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- 摘要
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- 实验方案
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Carrier Dynamics in SnS<inf>2</inf> Single Crystals and Vertical Nanostructures: Role of Edges
摘要： SnS2 is a member of the van der Waals 2D layered materials family. Its moderate bandgap, environmental stability and high carrier mobility makes it attractive for solar energy conversion application. We explore how nanostructuring SnS2 in the form of vertically-aligned nanoflakes to increase the surface area impacts the lifetime and microscopic conductivity of photoinjected carriers compared to the bulk SnS2. Increased surface area and the presence of edges is beneficial to the efficiency of SnS2 photoanode performance but it comes at a cost of increased carrier trapping at surface and edge states.
关键词： THz spectroscopy,van der Waals materials,SnS2,carrier dynamics,nanostructuring
更新于2025-09-11 14:15:04
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Compact silicon-micromachined wideband 220-330 GHz turnstile orthomode transducer
摘要： This paper reports on a turnstile-junction orthomode transducer (OMT) implemented by silicon micromachining in the 220 – 330 GHz band. Turnstile OMTs are very wideband and allow for co-planar ports, but require accurate and complex geometries which makes their fabrication challenging at higher frequencies. The compact 10 x10 x0.9 mm3 OMT-chip presented in this paper is the first micromachined full-band OMT in any frequency range, and only the second turnstile OMT implemented above 110 GHz. The measured insertion loss (0.3 dB average, 0.6 dB worst-case) and the cross-polarization (60 dB average, 30 dB worst-case) over the whole waveguide band represent the best performance of any wideband OMT, regardless of design or fabrication technology, in the 220 – 330 GHz band. The return loss with 22 dB average (16 dB worst-case) is comparable or better than previous work. The paper discusses design considerations and compromises of this complex 9 layer silicon micromachined device, including the influence of sidewall slopes, underetching, and post-bonding misalignment between the chips. It is shown that for a device which is very sensitive to geometrical variations, such as a turnstile OMT, it is necessary to anticipate and compensate for any fabrication imperfections in the design to achieve high RF performance.
关键词： terahertz,mmW,DRIE,orthomode transducer,turnstile,silicon micromachining,THz,millimeter wave,MEMS,OMT
更新于2025-09-11 14:15:04
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Broadening the IF band of a THz hot electron bolometer mixer by using a magnetic thin film
摘要： To expand the intermediate frequency (IF) band and improve the sensitivity of a hot electron bolometer mixer (HEBM), we proposed and examined a new HEBM structure using a magnetic thin film. We found that it was possible to suppress the superconductivity of the 5-nm thick niobium nitride (NbN) thin film by the addition of a 1.8-nm thick nickel (Ni) thin film. It was also confirmed that the superconductivity disappeared in the Au (70 nm)/Ni (1.8 nm)/NbN (5 nm) tri-layer for forming the electrodes of the HEBM. By using the magnetic thin film for the electrodes, we suggested that the superconductivity of the HEBM strip would be affected and that hot spots would form near the electrodes. This approach is effective for shortening the hot electron drift length and will lead to the expansion of the IF bandwidth. We think that the new structure lowers the required local oscillator (LO) power and improves the HEBM sensitivity by suppressing the proximity effect under the electrode. The IF bandwidth of the fabricated Ni-HEBMs was evaluated at 1.9 THz. We confirmed that the IF bandwidth expands, and the evaluated bandwidths were in the range of 5.1–5.7 GHz at 4 K. Ni-HEBMs with 0.1 μm strip length were also fabricated and evaluated. The IF bandwidth was about 6.9 GHz at 4 K.
关键词： hot electron bolometer mixer,THz,magnetic thin film,superconductivity,intermediate frequency band
更新于2025-09-11 14:15:04
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The New Concept of Nano-Device Spectroscopy Based on Rabi–Bloch Oscillations for THz-Frequency Range
摘要： We considered one-dimensional quantum chains of two-level Fermi particles coupled via the tunneling driven both by ac and dc ?elds in the regimes of strong and ultrastrong coupling. The frequency of ac ?eld is matched with the frequency of the quantum transition. Based on the fundamental principles of electrodynamics and quantum theory, we developed a general model of quantum dynamics for such interactions. We showed that the joint action of ac and dc ?elds leads to the strong mutual in?uence of Rabi- and Bloch oscillations, one to another. We focused on the regime of ultrastrong coupling, for which Bloch- and Rabi-frequencies are signi?cant values of the frequency of interband transition. The Hamiltonian was solved numerically, with account of anti-resonant terms. It manifests by the appearance of a great number of narrow high-amplitude resonant lines in the spectra of tunneling current and dipole moment. We proposed the new concept of terahertz (THz) spectroscopy, which is promising for different applications in future nanoelectronics and nano-photonics.
关键词： ultrastrong coupling,Bloch-oscillations,THz-spectroscopy,Rabi-oscillations
更新于2025-09-11 14:12:44
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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris, France (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Terahertz Metrology at PTB
摘要： Terahertz (THz) metrology is performed at the THz radiometry working group of PTB by offering a unique calibration service of the THz power responsivity of suitable detectors in the spectral range from 0.7 THz to 5 THz. A molecular gas laser enables a calibration uncertainty of < 2 % which was proven by a pilot comparison between the metrology institutes of China, USA and Germany. Usually, the THz power scale is disseminated by novel pyroelectric thin-film detectors. Moreover, these detectors can be applied as a reference material to check the precision of transmission and reflection measurements in the far-infrared to sub-millimeter range.
关键词： transmission and reflection measurements,Calibrated THz detector,THz reference material,THz power measurement
更新于2025-09-10 09:29:36
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An empirical formula for temperature adjustment of complex permittivity of human skin in the terahertz frequencies
摘要： The Terahertz (THz) frequency region of the electromagnetic spectrum is defined as radiation of 0.1–10.0 (cid:1) 1012 Hz. There is limited knowledge of the skin absorption properties of THz, and there are no data on long-term exposure. Given the expanding security and industrial applications of THz, there will be an increase in the incidental and purposeful exposure of humans to this frequency range. Most incident THz radiation is absorbed within the first 0.3 mm of soft tissue; thus, there is a need to develop a reliable way of modeling the effect of this radiation on human skin. This paper analyzes the data available on the dielectric properties of skin in the THz range, with reference to differences at room and body temperature. The intent is to develop a technique for standardization of measurements obtained at diverse temperatures, allowing for a better comparison of different datasets. The adjustment is standardized to real (e0) and imaginary (e00) parts of complex permittivity (e(cid:3)) as described by Kaye and Laby [1995] and Lajevardipour et al. [2016].
关键词： terahertz,temperature,THz,skin,water content
更新于2025-09-10 09:29:36
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Developments of Equipment for sub- THz Collective Thomson Scattering in LHD
摘要： Equipment for collective Thomson scattering diagnostics in the Large Helical Device has been developed. The probe beam source is a 303 GHz Gyrotron. It operates in a pulse mode. No parasitic mode is excited during the whole pulse width including the turn-on and turn-off phases. Single mode oscillation at several frequencies has been confirmed. For power transmission, a 3.5 inch corrugated waveguide line installed for electron heating with lower frequency gyrotrons will be used. The test with the 303 GHz gyrotron has shown a sufficiently low transmission loss.
关键词： Gyrotron,collective Thomson scattering,corrugated waveguide,sub-THz,Large Helical Device
更新于2025-09-10 09:29:36
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Ultrafast Control of Even-Order Harmonic Generation from Solids by an Intense Terahertz Field
摘要： Nonperturbative even-order harmonics, physically forbidden in centrosymmetric crystals, are observed from both insulator (diamond) and semiconductor (silicon) samples driven by IR pulses, when in addition an intense THz electric field is applied to the solid. The time-resolved study of the high-harmonic spectra with the temporal profile of the THz electric field suggests a transient THz-field-induced symmetry reduction. We also investigate the harmonics’ yields depending on the angles of the linear IR and THz polarizations with respect to the crystal axes. This work might pave the way for THz-based symmetry control in solids with important ramifications for petahertz electronics.
关键词： symmetry reduction,petahertz electronics,Nonperturbative even-order harmonics,THz electric field,centrosymmetric crystals
更新于2025-09-10 09:29:36
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Water-based Terahertz Metamaterial for Skin Cancer Detection Application
摘要： We present a highly sensitive detection of skin cancer using a novel water-based (THz) metamaterial (MM) used semiconductor film. We apply the application of terahertz pulsed imaging (TPI) in reflection geometry for the study of skin tissue and related cancers. As a refractive index (RI) sensing application of the proposed device, there will be shown with placing different sensing materials in the biosensor design, the effective RI will also change that in turn leads to measuring the sensitivity of the biosensor to detect the normal skin and Basal Cell Carcinoma (BCC). The RI FOM value of the proposed device is much higher than for the sensor using semiconductor film, to detect biomarkers in the literature. Significantly, the sensitivity increases by about 117 um/RIU and the RI FOM increases by more than 20.53. This results from a combination of size-related factors, leading to field enhancement accompanying strong field localization. We observed the resonance-frequency shift of the THz MM following the RI changing of the detected skin. The dip reflectance resonance has a blue-shift for normal skin. Finally, we suggest that this water-based MM can be used to control of the gene expression. The advantage of our design depends on two factors. Firstly, we used the MM structure, which has micro-scale, and the smaller the size of the structure, the more sensitive to the changes in the RI. Secondly, we used water in our structure, which is very well-suited to the human body and are highly bio-absorbable and inexpensive which is abundantly found in nature.
关键词： bio-absorbable metamaterials,Skin Cancer detection,THz Metamaterials,Semiconductor Biosensor,Refractive Index Sensor,control of the gene expression
更新于2025-09-10 09:29:36
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Super-radiative self-compression of photo-injector electron bunches and the use of this effect for realization of a THz source based on spontaneous coherent emission from a short dense electron bunch
摘要： Laser-driven photo-injectors allow formation of compact and accessible sources of dense electron bunches with a moderate energy of 3–6 MeV, picosecond pulse durations, and charges of up to 1 nC and even greater. These bunches can be used for realization of comparatively simple and compact terahertz sources operating in the regime of spontaneous coherent undulator radiation. This type of radiation is realized, when the effective axial length of bunches is shorter than the radiation wavelength, so that the wave packets emitted by each of the electrons add up basically in phase. The THz source based on the spontaneous emission has a number of advantages as compared to the more traditional free-electron laser (FEL) based on the undulator emission induced due to bunching of a long electron beam by the radiated wave. These are a relatively high efficiency of the emission from the “ready-for-radiation” bunch, a narrow frequency band of the radiated rf signal in a system without a feedback system and an input rf signal, and the phase of the radiated rf signal fixed by the electron bunch phase. These advantages make the THz source based on the spontaneous emission attractive for a number of important applications, including the use of synchronization of such an oscillator with the X-ray FEL in pump-probe experiments.
关键词： spontaneous coherent emission,photo-injector electron bunches,Super-radiative self-compression,THz source
更新于2025-09-10 09:29:36