查看更多>>摘要：Metalenses with achromatic performance offer a new opportunity for high-quality imaging with an ultra-compact configuration;however,they suffer from complex fabrication processes and low focusing effi-ciency.In this study,we propose an efficient design method for achromatic microlenses on a wavelength scale using materials with low dispersion,an adequately designed convex surface,and a thickness profile distribution.By taking into account the absolute chromatic aberration,relative focal length shift(FLS),and numerical aperture(NA),microlens with a certain focal length can be realized through our realized map of geometric features.Accordingly,the designed achromatic microlenses with low-dispersion fused silica were fabricated using a focused ion beam,and precise surface profiles were obtained.The fabricated microlenses exhibited a high average focusing efficiency of 65％at visible wavelengths of 410-680 nm and excellent achromatic capability via white light imaging.Moreover,the design exhibited the advan-tages of being polarization-insensitive and near-diffraction-limited.These results demonstrate the effec-tiveness of our proposed achromatic microlens design approach,which expands the prospects of miniaturized optics such as virtual and augmented reality,ultracompact microscopes,and biological endoscopy.
查看更多>>摘要：In three-dimensional(3D)stacking,the thermal stress of through-silicon via(TSV)has a significant influ-ence on chip performance and reliability,and this problem is exacerbated in high-density TSV arrays.In this study,a novel hollow tungsten TSV(W-TSV)is presented and developed.The hollow structure pro-vides space for the release of thermal stress.Simulation results showed that the hollow W-TSV structure can release 60.3％of thermal stress within the top 2 pm from the surface,and thermal stress can be decreased to less than 20 MPa in the radial area of 3 pm.The ultra-high-density(1600 TSV·mm-2)TSV array with a size of 640 x 512,a pitch of 25 pm,and an aspect ratio of 20.3 was fabricated,and the test results demonstrated that the proposed TSV has excellent electrical and reliability performances.The average resistance of the TSV was 1.21 Ω.The leakage current was 643 pA and the breakdown voltage was greater than 100 V.The resistance change is less than 2％after 100 temperature cycles from-40 to 125 ℃.Raman spectroscopy showed that the maximum stress on the wafer surface caused by the hollow W-TSV was 31.02 MPa,which means that there was no keep-out zone(KOZ)caused by the TSV array.These results indicate that this structure has great potential for applications in large-array photodetectors and 3D integrated circuits.
查看更多>>摘要：A substantial reduction in groundwater level,exacerbated by coal mining activities,is intensifying water scarcity in western China's ecologically fragile coal mining areas.China's national strategic goal of achiev-ing a carbon peak and carbon neutrality has made eco-friendly mining that prioritizes the protection and efficient use of water resources essential.Based on the resource characteristics of mine water and heat hazards,an intensive coal-water-thermal collaborative co-mining paradigm for the duration of the min-ing process is proposed.An integrated system for the production,supply,and storage of mining compan-ion resources is achieved through technologies such as roof water inrush prevention and control,hydrothermal quality improvement,and deep-injection geological storage.An active preventive and con-trol system achieved by adjusting the mining technology and a passive system centered on multi-objective drainage and grouting treatment are suggested,in accordance with the original geological char-acteristics and dynamic process of water inrush.By implementing advanced multi-objective drainage,specifically designed to address the"skylight-type"water inrush mode in the Yulin mining area of Shaanxi Province,a substantial reduction of 50％in water drillings and inflow was achieved,leading to stabilized water conditions that effectively ensure subsequent safe coal mining.An integrated-energy complementary model that incorporates the clean production concept of heat utilization is also proposed.The findings indicate a potential saving of 8419 t of standard coal by using water and air heat as an alter-native heating source for the Xiaojihan coalmine,resulting in an impressive energy conservation of 50.2％and a notable 24.2％reduction in carbon emissions.The ultra-deep sustained water injection of 100 m3·h-1 in a single well would not rupture the formation or cause water leakage,and 7.87 x 105 t of mine water could be effectively stored in the Liujiagou Formation,presenting a viable method for mine-water management in the Ordos Basin and providing insights for green and low-carbon mining.
查看更多>>摘要：In this paper,a hybrid integrated broadband Doherty power amplifier(DPA)based on a multi-chip mod-ule(MCM),whose active devices are fabricated using the gallium nitride(GaN)process and whose pas-sive circuits are fabricated using the gallium arsenide(GaAs)integrated passive device(IPD)process,is proposed for 5G massive multiple-input multiple-output(MIMO)application.An inverted DPA structure with a low-Q output network is proposed to achieve better bandwidth performance,and a single-driver architecture is adopted for a chip with high gain and small area.The proposed DPA has a bandwidth of 4.4-5.0 GHz that can achieve a saturation of more than 45.0 dBm.The gain compression from 37 dBm to saturation power is less than 4 dB,and the average power-added efficiency(PAE)is 36.3％with an 8.5 dB peak-to-average power ratio(PAPR)in 4.5-5.0 GHz.The measured adjacent channel power ratio(ACPR)is better than-50 dBc after digital predistortion(DPD),exhibiting satisfactory linearity.
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