超分辨弱旁瓣硅基超构透镜

超表面是一种空间变化的超薄纳米结构,在光学超分辨聚焦透镜或系统中已经得到广泛研究和应用。然而,随着超构透镜聚焦光斑缩小,不可避免产生大旁瓣,限制了透镜视场和应用潜力。本文提出了一种设计大数值孔径(NA=0.944)超分辨弱旁瓣超构透镜的方法。针对波长λ=632.8 nm的圆偏振光,基于硅基超表面PB相位调控,实现了超分辨弱旁瓣点聚焦超构透镜。实验证明,可以实现聚焦光斑半高全宽FWHM=0.45λ,小于衍射极限0.53λ(衍射极限为0.5λ/NA),旁瓣比Sidelobe Ratio(SR)=0.07。该透镜的应用有望实现超分辨光学器件或系统微型化、轻量化和集成化。     

MEMS压电阵列振动能量收集器

近年来,随着微能源的发展,微型压电振动能量收集器得到了广泛关注,但传统d31模式PZT薄膜微型压电振动能量收集器输出电压普遍较低,难以满足应用需求。为提高微型压电振动能量收集器的输出电压,论文提出了共质量块悬臂梁阵列压电振动能量收集器新结构,该结构包含压电悬臂梁单元组成的阵列和一个质量块,悬臂梁阵列共用质量块。采用有限元方法对该结构进行了优化设计,得到压电悬臂梁单元优化尺寸为3 mm×2.4 mm×0.05 mm,硅质量块优化尺寸为8 mm×12.4mm×0.5 mm。设计了MEMS压电阵列振动能量收集器加工工艺流程,加工出原理样件。在1 gn加速度,239.7 Hz谐振频率激励下,测试得到样件输出开路电压有效值为9.16 V;在最优化负载200 kΩ下,负载输出电压有效值为5.51 V,输出功率为151.8μW。     

Thick SU8 microstructures prepared by broadband UV lithography and the applications in MEMS devices

Thick SU8 microstructures with high aspect ratio and good side wall quality were fabricated by ultraviolet (UV) lithography, and the processing parameters were comprehensively studied. It proves that the adhesion of SU8 on silicon (Si) substrates is influenced by Si-OH on the surface, and can be improved by the HF treatment. Cracks and delamination are caused by large internal stress during fabrication process, and are significantly influenced by soft bake and post-exposure bake processes. The internal stress is reduced by a low post-exposure bake exposure temperature of 85 °C for 40 min. A three-step soft bake enhances the reflowing of SU8 photoresist, and results in uniform surface and less air bubbles. The vertical side wall is obtained with the optimized exposure dose of 800 mJ/cm2 for the thickness of 160 µm. Using the optimized fabrication process combined with a proper structure design, dense SU8 micro pillars are achieved with the aspect ratio of 10 and the taper angle of 89.86°. Finally, some possible applications of SU8 in micro-electromechanical system (MEMS) device are developed and demonstrated.     

光学超分辨平面超构透镜研究进展

从光学自身机理上突破光学理论分辨率极限,实现远场超分辨光学点扩散函数,进而实现超分辨聚焦和超分辨成像,在激光加工、超分辨光学显微和超分辨望远等系统有着重要应用前景.近年来,光学超构表面的发展使得在亚波长尺度上实现光场振幅、相位及偏振的独立调控成为可能,为研制新型的超分辨平面超构透镜提供了更加灵活的手段.本文介绍了基于光学超构表面的超分辨平面超构透镜、相关测试技术方面几年来的研究进展,并讨论了该领域面临的问题和未来的研究重点和方向.     

压电振动式发电机微电源智能控制应用电路的设计

针对压电振动式发电机、微型电磁感应发电机、驻极体发电机等微型发电机的发电功率较小,常规的整流滤波、存储、稳压电路不能满足瞬时发射功率较大的负载供电需求问题,提出一种微功耗的电源智能管理电路的设计方案,从而使持续的微能源得以合理而有效的利用。其主要由整流滤波电路、MOS开关及控制电路、存能电路、辅助能量补充回路和主控制电路等构成。这里以该电路在压电振动式发电机的应用为例。实验证明该电路自身的功耗只有40μw以下,能较好地满足微功耗电子器件、传感器或间歇式较大功耗无线传感网络供电的要求。