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2022-11-28
PIER
Vol. 176, 45-53, 2023
download: 42
Commercial-Printed-Circuitry-Compatible Self-Superhydrophobic Antennas Based on Laser Direct Writing
Xiao-Liang Ge Jun-Hao Yang Hang Ren Zhi-Jun Qin Qi-Dai Chen Dong-Dong Han Yong-Lai Zhang Su Xu Hong-Bo Sun
Antennas are essential devices to build everything connected in the era of information. However, the quality of communications would be degraded with the presence of raindrops on the antenna surface. Additional antiwater radomes may generate radiation loss and dispersive impedance mismatch over a broad frequency range, which is not acceptable for next-generation communication systems integrating multiple bands. Here, we report the first experimental demonstration of self-hydrophobic antennas that cover the bands of 1.7 GHz, 3.5 GHz, and 8.5 GHz through a laser-direct-writing treatment. Experimental results show that the return loss, radiation pattern, and efficiency of self-superhydrophobic antennas can be maintained in the mimicked rainy weather. Furthermore, writing hydrophobic nanostructures on both dielectrics and metals is compatible with commercial printed circuitry techniques widely used in industries. Our technique will augment the laser fabrication technology for specialized electromagnetic devices and serve as a powerful and generalized solution for all-weather wireless communication systems.
Commercial-printed-circuitry-compatible Self-superhydrophobic Antennas Based on Laser Direct Writing
2022-11-27
PIER
Vol. 176, 35-44, 2023
download: 35
Highly Transparent Tunable Microwave Perfect Absorption for Broadband Microwave Shielding
Dongdong Li Xiaojun Hu Bingtao Gao Wen-Yan Yin Hongsheng Chen Haoliang Qian
To shield undesirable microwave radiation to protect electronic systems and human health, microwave perfect absorbers have attracted increasing interests in recent years. However, the opaque or semitransparent nature of most implemented microwave absorbers limit their applications in optics. Here, we demonstrate a high-performance microwave absorber based on an impedance-assisted Fabry-Pérot resonant cavity with an ITO-dielectric-ITO structure without complex nanofabrication. The device features near-unity absorption (99.5% at 14.4 GHz with a 4.5 GHz effective bandwidth), excellent electromagnetic interference shielding performance (24 dB) in the Ku-band, and high optical transparency (89.0% from 400 nm to 800 nm). The peak absorption frequency of the device can be tuned by changing the thickness of glass slab and sheet resistance of ITO films. Our work provides a low-cost and feasible solution for highperformance optically transparent microwave shielding and stealth, paving the way towards applications in areas of microwave and optics.
Highly Transparent Tunable Microwave Perfect Absorption for Broadband Microwave Shielding
2022-11-26
PIER
Vol. 176, 25-33, 2023
download: 63
Optical Neural Networks for Holographic Image Recognition (Invited Paper)
Yiming Feng Junru Niu Yiyun Zhang Yixuan Li Hongsheng Chen Haoliang Qian
Inspired by neural networks based on traditional electronic circuits, optical neural networks (ONNs) show great potential in terms of computing speed and power consumption. Though some progress has been made in devices and schemes, ONNs are still a long way from replacing electronic neural networks in terms of generalizability. Here, we present a complex optical neural network (cONN) for holographic image recognition, within which a high-speed parallel operating unit for complex matrices is proposed, targeting the real-imaginary-splitting and column splitting. Based on the proposed cONN, we have numerically demonstrated the training-recognition process on our cONN for holographic images converted from handwritten digit datasets, achieving an accuracy of 90% based on the back-propagation algorithm. Our training verification integrated architecture will enrich the further development and applications of on-chip photonic matrix computing.
Optical Neural Networks for Holographic Image Recognition (Invited Paper)
2022-10-31
PIER
Vol. 176, 11-23, 2023
download: 218
Optically Transparent and Mechanically Flexible Coplanar Waveguide-Fed Wideband Antenna Based on Sub-Micron Thick Micro-Metallic Meshes
Jing Pan Yuanqing Yao Liu Yang Hui Li Sailing He
An optically transparent and flexible coplanar waveguide (CPW)-fed wideband antenna is proposed and demonstrated experimentally based on sub-micron thick micro-metallic meshes (μ-MMs). Due to the high visible transmittance (83.1%) and low sheet resistance (1.75 Ω/sq) of the silver μ-MM with thickness of only 190 nm, the transparent CPW has very low insertion loss and provides a good feed to the high-performance transparent antenna. The measured S11 spectrum of our antenna matches well with that of the opaque counterpart. The measured fractional bandwidth is 22% from 3.4 to 4.25 GHz. Based on numerical modeling, whose accuracy is experimentally verified, the radiation efficiency and the peak gain of our transparent antenna at 3.45 GHz are calculated to be 89.7% and 3.03 dBi, respectively. Besides the good optical and electromagnetic properties, our transparent antenna is also highly flexible. Despite the sub-micron thick μ-MMs, the transparency, radiation efficiency and mechanical properties of our transparent antenna are obviously superior to those of the transparent antennas reported previously, and the overall size and radiation gain are also comparable. Therefore, our transparent antenna has an excellent comprehensive performance, showing great potential for practical applications as well as the emerging applications in the field of flexible and wearable electronics.
Optically Transparent and Mechanically Flexible Coplanar Waveguide-fed Wideband Antenna Based on Sub-micron Thick Micro-metallic Meshes
2022-10-29
PIER
Vol. 176, 1-10, 2023
download: 204
Exceptional Ring by Non-Hermitian Sonic Crystals
Bing-Bing Wang Yong Ge Shou-Qi Yuan Ding Jia Hong-Xiang Sun
Exceptional point (EP) and exceptional ring (ER) are unique features for non-Hermitian systems, which have recently attracted great attentions in acoustics due to their rich physical significances and various potential applications. Despite the rapid development about the study of the EP and ER in one-dimensional acoustic systems, the realization of them in two-dimensional (2D) non-Hermitian structures is still facing a great challenge. To overcome this, we numerically and theoretically realize an ER in 2D reciprocal space based on a square-lattice non-Hermitian sonic crystal (SC). By introducing radiation loss caused by circular holes of each resonator in a Hermitian SC, we realize the conversion between a Dirac cone and the ER. Based on the theoretical analysis with the effective Hamiltonian, we obtain that the formation of the ER is closely related to different radiation losses of dipole and quadrupole modes in the resonators. Additionally, in the non-Hermitian SC, two eigenfunctions can be merged into a single self-orthogonal one on the ER, which does not exist in the Hermitian SC. Finally, by verifying the existence of the EP in every direction of 2D reciprocal space, we further demonstrate the ER in the proposed non-Hermitian SC. Our work may provide theoretical schemes and concrete methods for designing various types of non-Hermitian acoustic devices.
Exceptional Ring by Non-Hermitian Sonic Crystals