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We demonstrate a novel approach to the problem of express diagnostics based on THz spectral features of the breast cancer and THz emission and detection provided by the topological edge channels of silicon nanosandwich-structures.
Transient-type stimulated emission in the terahertz frequency range has been achieved from silicon crystals doped by phosphorus and bismuth donors under optical excitation by a few picosecond-long pulses generated by the infrared free electron lasers, FELIX and CLIO. The lasing emission occurs due to a population inversion based mechanism for different interpulse intervals (40 ns, 20 ns, 16 ns, 1...
We designed and microfabricated a (2×2) silicon platelet horn antenna at 560 GHz, which is the highest frequency ever among silicon corrugated horn antennas. This was enabled by a silicon compression pin alignment technique of which inaccuracy is less than ± 2 μm in layer-to-layer. The simulation results show that the return loss and gain across the operation frequency of 490–600 GHz are approximately...
We demonstrate a novel approach to the problem of THz emission and detection by quantum Faraday effect that manifests itself in conductance of topological edge channels of silicon nanosandwich-structures.
We present a THz heterodyne detector based on a single layer graphene field effect transistor (GFET) integrated with a bowtie antenna at 400 GHz. The heterodyne detection is achieved by coupling RF and LO signals quasi-optically to the same GFET. The down converted IF signal is extracted via a coplanar stripline connected to the GFET source and drain terminals. The measured IF bandwidth is 5 GHz.
We present two terahertz detectors composed of microbolometer sensors (vanadium oxide and silicon pn diode) and metamaterial absorbers monolithically integrated into a complementary metal oxide semiconductor (CMOS) process. The metamaterial absorbers were created using the metal-dielectric-metal layers of a commercial CMOS technology resulting in low-cost terahertz detectors. The scalability of this...
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...
We applied terahertz (THz) time-domain spectroscopy (THz-TDS) to reveal the mechanism of the relativistic Doppler reflection of THz light from a photo-induced plasma front in a silicon wafer. The frequency up-shift caused by the Doppler reflection was identified by measurement of the reflected THz waveforms and compared to the calculated results obtained using the one-dimensional finite-difference...
We report the results of investigations of thin films of the composite based on the semiconducting polymer polyfluorene and graphene oxide particles with different content of the graphene oxide by terahertz time-domain spectroscopy.
Germanium-on-silicon waveguides are designed, fabricated and characterized with a novel near-field infrared spectroscopy technique that allows on-chip investigation of the in-coupling efficiency. On-chip propagation along bends and straight sections up to 0.8 mm is demonstrated around λ = 6 μm.
The sensitivity of state-of-the-art superconducting far-infrared detectors is such that astronomical observations at these wavelengths are limited by photon noise from the astronomical source unless a method of restricting the spectral bandpass is employed. One such method is to use a high resolution Fabry-Pérot interferometer (FPI) in conjunction with a lower resolution, post dispersing system, such...
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...
The operating frequency of InP high electron mobility transistor (HEMT) based amplifiers has moved well in the submillimeter-wave frequencies over the last couple of years. Working amplifiers with substantial gain in waveguide packages has been reported beyond 700 GHz. When cooled cryogenically, they have shown significant improvement in their noise temperature. This has opened up the real possibility...
We present an experimental investigation of the nonlinear response of acceptor impurities in semiconductors to coherent excitation with intense THz fields. In Zn-doped GaAs, we observed a well-defined saturation of the transition from the impurity ground state to the excited states and valence band. In B-doped Si, however, there is a clear indication of field-induced distortion of the impurity energy...
Semiconductors and metals respond to strong electric fields in a highly nonlinear fashion. Using single-cycle THz field transients it is possible to investigate this response in regimes not accessible by transport-based measurements. Extremely high fields can be applied without material damage, intrinsic, undoped materials can be studied, and field-induced electron emission into free space can be...
This paper describes general considerations for the design of highly efficient and distributed room-temperature Terahertz detectors and transmitters in (Bi)CMOS technologies. It discusses the design of industrial-grade scalable terahertz imaging systems. This necessitates a deep understanding of the process technologies front-end and the back-end, as well employing innovative architectures of terahertz...
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 design a T-shape structure reflecting mirror covered a gold thin film on the high-resistivity silicon substrate (ρ=1000 Ω·Cm) for the detector array. The electric field distribution of the T-shape structure is simulated by using finite difference time domain (FDTD) solutions in the frequency range from 300 GHz to 400 GHz. The electric field can be gathered in the central area of the silicon substrate...
We report on the first experimental observation of the intrinsic terahertz photoluminescence of semiconductors caused by optical transitions in free excitons. The experiments were carried out at helium temperatures on Si crystals.
We used a 4-N, N-dimethylamino-4'-N'-methyl-stilbazolium tosylate (DAST) crystal coupled with a Si prism to detect THz pulsed radiation in heterodyne electro-optic sampling scheme. The detection efficiency is higher than that for a DAST crystal without a prism, as well as for a LiNbO3 crystal with a Si prism.
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