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A differential transmission line sensor at 100 GHz is designed and analyzed. Artificial transmission lines are used in a coplanar waveguide configuration. Its high sensitivity to dielectric changes in thin layers enables detection of DNA hybridization or antibody-antigene binding processes for biomedical applications. It is simple, cheap and easy to combine with semiconductor mm-Wave sources and detectors.
A VOx microbolometer detector coupled with thin-film spiral antenna was fabricated by metal-organic decomposition. Temperature coefficient of resistance of the microbolometer was 4.7 %/K at 300 K and the responsivity was 120 V/W for 94 GHz electromagnetic wave radiation at a bias current of 0.5 mA.
We report the measured performance characteristics of a broadband (0.2 – 10 THz) bolometer instrument based on thin film superconducting technology. The technology is designed for operation both in liquid helium cryostats but also in an electrical cooling platform. We report a number of significant advantages that accrue to superconducting technology compared to semiconductor devices. Single pixel...
We have demonstrated THz wave detection using an ultra-compact THz probe. Our THz probe is based on an electro-optic-sampling method, which has been developed as an electric field prober in the microwave frequency range. The THz probe is a fiber-based system operating at the 1.5 µm-band. The dimensions of the EO probe unit were 10mmφ × 60mm-long. By using the EO probe, a 2 THz-wide THz wave was successfully...
We report a gate-voltage-controlled terahertz (THz) detector based on a two-dimensional electron gas (2DEG) field-effect transistor. The electron density of the 2DEG can be varied with the gate voltage. In this way, we controlled the amplitude of the THz detected signal by the gate voltage, indicating the role of the external switch for the THz detection.
We have demonstrated terahertz (THz) passive imaging of a cold object using a 4 K-cryocooled THz photoconductive detector with BLIP at around 1.5–2.5 THz. In our imaging system, we achieved a resolution of 240 µm, a background limited NEP of 7.7×10−15W/√Hz and a NETD of 11 mK. We have measured temperature dependence of THz intesity emitted from a sample with the emissivity of 0.99. The result shows...
Photoconductive switches have been extensively studied in time domain spectroscopy (TDS) as THz sources/ detectors. The commonly used devices consist of metal-semiconductor-metal (MSM) structure where Gallium Arsenide (GaAs) is the active layer. In this work, an approach consisting of using semiconducting single-walled carbon nanotubes (s-SWCNTs) instead is proposed. The pristine results showing the...
A theoretical study on the THz absorption efficiency and responsivity of Kinetic Inductance Detectors (KIDs), done by calculating the change on the variation of the microwave resonators frequency due to the kinetic inductance, is presented. Two radiation coupling mechanisms are compared: an antenna-coupled KID and a direct-absorption KID.
PTB, the metrology institute of Germany, operates the worldwide first and still unique THz detector calibration facility traceable to International System of Units. A research and development project in cooperation with a manufacturer of pyroelectric detectors is dedicated to develop suitable THz detectors.
Double-grating-gate field-effect transistors have a great potential as terahertz detectors. The double grating gate serves not only for carrier density tuning but also as an efficient THz radiation coupler. Low and high magnetic field detection results are used to determine the electron mobility and electron concentration, respectively, in the different parts of the channel.
Results on identification of liquids by a Josephson detector with a dielectric waveguide coupling are presented. Broadband and frequency-selective modes of the Josephson detector were used to extend a spectral bandwidth from 1 GHz to 500 GHz. A characterization of a liquid identifier was demonstrated for alcohols, acetone and water.
In this paper, a Lüneburg lens is characterized with millimeter waves. This gradient index lens is used in both transmission and reflection configurations.
Achieving absolute power measurement is not so easy in the THz range. In this paper, we describe a simple method to perform power measurement no more expressed in a.u. but in Watt. For a 3.8 THz single-plasmon Quantum Cascade Laser, 28.8 mW peak power was measured with 12:1% relative uncertainty. The operating method described is not really a metrologic one but one that can be easily performed in...
Several options for THz emitters and detectors operated at pump wavelengths around 1560 nm were investigated. Results from photoconductive antennas on In0.53Ga0.47As-based epilayers as well as DAST crystals are presented. Furthermore, the use of standard LTG GaAs antennas without frequency doubling is explored.
We report on Terahertz wireless communications and fast imaging experiments at 300 GHz, using nanometer-sized transistors as detectors. The physical mechanism of the detection is related to the overdamped plasma waves in the transistor channel.
MKIDs are cryogenic (<1K) detectors suitable for a broad range of wavelengths and combine a high sensitivity with an intrinsic high-multiplexing capability. We plan to use the knowledge acquired in the development of MKIDs to develop a passive stand-off terahertz imager for specialized security and biomedical applications. The imager will comprise of several subcomponents, such as the focal-plane...
Test chips with Si MOSFETs integrating bow tie antennas are investigated to check the polarization and frequency dependence of THz sensitivity. The azimuthal angle corresponding to the maximum sensitivity changes with the pixel position on the chip. This means that the surrounding pixels affect the bow tie radiation pattern and possibly contribute to the antenna coupling. The frequency dependence...
We have applied an ultrafast superconducting YBa2Cu3O7-δ (YBCO) detector to study the time jitter of the propagating electron bunches in a synchrotron. The jitter was determined from the coherent terahertz (THz) synchrotron radiation (CSR).
A multichannel lock-in was developed for the use in a multichannel Terahertz time-domain measurement (TDS) setup. The number of channels can be scaled from 1 channel up to 128 channels regarding the application.
A novel passive THz imaging system of single channel and optical-mechanical scanning is described. It employs a Cassegrain antenna of 390mm in diameter, and achieves the two-dimensional scanning imaging via the cooperation of a line scanning mirror, driven by a crank-rocker mechanism in a high speed, and the motion of the frame scanning mirror. Thus, the system has many advantages such as low cost,...
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