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This paper presents a low-cost silicon-based terahertz computed tomography system for industrial volumetric imaging. The THz-CT scanner comprises a single radiator and detector at 490 GHz and a PTFE-lens based optical train that is fixed inside a portable cage system. It features a 2.5 mm resolution limited by the effective lens aperture and offers up to 62 dB SNR in chopped and 38 dB in a continuous-wave...
The design and performance analysis are presented for a passive uncooled radiometer pixel suitable for integration in 28nm CMOS technology. In the configuration a single wideband antenna, operating from 200 GHz to 600 GHz, is connected to a pn-junction diode. Including the antenna-detector impedance mismatch, the detector shows an average NEP of 2.71 pW/√Hz such that, together with the antenna, the...
THz radiation can couple in various undesired ways to THz detectors, e.g. through wires or contact pads, aggravating calculation of sensible values for the device responsivity. We therefore investigate coupling of THz radiation to antenna-less large area field-effect transistors with dimensions in the range of the THz spot size proving that only a very small fraction of power is coupled through the...
We examine array configuration and silicon-lens integration of asymmetric-dual-grating-gate high-electron-mobility transistors (A-DGG HEMTs) as plasmonic terahertz detectors in order to enhance their external coupling efficiencies. We demonstrate 4-fold enhancement of the efficiency by an array of four series-connected detectors and 6-fold enhancement by the hyper-hemispherical silicon-lens integration...
This paper presents a high responsivity THz detector formed of two depletion mode pseudomorphic high electron mobility transistors (D-pHEMT) coupled to an on-chip bowtie antenna in GaAs 130 nm technology. The measured absolute responsivity of the integrated detector is 10 V/W at 250 GHz at a gate bias voltage of −0.3 V. A silicon lens attached to the GaAs substrate improves the responsivity of the...
We experimentally verify that the low external responsivity of nanostructured asymmetric-dual-grating-gate high-electron-mobility transistors (A-DGG HEMTs) as plasmonic terahertz detectors developed so far is attributed to their low external coupling efficiency. We separately demonstrate (1) 4-fold enhancement of the efficiency by an array of series-connected 4×1 detectors due to the increase in the...
This paper presents a quasi-spiral THz antenna which acts as an Infrared (IR) Fresnel zone plate lens. This antenna can be the base for compact THz — IR integrated dual band sensors. The proposed configuration consists of a submillimeter wave antenna (working at around 400 GHz) which acts as a modified Fresnel Zone Plate lens for the in the IR range (around 28 THz).
Dual band THz-IR receivers can be used in application within different fields. For instance, in radio-astronomy, dust emission in the infrared (IR) and submillimeter wave or THz ranges is used for star-formation characterization. This information is normally acquired by different detectors which operate at each of these frequencies; i.e. Terahertz and Infrared. The development of an integrated dual...
We demonstrate an integrated four quadrant detector in silicon for infrared light, based on integration of plasmonic splitting, focusing and plasmonic enhanced internal photoemission detection on a single silicon plasmonic chip.
We present a new flexible technology to generate broadband antireflection structures for the THz frequency range on planar and curved surfaces of silicon optics. Ultrashort laser pulses are used to ablate the surface in order to form subwavelength structures. Such structures effectively provide a gradual transition of the refractive index from air to silicon. We demonstrate antireflection structures...
Dust emission is used in space applications for star-formation characterization normally acquired by different detectors operating at Infrared (IR) and sub-millimeter wave (sub-mm wave) frequencies. An integrated dual band detector working at both frequency ranges will be described in this paper. The proposed configuration implements a spiral antenna working at sub-millimeter wave frequencies whose...
We have fabricated AlGaAs/InGaAs/AlGaAs heterostructure field effect transistors (HFET) with integrated on-chip antennas and we have measured their optical responsivity when mounted in a in-house developed quasi-optical package with a silicon substrate lens
This contribution presents the first demonstration of the applicability of the leaky lens antenna concept at THz frequencies. The antenna is integrated with a Kinetic Inductance Detector, so that the two of them function as an ultra sensitive detector over a bandwidth ranging from 0.15 THz to 1.5 THz. The system has been manufactured and characterized in terms radiation pattern properties and frequency...
This paper reports on the design of broadband lens-integrated differentially driven wire ring on-chip antennas for THz direct detectors in a state-of-the-art SiGe HBT technology. The antenna provides wideband detector operation on a high-permittivity substrate at least within the measured 650–1028 GHz, high radiation efficiency at THz frequencies on a bulk silicon substrate, layout fully compatible...
Future imaging applications in the submillimeter-Wave range (300GHz to 3THz) require RF systems that can achieve high sensitivity and portability at low power consumption levels. In particular, CMOS process technologies are attractive due to their low price tag for industrial, surveillance, scientific, and medical applications. Recently, CMOS-based detectors have shown good sensitivity up to 1THz...
A low noise, high quantum efficiency (QE) Ge photo diode was integrated in a standard 0.18 μm CMOS foundry process, enabling night imaging under moonless conditions in a high resolution CMOS image sensor (10 μm pitch, VGA). The Ge diode dark current measured at wafer probe (-45°C) in the imager chip is 25 fA per pixel and the pixel QE at λ=1.3 μm is 44% and 32% for best die at half and full VGA resolution...
To improve the image resolution of thermal imagers, which image objects by uncooled Focal Plane Arrays (FPAs) made up of two-dimension Infra-red (IR) detector arrays, detector size is decreased, and this results in the reduction of detector IR absorber area . However, reduction of IR absorber area may affect IR detector's sensitivity accordingly. In order to reduce the detector size without reducing...
In this paper, the optical design of astronomical detector array with SIS for 600-700 GHz is proposed. A unit has 127 pixel, and SIS junctions are coupled to double slot antennas and extended hemisphere lens made from Silicon or Alumina ceramics. A lens with multi-pixel system is compared to 1 lens with 1 antenna system (fly-eye)from the view point of antenna spacing, aberration, and beam efficiency.
A dual slot antenna integrated with zero bias Sb-heterostructure diode for direct detection of THz radiation is presented. The compact layout and high responsivity of the detector makes it suitable to design 2D focal plane THz imaging arrays. Further, we proposed and demonstrated that number of detectors supported by a fixed size silicon lens can significantly be increased by proper antenna modifications...
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