为了同时实现应用于步进扫描投影光刻机中的长行程直线电机的高推力密度、低推力波动和低铜损耗,提出了基于多种群遗传算法(multiple population genetic algorithm,MPGA)的环形绕组形式无铁心永磁直线同步电机(air-corepermanent magne...为了同时实现应用于步进扫描投影光刻机中的长行程直线电机的高推力密度、低推力波动和低铜损耗,提出了基于多种群遗传算法(multiple population genetic algorithm,MPGA)的环形绕组形式无铁心永磁直线同步电机(air-corepermanent magnet linear synchronous motor,ACPMLSM)多目标优化设计方法。在建立磁场分析模型的基础上,推导了关键参数的解析表达式。以永磁体、环形绕组的尺寸为变量,以推力体积比、电机常数和推力波动为优化目标,提出了基于权重系数的多目标优化函数,应用搜索能力强、收敛速度快的多种群遗传算法优化电机的结构尺寸。结果表明,在不同的权重系数下,MPGA得到的电机优化设计结果与设计目标具有良好的一致性。有限元仿真和实验结果证明了所提方法的有效性和可行性。展开更多
Micro/nanoprocessing of graphene surfaces has attracted significant interest for both science and applications due to its effective modulation of material properties,which,however,is usually restricted by the disadvan...Micro/nanoprocessing of graphene surfaces has attracted significant interest for both science and applications due to its effective modulation of material properties,which,however,is usually restricted by the disadvantages of the current fabrication methods.Here,by exploiting cylindrical focusing of a femtosecond laser on graphene oxide(GO)films,we successfully produce uniform subwavelength grating structures at high speed along with a simultaneous in situ photoreduction process.Strikingly,the well-defined structures feature orientations parallel to the laser polarization and significant robustness against distinct perturbations.The proposed model and simulations reveal that the structure formation is based on the transverse electric(TE)surface plasmons triggered by the gradient reduction of the GO film from its surface to the interior,which eventually results in interference intensity fringes and spatially periodic interactions.Further experiments prove that such a regular structured surface can cause enhanced optical absorption(>20%)and an anisotropic photoresponse(~0.46 ratio)for the reduced GO film.Our work not only provides new insights into understanding the laser-GO interaction but also lays a solid foundation for practical usage of femtosecond laser plasmonic lithography,with the prospect of expansion to other two-dimensional materials for novel device applications.展开更多
作为当前集成电路制造的主流技术,光学光刻在趋近其分辨力极限的同时,面临着越来越大的挑战,即便在波前工程和分辨力增强技术的帮助下,光学光刻的分辨力也难以满足快速发展的半导体产业的技术需求。接近式 X 射线光刻技术(XRL)、散射角...作为当前集成电路制造的主流技术,光学光刻在趋近其分辨力极限的同时,面临着越来越大的挑战,即便在波前工程和分辨力增强技术的帮助下,光学光刻的分辨力也难以满足快速发展的半导体产业的技术需求。接近式 X 射线光刻技术(XRL)、散射角限制电子束投影光刻技术(SCALPEL)、电子束直写光刻技术(EBDW)、极紫外线即软 X 射线投影光刻技术(EUVL)、离子投影光刻技术(IPL)等下一代光刻技术(NGL)将会在特征线宽为 100—70 nm 的技术节点介入集成电路制造的主流技术中。从目前 NGL 技术发展的趋势和市场需求的多元化来看,竞争的结果很可能是各种 NGL 技术并存。当特征尺寸进入纳米尺度(≤100 nm)以后,最终只有那些原子级的成像技术才能成为胜者。展开更多
Optical true delay lines(OTDLs)of low propagation losses,small footprints and high tuning speeds and efficiencies are of critical importance for various photonic applications.Here,we report fabrication of electro-opti...Optical true delay lines(OTDLs)of low propagation losses,small footprints and high tuning speeds and efficiencies are of critical importance for various photonic applications.Here,we report fabrication of electro-optically switchable OTDLs on lithium niobate on insulator using photolithography assisted chemo-mechanical etching.Our device consists of several low-loss optical waveguides of different lengths which are consecutively connected by electro-optical switches to generate different amounts of time delay.The fabricated OTLDs show an ultra-low propagation loss of^0.03dB/cm for waveguide lengths well above 100 cm.展开更多
文摘为了同时实现应用于步进扫描投影光刻机中的长行程直线电机的高推力密度、低推力波动和低铜损耗,提出了基于多种群遗传算法(multiple population genetic algorithm,MPGA)的环形绕组形式无铁心永磁直线同步电机(air-corepermanent magnet linear synchronous motor,ACPMLSM)多目标优化设计方法。在建立磁场分析模型的基础上,推导了关键参数的解析表达式。以永磁体、环形绕组的尺寸为变量,以推力体积比、电机常数和推力波动为优化目标,提出了基于权重系数的多目标优化函数,应用搜索能力强、收敛速度快的多种群遗传算法优化电机的结构尺寸。结果表明,在不同的权重系数下,MPGA得到的电机优化设计结果与设计目标具有良好的一致性。有限元仿真和实验结果证明了所提方法的有效性和可行性。
基金financially supported by the National Natural Science Foundation of China(Grant Nos.91750205,11674178,and 11804334)the Jilin Provincial Science&Technology Development Project(Grant No.20180414019GH)the K.C.Wong Education Foundation(GJTD-2018-08).
文摘Micro/nanoprocessing of graphene surfaces has attracted significant interest for both science and applications due to its effective modulation of material properties,which,however,is usually restricted by the disadvantages of the current fabrication methods.Here,by exploiting cylindrical focusing of a femtosecond laser on graphene oxide(GO)films,we successfully produce uniform subwavelength grating structures at high speed along with a simultaneous in situ photoreduction process.Strikingly,the well-defined structures feature orientations parallel to the laser polarization and significant robustness against distinct perturbations.The proposed model and simulations reveal that the structure formation is based on the transverse electric(TE)surface plasmons triggered by the gradient reduction of the GO film from its surface to the interior,which eventually results in interference intensity fringes and spatially periodic interactions.Further experiments prove that such a regular structured surface can cause enhanced optical absorption(>20%)and an anisotropic photoresponse(~0.46 ratio)for the reduced GO film.Our work not only provides new insights into understanding the laser-GO interaction but also lays a solid foundation for practical usage of femtosecond laser plasmonic lithography,with the prospect of expansion to other two-dimensional materials for novel device applications.
基金Supported by the National Key R&D Program of China(Grant No.2019YFA0705000)the National Natural Science Foundation of China(Grant Nos.11734009,61590934,and 11874375)+1 种基金the Strategic Priority Research Program of CAS(Grant No.XDB16030300)the Key Project of the Shanghai Science and Technology Committee(Grant No.17JC1400400).
文摘Optical true delay lines(OTDLs)of low propagation losses,small footprints and high tuning speeds and efficiencies are of critical importance for various photonic applications.Here,we report fabrication of electro-optically switchable OTDLs on lithium niobate on insulator using photolithography assisted chemo-mechanical etching.Our device consists of several low-loss optical waveguides of different lengths which are consecutively connected by electro-optical switches to generate different amounts of time delay.The fabricated OTLDs show an ultra-low propagation loss of^0.03dB/cm for waveguide lengths well above 100 cm.
