerging bi-dimensional (2D) atomic materials (topological insulators [10], phosphorene [3], silicene [11], and their combined van der Waals heterostructures [12]), fundamental studies of plasmonic devices and coherent probing of sub-wavelength size (<λ/10) resonators [13-16]. This research feeds into engineering of novel THz optical components, such as negative refractive index materials, magnetic mirrors and filters [17-19].To date, different near-field probing schemes have been developed and implemented for imaging systems [13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], exploiting either scattering tip probes (known as apertureless probes) [23][24][25][26][27][28] for achieving nanometer-level resolution, or sub-wavelength size metallic aperture probes (a-SNOM) [14][15][16]22], electro-optic probes [18,20], and miniaturized photoconductive detectors [13,19]. The latter approaches are highly versatile and robust for large-scale (100 µm -3 mm scale) near-field subwavelength resolution THz microscopy and spectroscopy, and they have enabled investigations of macroscopic THz devices (including metamaterials [17][18][19], waveguides [29], and resonators [13-16]) and inspection of biological tissues [6].…”