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POWER CHARACTERISTICS OF A T-JUNCTION OF RECTANGULAR WAVEGUIDES WITH A MULTI-ELEMENT MONOPOLE-SLOTTED COUPLING STRUCTURE
摘要： Rectangular waveguide junctions are widely used antenna-waveguide devices. For this reason analysis of the impact of impedance insertions on the electrodynamic characteristics of the junctions is of great importance for practical applications. The paper suggests a mathematical model of an E-plane T-junction of rectangular waveguides with a three-element monopole-slot structure of the coupling. The model has been developed on the basis of an approximate analytical solution of the equation set for the currents obtained by the method of induced electro- and magnetomotive forces. A peculiarity of the model is simultaneous consideration of two impedances. These are a variable along the monopole axes surface impedance and a constant impedance distributed across the end face of the lateral semi-infinite waveguide. Multiparametric investigations have been performed of the power characteristics of the junction for the single-mode operation regime of the waveguides, including the case of covering the end face of the lateral waveguide by a metamaterial layer. The possibility is investigated of the efficient use of impedance coats in the capacity of control elements of sharing the power between the output arms of the waveguide junction.
关键词： impedance coating,metamaterial,waveguide junction,resonant slot,impedance monopole
更新于2025-09-11 14:15:04
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Miniaturized Optoelectronic SPR Sensor Based on Integrated Planar Waveguide and MIM Hot-Electron Photodetector
摘要： There is an increasing interest in miniaturized surface plasmon resonance (SPR) sensors for portable biosensing. Toward this goal, removing the use of an external spectrometer is a fundamental step to miniaturize the Kretschmann SPR sensors. In this article, we have proposed a new architecture of the SPR sensor with an electrical response in which the integrated hot-electron photodetector replaces the traditional spectrometer. In this device, the metal–insulator–metal (MIM) junction and planar waveguide (PWG) are integrated together as a multilayer. The structure is excited by a broad-spectrum light-emitting diode (LED) in the near-IR region. The coupling between the surface plasmon polariton (SPP) mode of the MIM junction and the PWG mode leads to predominated photoabsorption in the top layer of the MIM junction within a selective narrowband of excitation bandwidth. The center wavelength of the absorption band is determined by the refractive index of the analyte. We demonstrate that based on the hot-electron injection in the MIM junction, the open-circuit voltage of the MIM junction in the proposed architecture is proportional to the refractive index of the analyte and this feature can replace the wavelength interrogation of the SPR sensors. We show that electrical sensitivity can be improved by introducing an indium tin oxide (ITO) layer as a hot-electron blocker above the bottom electrode of the MIM junction. The response of the proposed sensor is calculated in detail, and its optical sensitivity is estimated to be ～8000 nm/refractive index unit (RIU), which turns to an electrical sensitivity of 12.5 V/RIU in our device.
关键词： refractive index sensor,metal–insulator–metal (MIM) junction,surface plasmon resonance (SPR),Hot-electron
更新于2025-09-11 14:15:04
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Schottky junction-based thermophotovoltaic-thermionic devices
摘要： The conceptual model of a Schottky junction-based thermophotovoltaic-thermionic device (SJTTD) that can simultaneously convert thermally emitted electrons and photons into electricity is proposed, where the cathode of the TIC and the anode/p-type silicon interface forms the SJ. The impacts of space charge effect (SCE) on the TIC and radiative recombination on the TPVC are taken into account. According to the theory of statistical physics, analytical expressions for the total power output density and energy conversion efficiency of the SJTTD are derived. The maximum power output density and efficiency are calculated numerically by optimizing the key parameters of the two subsystems. Further, the parametric optimum criteria are provided. The optimally operating states of the ideal and non-ideal SJTTDs are compared. The results show that selecting the cathode materials with high emissivity can significantly enhance the performance. The proposed model can be helpful for developing high-efficient hybrid electron devices.
关键词： Schottky junction,Optimum criterion,thermophotovoltaic,thermionic emission
更新于2025-09-11 14:15:04
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Tiny nano-scale junction built on B/N doped single carbon nanotube
摘要： The characteristic sizes of carbon nanotube (CNT) based devices are constantly reduced. However, the continuous miniaturization is still facing many problems and requires innovative ideas and structures. By regular doping Boron and Nitrogen atoms in a semiconducting single-wall carbon nanotube (SWCNT), we have constructed an nano-scale junction with rectifying characteristics. The I-V curve of our junction resembles the I-V curve of an ideal diode with a p-n junction. This junction channel is about 0.6nm wide and 3.4nm long, and the footprint is 5.1nm long. Under 0.5V bias, the junction has a leakage current of -8.81×10-3 μA, a rectifying ratio Ion/Ioff of 0.716×103, and a current density of 10.52 mA/μm. Also, our study shows that how different dopant distribution influence I-V curve. Such a nano-scale regular doping method is effective and important, compared with the traditional random doping method.
关键词： B/N doped junction,I-V curve,density functional theory,non-equilibrium Green’s function,carbon nanotube,regular doping,electronic transport
更新于2025-09-11 14:15:04
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Optimizing the Nonlinearity and Dissipation of a SNAIL Parametric Amplifier for Dynamic Range
摘要： We present a quantum-limited Josephson-junction-based three-wave-mixing parametric amplifier, the superconducting nonlinear asymmetric inductive element (SNAIL) parametric amplifier (SPA), which uses an array of SNAILs as the source of tunable nonlinearity. We show how to engineer the nonlinearity over multiple orders of magnitude by varying the physical design of the device. As a function of design parameters, we systematically explore two important amplifier nonidealities that limit dynamic range: the phenomena of gain compression and intermodulation distortion, whose minimization are crucial for high-fidelity multiqubit readout. Through a comparison with first-principles theory across multiple devices, we demonstrate how to optimize both the nonlinearity and the input-output port coupling of these SNAIL-based parametric amplifiers to achieve higher saturation power, without sacrificing any other desirable characteristics. The method elaborated in our work can be extended to improve all forms of parametrically induced mixing that can be employed for quantum-information applications.
关键词： gain compression,Josephson-junction,three-wave-mixing,parametric amplifier,SNAIL,dynamic range,quantum-limited,intermodulation distortion
更新于2025-09-11 14:15:04
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Thermal Characterization of Quasi-Vertical GaAs Schottky Diodes Integrated on Silicon
摘要： This paper presents the ?rst thermal characterization of terahertz quasi-vertical GaAs Schottky diodes integrated on silicon. The devices are characterized using a thermore?ectance measurement technique. Heating and cooling temperature pro?les and 2-D temperature maps are obtained for 5.5-μm diameter diodes. From the measurements, we extracted the device thermal resistances, anode temperatures, and thermal time constants. Equivalent circuit and ?nite-element models are developed to study the device geometry, and extract unknown material thermal parameters. The devices are also characterized using an electrical transient method, and the temperature and cooling transients found from both techniques are compared. The quasi-vertical diodes show comparable thermal resistance and a faster transient response compared to other terahertz Schottky diodes reported in the literature.
关键词： Schottky diode,thermal characterization,imaging,thermore?ectance,thermal parameters,Heterogeneous integration,junction temperature
更新于2025-09-11 14:15:04
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[IEEE 2017 IEEE Workshop on Recent Advances in Photonics (WRAP) - Hyderabad (2017.12.18-2017.12.19)] 2017 IEEE Workshop on Recent Advances in Photonics (WRAP) - Effect of Junction Profile on the Phase and Loss Characteristics of a Silicon Optical Modulator
摘要： In this paper, numerical analysis has been done to calculate the modal, phase and loss characteristics of a silicon rib PN phase shifter for three samples with different junction pro?les. Each sample has been compared based on performance characteristics to show that a graded junction gives better performance compared to an abrupt junction phase shifter.
关键词： phase shifter,rib waveguide,silicon modulator,insertion loss,PN junction,Graded junction
更新于2025-09-10 09:29:36
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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) - Improvement of an Automated AC/DC Voltage Transfer Calibration System at the Standards and Calibration Laboratory
摘要： This paper describes the recent improvement of the AC/DC voltage transfer calibration system at the Standards and Calibration Laboratory (SCL) of Hong Kong. The measurement system has been recently modified with an enclosure, a switching relay and an automated control program. With these new implementations, the switching time and the switching pattern were studied and compared with the original design.
关键词： automation,AC/DC voltage transfer,single junction thermal element,multi junction thermal element
更新于2025-09-10 09:29:36
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Slot Lens Antenna Based on Thin Nb Films for the Wideband Josephson Terahertz Oscillator
摘要： An oscillator based on the distributed tunnel superconductor-insulator-superconductor junction with an ultrawide operating bandwidth of up to 100% of the central frequency seems to be a promising type of directional source of continuous electromagnetic radiation in the terahertz frequency range. In this paper, we propose a scheme of a terahertz oscillator integrated on a single microchip with a transmitting lens antenna with the slot structure in a 200-nm Nb film to radiate the signal into the open space. We also proposed and numerically simulated several designs of a planar slot antenna matched (in the input) with a Josephson oscillator and (in the output) with a silicon elliptical lens. The obtained results of the matching of the oscillator output power with the antenna of various designs operating in four frequency ranges: 250–410, 330–570, 380–520, and 420–700 GHz are presented. The antenna beam patterns and impedances are calculated as well.
关键词： terahertz,superconductor,slot antenna,oscillator,Josephson junction
更新于2025-09-10 09:29:36
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Elasto-electric coupling for direct electric field distribution measurement in semiconductor structures
摘要： Semiconductor materials are widely used in electronic industry, but their electrical characterization remains complex to estimate without a good model. It has already been shown that an elasto-electric coupling can be used to directly and non-destructively probe the electrical properties at the external interfaces of semi-conductor structures. In this paper, it is shown that such a coupling can also be used to probe the inner interfaces of semi-conductor structures. This capability is demonstrated by using a specific semi-conductor structure including a buried silicon p-n junction 720 lm away from the external electrodes. The signal generated by the elasto-electric coupling clearly shows separately the electric field at the electrodes and at the buried junction. The contact potential at the buried junction estimated from the measurements is in accordance with the semiconductor doping. This makes it possible to use an elasto-electric coupling for the complete characterization of semiconductor structures.
关键词： Pressure-Wave-Propagation method,elasto-electric coupling,semiconductor structures,p-n junction,electric field distribution
更新于2025-09-10 09:29:36