Towards multipixel THz Schottky diode detector with a single RF output line

We propose the design of a dual-pixel array of Schottky diodes. Each diode is fixed between the bow-tie antenna arms on top of a SI-GaAs membrane acting as a waveguide backshort for efficient coupling of the antenna to the feedline of high-directivity horn. The detector utilizes a single RF output line: microwave reflectometer is used for the readout. The pixels are equipped with dual-mode resonator filters to eliminate the cross-talk. We evaluate the design proposed via numerical simulation and performance tests of the array subunits: NEP of 300 pW/Hz0.5 and dynamic range of 24 dB are demonstrated at 137.5 GHz.

Y-Shaped Demultiplexer Photonic Circuits Based on Detuned Stubs: Application to Radiofrequency Domain

We present a theoretical and experimental study of photonic demultiplexers based on detuned stubs. The demultiplexers consist of Y-shaped structures with one input line and two output lines. Two different types of structures are proposed to achieve a selective transfer of a single mode in one output line without disturbing the second one. (i) In the first platform each output contains two different stubs attached at two different sites (U-shaped resonators). We derive in closed form the geometrical parameters of the stubs to achieve a selected frequency in each line while keeping the other line unaffected. The frequency selection can be made on the basis of two different mechanisms, namely a Fano or an electromagnetic induced transparency (EIT) resonance. Consequently, different demultiplexing schemes can be designed by a combination of the two mechanisms, such as Fano-Fano, Fano-EIT or EIT-EIT. In particular, the width of the Fano or EIT resonances can become zero for an appropriate choice of the stubs’ lengths, giving rise to trapped modes also called bound in continuum states (BICs) with infinite quality factors. We also show that the crosstalk between the two outputs can reach minimum values around −45 dB. (ii) In the second platform, each output line contains a photonic comb with a defect stub. The latter is appropriately designed to filter one or a few frequencies in the bandgap of the photonic comb. The analytical calculations are performed with the help of the Green’s function method which enables us to derive the transmission and reflection coefficients as well as the density of states (DOS). These results are confirmed by experimental measurements using coaxial cables in the radio frequency domain.

Enhancing the Triboelectric Nanogenerator Output by Micro Plasma Generation in a Micro-Cracked Surface Structure

Energy harvesting, especially for powering low-power internet-of-things (IoT) devices, is gaining attention in recent years. Triboelectric nanogenerators have been studied to improve the output by applying a structure that can concentrate electrons on the surface of the generator materials. For enhancing the triboelectrification output, we herein focused on the power output line. A method for increasing the amount of electrons on the power lead by potential difference and their acceleration was studied. A rod was shaken by external vibrations; the accumulated charges were discharged in a manner similar to that of a lightning rod. Micro plasma was generated when the rod made contact with the mating micro-cracked surface innumerable times. The micro-cracked surface was fabricated with a diamond tip moving horizontally to the surface. As the resistance of the micro plasma was close to zero, the amount of electron movement was instantaneously accelerated. This type of triboelectric generator can be fabricated in the form of an electric box. By using this triboelectric power amplifier, voltage can be amplified 2 to 3 times, and the current can be amplified 10 to 15 times; thus, enhanced energy harvesting efficiency is attained.

Software driver for working with different types of SPI interfaces

Field-Programmable Gate Arrays (FPGAs) are configurable integrated circuits whose logic is defined through programming. The use of FPGAs makes it possible to obtain devices capable of changing the configuration, adapting to a specific task due to their flexibly changeable, programmable structure. When developing complex devices, ready-made IP-cores can be used as components for design. The use of software IP-cores allows them to be used most effectively in the final structure, to a significant extent to reduce design costs. A software driver has been developed for working with different types of SPI interfaces (Serial Peripheral Interface), which implements switching the input-output line when transmitting data through a FPGA.

Design of multiplexing circuit using electro-optic effect based optical waveguides

The multiplexer is a combinational circuit that transfers multiple data inputs over a single output line. The input data are selected and transferred to the output line based on the selection line. In this work, 2 × 1 and 4 × 1 multiplexer is proposed. The proposed multiplexer has been worked out using the electro-optic principle. It is implemented using lithium niobate-based Mach–Zehnder interferometer (LN-MZI). LN-MZI is used as an optical switching device. The performance parameters extinction ratio, contrast ratio and insertion loss have been computed and found 31.31, 28.02 and 0.043 dB respectively.

Acoustic demultiplexer based on Fano and induced transparency resonances in slender tubes

We give an analytical demonstration of the possibility to realize a simple phononic demultiplexer based on Fano and acoustic induced transparency resonances. The demultiplexer consists of a Y-shaped waveguide with an input line and two output lines. Each output line contains two stubs grafted either at a given position or at two positions far from the input line. We derive in closed form the expressions for a selective transfer of a single propagating mode through one line keeping the other line unaffected.

Research on Modified Hybrid Frequency Modulation Technology of Type-III Asymmetric CHB Multilevel Inverters

Asymmetric Cascaded H-bridge (ACHB) level inverters can output more voltage waveforms with fewer cascaded units while ensuring the quality of output voltage waveforms, so they have attracted more and more attention. Taking the topology of Type-III asymmetric CHB multilevel inverters as the research object, a Modified Hybrid Frequency Pulse Width Modulation (MHF-PWM) strategy is proposed in this paper. This modulation strategy overcomes the local overshoot of low-voltage unit in the presence of traditional Hybrid Frequency Pulse Width Modulation (HF-PWM), thus completely eliminating the low frequency harmonics in the output voltage waveform of Type-III ACHB nine-level inverters, and the Total Harmonic Distortion (THD) of output line voltage of the modulation strategy is lower than that of PS-PWM strategy in the whole modulation degree, which effectively improves the quality waveform of the output line voltage. At the same time, the strategy can also improve the problems of current backflow and energy feedback caused by the high-voltage unit pouring current to the low-voltage unit, thereby reducing the imbalance of the output power of the high-voltage and low-voltage units. Finally, the Matlab/Simulink simulation model and experimental platform are established to verify the validity and practicality of the modulation strategy.