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9. Implementation of MIMO-SAR Imaging Based on Jamming Signal.

Author

Liu, Gaogao, Wang, Youming, Yang, Wenbo, Bao, Yuqian, and Wu, Hui

Abstract

Special attention has been devoted to joint waveforms based on radar signals to mitigate the tension of spectrum resources and simultaneously play a multifunctional role. Aiming at the shortcomings of conventional detection and jamming dual-functional systems, where wide beams are difficult to detect with high accuracy, while narrow beams are difficult to cover a wide range of jamming, this letter designs a multiple-input multiple-output (MIMO)-synthetic aperture radar (SAR) system with jamming capabilities. The characteristic of this signal is to use MIMO system multiple antennas to transmit frequency diversity wideband code division jamming signals to effectively generate wideband suppression jamming for conventional radars, including frequency-agile radars. At the same time, the wide beam characteristics of MIMO antennas can ensure the physical range of jamming. In addition, for the imaging part, digital beamforming (DBF) technology can be used to form the beam in a specific direction at the receiving end, resulting in high resolution. Simulation experiments confirm the system’s ability to achieve high-resolution imaging of specific target areas while maintaining robust jamming capabilities. [ABSTRACT FROM AUTHOR]

Published
2023
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36. One-dimensional photonic crystal surface plasmon nanolaser for on-chip optical interconnects

Author

LiChao Liu, Baolu Guan, HeQun Ding, and Wu Hui

Subjects
Mode volume, Materials science, business.industry, Nanolaser, Surface plasmon, Laser, Waveguide (optics), law.invention, Modulation, law, Q factor, Optoelectronics, business, Photonic crystal
Abstract

Optical devices can beyond the diffraction limit through surface plasmon technology and realize on-chip optical interconnection. A qualified on-chip light source needs to meet the following requirements: smaller size, lower power consumption and higher output power. In our study, a nanolaser is designed based on surface plasmon, and a 1D photonic crystal structure is combined with the etching periodic and taper holes in the transverse waveguide. We simulated the Q factor, Purcell factor, mode volume, and waveguide coupling efficiency of resonantor, and analyzed the output characteristics and modulation response characteristics of the laser. Studies have shown that the combo surface plasmon 1D photonic crystal nanobeam cavity has excellent performance, the mode volume is only 0.15 (λ R /n)3, and the Q factor of 808, the Purcell factor of 106 and the waveguide coupling efficiency of 75% are achieved. The nanolaser we designed works at a wavelength of 1535nm, with a 3-dB bandwidth at a threshold pump rate of 134GHz, and produces an output power of more than 10μW at an injection current of 17μA, which meets the energy requirements of the nanometre chip light source. This ultra-small nanometre light source with low power consumption and high modulation rate provides a new solution for the next generation of on-chip optical interconnection.

Published
2021

41. Research on TOX Riveting Properties of Dissimilar Metals

Author

Wu Hui, Zhang Weiliang, and Qi Baoyun

Subjects
Materials science, fungi, technology, industry, and agriculture, Shear resistance, chemistry.chemical_element, Welding, law.invention, Corrosion, chemistry, law, Aluminium, Shear strength, Rivet, Research Object, Composite material, Joint (geology)
Abstract

The structure connection methods of steel and aluminum include mechanical connection, welding and bonding, and TOX riveting is an effective means for steel/aluminum dissimilar metal connection. The 1.5mm 5A05(0) aluminum plate and 1.5mm cold-rolled steel plate (SPCC) dissimilar metals were selected as the research object, and the steel/aluminum dissimilar metals TOX riveting tests of the different lap modes (steel plate pressed into aluminum plate, aluminum plate pressed into steel plate) were carried out under different pressures. The shear strength of the riveted joints under different pressure and lap mode was obtained, and the optimized process parameters were obtained according to the variation law of the shear strength. At the same time, the salt spray corrosion resistance of the riveted joints of steel/aluminum dissimilar metal under different treatment processes and the variation situation of joint properties after salt spray tests were studied. The test results showed that the bottom thickness decreased with the increase of pressure. When the pressure increased to 27 MPa, the change of the bottom thickness tended to be gentle, and the shear strength of the riveted joint reached the maximum. At the same pressure, the shear strength of the riveted joint when the steel plate was pressed into the aluminum plate was higher than that of the aluminum plate was pressed into the steel plate. The TOX riveted joint of steel/aluminum dissimilar metal had the best shear resistance when the steel plate was pressed into the aluminum plate at a pressure of 27 MPa. In addition, the riveted joints after painting had the best salt spray resistance, but the shear strength of the riveted joints was significantly reduced.

Published
2020

42. A 50-GHz Bandwidth Traveling-Wave Mach-Zehnder Modulator With Built-In Feedback Equalization.

Author

Gao, Jing, Zhu, Kehan, and Wu, Hui

Abstract

A 50–GHz bandwidth traveling-wave Mach-Zehnder modulator (TWMZM) was designed with a new equalization technique, which takes advantage of the intrinsic delay in a traveling-wave electrode (TWE) and a local negative-feedback circuit. With this idea, given the availability of flip-chip bonding, a long TWE can be equalized as a single stage or be segmented into a few stages, each being equalized separately to optimize the performance of the entire device. The detailed analysis of this equalization technique is presented. As a demonstration, a 1.6–mm long equalized TWMZM was designed using a commercial silicon photonic process and a 0.13 $\mu \mathrm{m}$ SiGe process. A 2–stage cascaded design with equal equalization was adopted and optimized for high bandwidth and high extinction ratio. The circuit was designed using the multi-physics electronic-photonic integrated circuit (EPIC) design flow we developed recently, wherein both electronic and photonic parts were modeled and the EPIC circuit was simulated for system level performance evaluation. Simulation results showed that the equalization technique increased the 3-dB EO bandwidth of the TWMZM from 28 to 50.4 GHz, an 80% increase. Large signal performance with non-return to zero signals upto 100 Gb/s was evaluated and the results showed significant improvements in the eye quality with equalization. The performance evaluation with pulse amplitude modulation (PAM)-4 signal was also carried out and the results showed successful operation at 106 Gbaud PAM-4 for the equalized TWMZM, makes it a promising candidate for future 200 Gbps-per-lambda optical transceivers. [ABSTRACT FROM AUTHOR]

Published
2022
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43. Recent Trends and Future Prospects of Neural Recording Circuits and Systems: A Tutorial Brief.

Author

Chen, Jinbo, Tarkhan, Mahdi, Wu, Hui, Noshahr, Fereidoon Hashemi, Yang, Jie, and Sawan, Mohamad

Abstract

Recent years have seen fast advances in neural recording circuits and systems as they offer a promising way to investigate real-time brain monitoring and the closed-loop modulation of psychological disorders and neurodegenerative diseases. In this context, this tutorial brief presents a concise overview of concepts and design methodologies of neural recording, highlighting neural signal characteristics, system-level specifications and architectures, circuit-level implementation, and noise reduction techniques. Future trends and challenges of neural recording are finally discussed. [ABSTRACT FROM AUTHOR]

Published
2022
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