基于1665 nm激光器测量甲烷气体浓度的研究

介绍了一种以1665 nm分布反馈(DFB)激光器为光源,使用双光路差分吸收光谱技术(DAS)测量甲烷浓度的检测系统。双光路差分吸收光谱技术能有效抑制由于光源光强变化、探测器零点漂移等因素所引起的测量的不准确。文中对这种检测方法进行了理论和实验分析,系统的最小探测浓度为100×10-6,响应时间约为14 s。     

基于压缩感知的自适应数字波束形成算法

该文根据目标在空间的稀疏性,提出了接收端的基于压缩感知理论的自适应数字波束形成算法.在阵元稀布的情况下,用压缩感知的压缩采样理论,恢复出缺失通道的回波信息,然后用恢复的信号做数字波束形成.该算法所形成的波束具有波束旁瓣低,指向误差小,干扰方向零陷深,而且没有栅瓣等优点,波束性能接近满阵时候的波束性能,而且使用该方法减少的阵元数远远大于其他稀布阵方法减少的阵元数.采用蒙特卡罗方法对该方法进行了性能评估,给出了不同信噪比、不同干噪比、不同快拍情况下的计算结果,仿真结果也验证了该算法的正确性.     

双简支梁结构光纤光栅加速度传感探头的设计

采用双简支梁结构设计了一种光纤光栅加速度传感探头,探头弹性系统由双简支梁、双光纤光栅、质量块等组成。采用差动补偿法解决了光纤光栅传感器温度与应变交叉敏感问题。该探头结构简单,线性度好,一阶谐振频率达到525Hz,不受电磁干扰,不受光路功率波动和相位噪声影响,且测量灵敏度是单光纤光栅传感器的2倍。     

Principles and realizations of FBG wavelength tuning with elastic beams

FiberBragggrating(FBG)isasignificanttechnology thatisusedtodesignkeydevicesorcomponentsinthesystemsoffibercommunicationandfibersensing[1], suchastunablefiberlasers[2],WDW/DM[3],WADM[4],tunablefiberfilter[5],fiberdispersioncom pensation[6],gainflattingofEDFA[7],FBG typeinter ferometer[8]andfibergratingsensors[9,10].OneofthekeyresearchissuesonFBGdevicesistomakethetun ingwavelengthdeviceswhichhavegoodcharacteristics ofwidetunablewavelengthrange,stableoutput,goodmultiplexingcapability. …     

Generation of dual beams from spherical phased array antenna

An active X-band spherical phased array developed for transmitting high bit rate data from remote sensing satellites to two ground stations simultaneously is presented. Resolution of the dual phase adjustment of the phase shifters, which are common to generate two beams, is discussed.     

直接输出的超短脉冲轨道角动量涡旋光产生技术研究进展（特邀）

轨道角动量（OAM）涡旋光是一种具有相位孤立奇点的光场,其相位波前呈螺旋分布,光场复振幅包含螺旋相位项exp(ilθ)。近年来,OAM涡旋光被广泛地应用在光学操控、成像、通信、传感等方面。超短脉冲OAM涡旋光同时具有涡旋光和超短脉冲的优点,可应用于手性材料加工、远距离传输、强场物理研究,非线性频率转换研究等方面。通过激光器直接产生OAM涡旋光具有系统整体简便性高和光束质量好等优势,对国内外基于有源方法产生超短OAM涡旋光的方法进行了总结。目前,通过有源方式产生的超短OAM涡旋光的脉冲宽度还局限于几百飞秒,如何通过直接输出的方法获得百飞秒以内甚至是少周期脉冲涡旋光输出将是未来研究的一个重要方向。     

压电智能应用于柔性悬臂梁振动控制系统研究

基于模糊控制的振动控制方法,针对柔性悬臂梁,设计了相应振动控制器。采用电桥电路法分离出压电自感知执行器的感知信号,通过传感器将采集进来的信号,由最优控制理论离线计算得到理论输出值。并将理论输出值与对应的系统输入值对应起来,从而建立拥有最优解的模糊控制规则表。通过传感器采集系统状态并经过处理得到输出信号,作用于执行器上对柔性梁的振动进行抑制。仿真结果表明,采用的控制器对于改善振动快速控制是非常有效的。     

基于光纤自适应操控的激光相控阵技术研究进展(特邀)

当前,基于多光束相干合成的激光相控阵技术面临着实际湍流环境下远距离传输的应用需求和挑战,需同时校正系统内部光源噪声和外部动态湍流像差,并解决远距离传输光延迟和系统规模增大导致的有效带宽急剧下降的问题。现有的技术手段如目标在回路技术和延迟SPGD算法无法应对湍流带来的动态倾斜像差,而这一点对在远场目标处获得高质量相干合成光束至关重要。文中介绍了中国科学院光电技术研究所在多孔径激光传输控制技术上的最新研究进展,新技术实现了对光纤阵列激光出射光束倾斜像差的并行和高效校正,并提出了基于主动波前测量的光纤激光阵列外部像差预补偿校正的方法,为光纤激光相控阵技术的实际大气传输应用打下基础。     

Fabrication and characterization of a microelectromechanical tunable capacitor

A micromechanical tunable capacitor fabricated using the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-process has been investigated in this study. The structure of the tunable capacitor consists of a membrane, supported beams, driving and sensing electrodes. The membrane is sustained by the supported beams. The tunable capacitor requires only one wet etching post-process to release the suspended structures. The post-process has the advantages of easy execution and low cost. The tunable capacitor contains a driving part and a sensing part. The sensing part generates a change in capacitance when applying a driving voltage to the driving part. Experimental results show that the tunable capacitor has a capacitance of 1.38 pF, a tuning range of 85% and a Q-factor of 40 at 100 MHz.     

多光束照明方式对平滑光强起伏效果的影响研究

基于多光纤耦合输出半导体激光作为照明光源的主动成像系统比较了多束非相干聚焦光束和准直光束平滑光强起伏的效果,分析了两种光束受湍流引起的光束短期扩展和束心抖动的异同,为多光束照明方式提供了参考。采用相位屏近似方法模拟激光大气传输,模拟结果表明对这种主动成像系统采取准直发射方式可以有效平滑光强起伏,而聚焦发射方式则不能实现此目的。     

Coherent Control of Wave Beams Via Unidirectional Evanescent Modes Excitation

Conventional coherent absorption occurs only when two incident beams exhibit mirror symmetry with respect to the absorbing surface, i.e., the two beams have the same incident angles, phases, and amplitudes. This study proposes a more general metasurface paradigm for coherent perfect absorption with impinging waves from arbitrary asymmetric directions. By exploiting excitation of unidirectional evanescent waves, the output can be fixed at one reflection direction for any amplitude and phase of the control wave. It shows theoretically and confirm experimentally that the relative amplitude of the reflected wave can be tuned continuously from zero to unity by changing the phase difference between the two beams, i.e., switching from coherent perfect absorption to full reflection. It hopes that this study will open up promising possibilities for wave manipulation via evanescent waves engineering with applications in optical switches, optical computing, one-side sensing, photovoltaics, and radar cross-section control.     

Fiber-coupled in-line heterodyne optical interferometer for minimally invasive sensing

In this paper, the first fiber-coupled no-moving-parts scanning heterodyne interferometer design using a single acoustooptic device (AOD) is reported. The design features a high-stability inline reflective architecture with free-space-scanned minimally invasive sensing via a multizone reflective sensor chip. The common path fiber interconnection allows robust remoting of the compact sensing front end. A proof-of-concept sensing experiment measuring voltage-dependent birefringence is successfully conducted using a voltage-controlled nematic liquid crystal (NLC) sensor chip. The system features a 4.69-dB optical loss, a 200-MHz output frequency, and a 1550-nm eye-safe operation wavelength. Applications for the system include any fiber-remoted sensing using the proposed free-space minimally invasive interrogating optical beams.     

Simulation and fabrication of HF microelectromechanical bandpass filter

A high-frequency (HF) micromechanical bandpass filter fabricated using the commercial 0.35 μm complementary metal oxide semiconductor (CMOS) process and the post-process has been investigated in this study. The area of the filter is about 150×200 μm². The filter is composed of two resonators, which are joined by a coupling beam. Each resonator contains a membrane, four supported beams and two fixed electrodes, and the membrane is supported by four supported beams. The filter requires a post-process to etch the sacrificial layer, and to release the suspended structures. The post-process needs only one wet etching to etch silicon dioxide layer. The filter contains a sensing part and a driving part. When applying a driving voltage to the driving part, the sensing part generates a change in capacitance. The capacitance variation of the sensing part is converted into the output voltage by a sensing circuitry. Experiments show that the filter has a center frequency of about 39.6 MHz and a bandwidth of 330 kHz.     

The Sagnac interferometer as a two-parameter sensor

We show the Sagnac interferometer as a two-parameter sensing device where nonreciprocal and reciprocal effects can be independently and simultaneously monitored. Phase shifts induced by nonreciprocal effects affect differently the counterpropagating beams in the loop and are accurately detected by a phase sensitive detection scheme. A probe for reciprocal effects is built by introducing a birefringence modulator inside the polarization-maintaining loop with its axes rotated with respect to the axes of the loop fiber. The resulting quadrature component of the demodulated signal is proportional to the phase shift induced by reciprocal effects at the probe site, making the interferometer suitable for dual parameter sensing. Demonstration of a electric/magnetic field sensor is presented     

Phase‐Responsive Fourier Nanotransducers for Probing 2D Materials and Functional Interfaces

Light scattered by an object contains plethora information about the object which is distributed evenly among all possible Fourier components of light observed in the far‐field. There are some cases, however, where this information is accumulated in the light confined by the object and then encoded in just a few coherent optical beams. Here, Fourier nanotransducers based on 2D plasmonic metamaterials are introduced, which are capable of confining light in 2D plane contacting with a functional interface, gathering information about its properties, and then transmitting the information into discrete optical beams with amplified phase relations. It is shown that phase of light in such beams can be used for probing dynamic physical properties of 2D materials and performing bio/chemical sensing with unprecedented sensitivity. Using a Fourier transducer based on periodic gold nanostructures, ferroelectric response from a single atomic layer of MoS₂ is resolved and studied for the first time, as well as the detection of important antibiotic chloramphenicol at fg mL^?1 level is demonstrated, which several orders of magnitude better than reported in the literature. The implementation of phase‐responsive Fourier nanotransducers opens new avenues in exploration of emergent 2D structures and radical improvement of biosensing technology.     

光子晶体光纤光栅制备方法最新进展

详细阐述了国内外几种典型光子晶体光纤光栅的制备方法，如紫外曝光法、热激成栅法、机械压力法、双光子吸收法．并分析了各自的优缺点，还分析了光子晶体光纤布拉格光栅、长周期光栅的模式耦合特性。研究表明：光子晶体光纤光栅具有对外界折射率不敏感的特性，且在纯硅纤芯写制的光栅还具有对温度不敏感的特性。简要介绍了光子晶体光纤光栅在光通信及光传感领域中的应用，并对基于光子品体光纤光栅的新型光子器件进行了展望。     

采用深度学习校正畸变涡旋光束的方法综述(特邀)

涡旋光束是一种携带轨道角动量的新型结构光场,在超大容量光通信、遥感探测等领域有着广阔的应用前景。涡旋光束在大气等非均匀介质中传输时会产生波前畸变,使得其携带的轨道角动量发生改变,对实际应用产生不利影响,因此需要引入自适应光学波前校正技术对其进行畸变校正。综述了近年来国内外学者在涡旋光束自适应畸变校正方面的研究进展,首先简要介绍了当前较为成熟的涡旋光束畸变校正技术,包括高斯光束探针与波前传感相结合、相位恢复算法与面阵探测技术相结合等技术方案;然后着重介绍了基于深度学习的新型涡旋光束畸变校正技术,包括泽尼克多项式系数反演、湍流相位屏反演等,同时讨论了将深度学习用于涡旋光束畸变校正的优势及局限性;最后展望了涡旋光束自适应畸变校正技术的发展趋势。     

Computer Simulation of Axis-Encircling Beams Generated by an Electron Gun with a Permanent Magnet System

Results from computer aided design of a novel electron gun generating axis-encircling beams are presented and discussed. Numerical experiments were performed by the new version of the software package GUN-MIG named GUN-MIG/CUSP. It is based on a self-consistent relativistic model and is developed as a problem oriented tool for analysis of electron-optical systems with magnetron injection guns (MIG) and electron guns with field reversal (cusp guns), forming axis-encircling beams. As a result of the simulations an electron-optical design of a novel electron gun with permanent magnet system was accomplished. The gun is expected to form high quality beams with small velocity spread and beam ripple. Parameters of the generated beams are appropriate for a prospective weakly relativistic high harmonic large orbit gyrotron (LOG). The development of such device is in progress now at the Research Center for Development of Far-Infrared Region (FIR Center) at Fukui University.     

直接输出高阶横模激光器的实验研究

从理论和实验上研究了从激光器直接输出高阶拉盖尔-高斯（LG）光束和高阶厄密-高斯（HG）光束。首先从理论上研究了高阶LG光束和高阶HG光束的光强分布特性,并进行数值仿真。在实验研究中,利用445 nm的蓝光半导体激光器端面泵浦Pr:YLF晶体,在一定的条件下,能从平凹腔直接输出640 nm波长高阶LG光束和高阶HG光束。实验结果表明:从激光腔内输出的高阶LG光束和高阶HG光束与理论仿真基本一致。文中所报道的获得高阶模的实验装置简单,对产生高阶光束及其应用具有较重要价值。     

GaAs基共振隧穿微加速度计的研究

研究了一种新型的GaAs基压阻式共振隧穿微加速度计结构。该微加速度计的压敏元件采用AlAs/In0.1Ga0.9As双势垒共振隧穿纳米薄膜结构。加速度计的压敏元件和悬臂梁的加工分别利用空气桥工艺和控制孔工艺。对加工出来的加速度计结构进行振动台实验,初步测得传感器的灵敏度为7.6mV/g,线性度为0.16%。