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Passive imaging cameras at sub-millimeter wavelengths are currently entering a new era with the development of large format arrays of direct detectors. Several of these arrays are being developed with bare absorbing meshes without any antenna coupling (lens or horn) structures. This paper uses a spectral electromagnetic model to analyze the performance of absorber based focal plane arrays in comparison...
Active Terahertz-wave imaging systems play a significant role in security and surveillance applications. This paper describes a 0.14THz near-field imaging system, which consists of a signal generator and acquisition unit, a transceiver front end, a digital signal process unit and a motor control unit. Base on the two-dimensional synthetic aperture technique and the image reconstruction algorithm,...
We demonstrate a novel architecture for a THz near-field probe, which enables coherent imaging with subwavelength spatial resolution using THz quantum cascade lasers. An InAs nanowire acting as a THz detector based on the field effect transistor concept is integrated inside a subwavelength input aperture of the near-field probe to detect intensity of the THz field and its phase. To determine the phase...
We propose and demonstrate a novel near-field probe, resonant at terahertz (THz) frequencies. A conical metal tip, with length 50–1000 μm is fabricated directly to the surface of a semiconductor surface, acting as a radially-polarized THz source. High field confinement is seen at the apex of the probe. The scattering efficiency is frequency dependent, and is likely related to the dipolar resonance...
Sparse multistatic array designs that are based on the effective aperture concept enable real-time and cost-effective 3D CW terahertz imaging solutions. However, reduced system costs or challenging imaging scenarios eventually require a violation of the Nyquist sampling criterion, which leads to the appearance of grating lobes in the terahertz image. We propose a method to suppress grating lobes by...
Terahertz (THz) plasmonic structures of subwavelenght rectangular apertures in a periodic square lattice were developed on aluminum surface. By varying the incident angle, the reflectance spectra of the plasmonic samples were measured with far-infrared Fourier transform spectrometer in the frequency range of 1–15 THz. The change in the design of subwavelenght apertures revealed the resonant features...
We describe an approach to terahertz near field microscopy based on integrating custom-designed photoelectric radiation sources with near field probes on a single chip. Here we present results from new planar and conical probe designs.
Metasurfaces based on sub-wavelength patterning have major potential for arbitrary control of the wavefront of light by achieving local control of the phase, amplitude and polarization and allowing greater functionality and more compact devices. The resulting “flat” optical components hold promise to replace refractive and diffractive optics in a large number of applications ranging from camera modules...
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