A MEMS VOA Using Electrothermal Actuators

A comprehensive study of electrothermally driven microelectromechanical system (MEMS) variable optical attenuator (VOA) devices using an H-shaped structure is presented in this paper. Based on its unique structural design, a retroreflection-type VOA of smaller footprint is realized. The repeatability and stability of the static and transient characteristics of attenuation behavior at various ambient temperatures are characterized. The fluctuation of attenuation curves under the same driving voltage at the same ambient temperatures is less than plusmn0.1 dB. Again, comparing the attenuation curves measured at 25 degC to 75 degC and at 25 degC to 12.5 degC, the deviation of attenuation under the same driving voltage is within the 0.6-dB range. Within the 40-dB attenuation range, the measured switching time from nonattenuation state to a particular attenuation state or between two attenuation states is less than 10 ms. This electrothermally actuated MEMS VOA also demonstrates the state-of-the-art dynamic attenuation stability that complies with the Telecordia GR1221 regulations, where the dynamic fluctuation of attenuation at 20 dB is less than plusmn0.36 dB under a vibration testing condition of 20 G periodical shocks with frequency from 20 Hz to 2 kHz     

Low-Loss Ku-Band Artificial Transmission Line With MEMS Tuning Capability

An artificial transmission line unit cell is presented based on the so-called composite right/left handed transmission line. It is implemented on a microelectromechanical system process on glass, and is suitable for applications such as reconfigurable leaky-wave antennas and series feed networks. The device presents state-of-the-art performance in terms of differential phase shift over losses (38$^{circ}/{rm dB}$ at 14 GHz) and quasi-zero drive power consumption. It is monolithic and has a total footprint of 4 ${rm mm}^{2}$.      

Secure Integration of Asymmetric and Symmetric Encryption Schemes

This paper presents a generic conversion from weak asymmetric and symmetric encryption schemes to an asymmetric encryption scheme that is chosen-ciphertext secure in the random oracle model. Our conversion is the first generic transformation from an arbitrary one-way asymmetric encryption scheme to a chosen-ciphertext secure asymmetric encryption scheme in the random oracle model.     

Tunable Dielectric Resonator Bandpass Filter With Embedded MEMS Tuning Elements

This paper presents a novel approach for constructing a tunable dielectric resonator bandpass filter by using the microelectromechanical system (MEMS) technology. The tunability is achieved by unique MEMS tuning elements to perturb the electrical and magnetic fields surrounding the dielectric resonators. The use of such elements as a tuning mechanism results in a wide tuning range at a relatively low tuning voltage and fast tuning speed. A three-pole tunable dielectric resonator bandpass filter is designed, fabricated, and tested. The experimental filter has a center frequency of 15.6 GHz, a 1% relative bandwidth, and an unloaded Q of 1300. A tuning range of 400 MHz is obtained by using MEMS tuning elements with 2 mmtimes2 mm tuning disks. The measured results demonstrate the feasibility of the proposed concept     

基于MEMS的新型高场不对称波形离子迁移谱仪

简要回顾了离子迁移谱技术的发展历程,叙述了常规离子迁移谱的局限性。阐述了基于MEMS工艺的新型高场不对称波形离子迁移谱技术,该技术以物质离子的离子迁移率在高场下的非线性变化特性为基础,可实现对物质离子的空间分离。以MEMS技术为主体,自主研发了高场不对称波形离子迁移谱仪,并对挥发性有机物、苯系物、爆炸物和农药等样品进行了检测,结果表明该离子迁移谱仪能够对苯、丙酮、对二甲苯、爆炸物梯恩梯和农药硫丹等物质实现快速、高分辨和高灵敏度检测,检测精度达10-9量级,线性度达0.95。该结果展示了其在物质离子分离检测方面的巨大潜力,以及在环境、食品安全和生物大分子等领域的优越性和前景,其研究成果将推动下一代物质离子分离检测技术的发展。     

调谐范围达40nm的电泵浦1.5μm MEMS VCSEL

德国Technische大学和Two-Chip Photonics AG公司的科学家们合作研制出一种调谐范围在40nm的电泵浦垂直腔面发射激光器(VCSEL)。该激光器以单模形式输出1553～1595nm波长的激光，是迄今报道过的同类产品中调谐范围最宽的。该激光器不仅在通信而且在微量气体测量、计量学、过程控制和医学诊断等领域有着重要应用。     

Global Synchronization and State Tuning in Asymmetric Complex Dynamical Networks

A strategy to control the complex dynamical networks for global synchronization as well as to tune their synchronous states is presented based on linear state feedback controllers. The synchronous state can be changed from one system to other similar system just by choosing a suitable tuning matrix. Especially, some of the criteria are expressed in normal inequalities instead of matrix inequalities. Simulations are also done to verify the theoretical results.      

单双钥混合体制的选择密文安全性

该文主要讨论单双钥混合体制的选择密文安全性IND-CCA的定义和相关结论。在对两种不同用途的单双钥混合体制及其安全性的研究之后发现它们的IND-CCA定义中允许敌手访问的预言机不同,我们将其统一为：对只能询问混合体制整体解密机的敌手的安全性,从而统一了混合体制的安全结论,为正确使用混合体制提供了依据。我们提出了一种混合体制：REACT+,并证明了其IND-CCA安全性。     

Retro-Axial VOA Using Parabolic Mirror Pair

This letter presents a design of a microelectromechanical systems variable optical attenuator (VOA) that employs a pair of parabolic mirrors as the retro-reflector, which has obtained a linear relationship over a 62-dB range between the attenuation (in decibels) and the mirror rotation angle (in degrees). The insertion loss measures 0.6 dB thanks to the three-dimentional optical coupling design. The linearity comes from the simultaneous shift and defocus of the laser beam. Compared with the conventional coaxial and cross-axial VOAs, such retro-axial design has the two fibers arranged on the same side and thus facilitates the use of standard packaging formats     

基于液晶技术的光可变衰减器研究

基于液晶的电控双折射特性,从光路上设计了液晶光可变衰减器(VOA),并详细分析了其工作原理;用琼斯矩阵理论推导了其光传输矩阵,得出了光功率衰减与电压关系的表达式,并在理论上进行了仿真;最后对其进行了实验研究,实验数据与理论分析相吻合。     

Over 15% Efficiency Polymer Solar Cells Enabled by Conformation Tuning of Newly Designed Asymmetric Small‐Molecule Acceptors

The prosperous period of polymer solar cells (PSCs) has witnessed great progress in molecule design methods to promote power conversion efficiency (PCE). Designing asymmetric structures has been proved effective in tuning energy level and morphology, which has drawn strong attention from the PSC community. Two hepta‐ring and octa‐ring asymmetric small molecular acceptors (SMAs) (IDTP‐4F and IDTTP‐4F) with S‐shape and C‐shape confirmations are developed to study the relationship between conformation shapes and PSC efficiencies. The similarity of absorption and energy levels between two SMAs makes the conformation a single variable. Additionally, three wide‐bandgap polymer donors (PM6, S1, and PM7) are chosen to prove the universality of the relationship between conformation and photovoltaic performance. Consequently, the champion PCE afforded by PM7: IDTP‐4F is as high as 15.2% while that of PM7: IDTTP‐4F is 13.8%. Moreover, the S‐shape IDTP‐4F performs obviously better than their IDTTP‐4F counterparts in PSCs regardless of the polymer donors, which confirms that S‐shape conformation performs better than the C‐shape one. This work provides an insight into how conformations of asymmetric SMAs affect PCEs, specific functions of utilizing different polymer donors to finely tune the active‐layer morphology and another possibility to reach an excellent PCE over 15%.     

调谐泵浦的微型YAG激光及其温度调谐

用730至830nm调谐的钛兰宝石激光纵向泵浦微型YAG激光,最大连续输出为216mW,斜率效率为30％。改变YAG的工作温度从5℃到100℃,其输出波长从1.06398μm调谐至1.064541μm。随着温度的上升,输出功率下降。     

MEMS的前景

微机电系统(MEMS)在研究领域已经有很长历史了,但一直没有真正进入大规模产业化阶段.而现在将硅芯片和微机械结构结合在一起的光学元件为MEMS带来新的商业机会.MEMS热了起来,各种新起步的MEMS公司开始吸引大量的风险资金.一些在此领域已经发展了数年的公司宣称自己开始得到回报,甚至已经赢利.但业内人士认为MEMS元件仅仅是刚开始从实验室走向实用,对许多半导体公司来说,MEMS业务最终能否取得成功的关键在于他们如何充分利用在IC方面获得的设计、制造和市场经验.     

微波微电子机械开关

介绍了微波微电子机械开关(MEMS开关)的形式、物理特性,分析了其工作原理.文中采用一端固定、一端自由运动的悬臂梁的力学模型,给出了MEMS开关设计的经验公式.最后,对微电子机械开关在MMIC中的发展前景作出了预测.     

基于SOI的低功耗低偏振相关损耗的可调光衰减器

基于硅的等离子体色散效应,构建了大尺寸SOI基光波导电光可调光衰减器(VOA)仿真模型,系统模拟分析了结构参数对VOA衰减及偏振相关特性的影响,优化设计出了低功耗、低偏振相关损耗的VOA器件,仿真结果表明,该VOA在20 dB衰减下的功耗仅为24 mW,偏振相关损耗为0.41 dB.     

MEMS switches

Microelectromechanical system (MEMS) microswitches are receiving increasing attention, particularly in the RF community. Low power consumption, low insertion loss, high isolation, excellent linearity, and the ability to be integrated with other electronics all make microswitches an attractive alternative to other mechanical and solid-state switches. This article features a newly developed, surface micromachined, electrostatically actuated direct metal-to-metal microswitch which can be used in applications from dc through microwave.     

Micro MEMS

RF Micro Devices Inc has shipped its 250m power amplifier (PA) module.This is a short news story only. Visit www.three-fives.com for the latest advanced semiconductor industry news.     

Marvelous MEMS

Microelectromechanical systems (MEMS) are a foundation for a broad range of mechanical, chemical, optical, and biotech products (sensors, microstructures and actuators) fabricated as integrated circuits on (primarily) silicon wafers in a batch mode. Commercial MEMS products include pressure sensors, acceleration sensors, gyros, ink-jet nozzles, read-write head positioners in hard drives, and digital light processors (DLPs) in projectors and television sets. The first four decades of MEMS development created a US$8 billion market. During the next decade, the MEMS market is estimated to increase by US$32 billion. Based on the presented overview of emerging MEMS sensors and microstructures, such a magnitude of growth is definitely possible.