光照度检测仪的设计

在公路隧道交通中,照度的测量和控制是很常见的。基于此设计一种具有自动量程转换功能、测量精度高、成本低的工控型数显照度计。本设计是以单片机ATMEGA8为核心部件的测量系统,硬件部分主要由信号采集、信号放大、A／D转换、数码显示和Rs485通讯接口几部分。整个系统软件部分主要有：传感器数据采集模块、光亮度检测模块、通讯接口模块、光亮度显示模块。通过实验测试,本系统设计合理,其测量范围、分辨率、光谱响应误差基本上达到了设计的要求。     

光照度检测仪的设计

在公路隧道交通中,照度的测量和控制是很常见的。基于此设计一种具有自动量程转换功能、测量精度高、成本低的工控型数显照度计。本设计是以单片机Atmega8为核心部件的测量系统,硬件部分主要由信号采集、信号放大、A/D转换、数码显示和RS485通讯接口几部分。整个系统软件部分主要有：传感器数据采集模块、光亮度检测模块、通讯接口模块、光亮度显示模块。通过实验测试,本系统设计合理,其测量范围、分辨率、光谱响应误差基本上达到了设计的要求。     

一种波分解复用技术的实验研究

文章提出一种基于光折变晶体LiNbO3的波分解复用技术实验研究方法,研究了影响光栅衍射效率的重要因素.实验采用o光写入e光读出,写入光强比为1∶1.通过在同一位置由红光和绿光先后写入光栅(两光栅夹角为0.18°时不会发生串扰),并用耦合光读出,成功地进行了解复用实验.     

Multi-LED package design, fabrication and thermal analysis

An ultra-thin multi-LED package is designed,manufactured and its thermal performance is characterized. The objective of this study is to develop an efficient thermal modelling approach for this system which can be used for optimization of the thermal-performance of future ultra-thin designs.A high-resolution thermal imaging camera and thermocouples were used to measure the temperature distribution of the multi-LED package and the LED-die temperature for different operating powers.Finally,we compare the thermal measurements with the finite element simulation results.It is concluded that the modelling approach can assist in the thermal optimization of future multi-LED package designs.     

An ARROW optical wavelength filter: design and analysis

A novel ARROW (antiresonant reflecting optical waveguide)-based optical wavelength filter is proposed. The modal characteristics of the coupled ARROW structures is analyzed rigorously by the transverse resonance method. As an alternative configuration to the conventional directional coupler filter, the proposed device features large core size compatible with fiber and nearly periodic dependence of the coupling-length on the waveguide separation, which provides more flexibility for fabrication of the device. A design procedure for this type of coupled ARROW structure used for wavelength filtering is presented. The devices designed are simulated and verified by the beam propagation method. An ARROW wavelength filter based on SiO₂/TiO₂ has a FWHM bandwidth narrower than 7 Å     

Guidelines for design and fabrication of fused fiber coupler based wavelength division multiplexings

The fused fiber coupler can be function as WDM (Wavelength Division Multiplexing). An analysis of the wavelength response of the fused fiber coupler is presented here. Both theoretical and numerical methods are used to calculate the wavelength channel spacing of WDM at different pulling stop cycles. Experiments were carried out to testify the calculation results. A combination of theoretical and numerical method is used to predict the channel spacing of WDM. The calculation agrees well with the experimental results. This paper provides some guidelines for design and fabrication of the fused fiber based WDMs.     

密集型多重体全息光栅波长解复用技术

阐述了光折变多重体全息光栅作为滤波器实现波长解复用的原理,分析了滤波器的波长和角度选择特性,对器件设计中要考虑的问题进行了讨论。提出了实现多重体全息光栅波长解复用的实验方案和实用化要解决的问题。     

Raman-assisted femtosecond soliton switching and wavelength demultiplexing with optical fiber rocking filters

We analyze the femtosecond polarization and wavelength-dependent nonlinear switching response of birefringent fiber rocking filter. We show by perturbation theory and numerical simulations that, in the presence of the Raman self-frequency shift, the soliton switching efficiency may be optimized by injecting pulses in the fast fiber axis and with a negative wavelength offset from the center of the filter bandpass.     

Flat channel-passband-wavelength multiplexing and demultiplexing devices by multiple-Rowland-circle design

A new robust optical design for widening the channel passband of wavelength demultiplexers is presented. Instead of a traditional one-Rowland-circle design, a multi-Rowland-circle structure is proposed to tailor the focused image formed by the grating. The properties of channel passband can be controlled by adjusting the positions of the circles. Nearly perfect flat-channel passband was achieved by our simulation.     

Wavelength-locked, two-stage fibre Fabry-Perot filter for dense wavelength division demultiplexing in erbium-doped fibre amplifier spectrum

Insertion loss of 5.6 dB and finesse greater than 2000 within a 40 nm tuning range are demonstrated in a wavelength-locked, two-stage fibre Fabry-Perot filter capable of separating 1000 channels in an erbium-doped fibre amplifier spectrum.<>     

分散型多输入多输出雷达检测器设计及检测性能分析

对不同类型的目标,分散型多输入多输出(Multiple-Input Multiple-Output,MIMO)雷达的最佳检测器结构各异,且通常不便于工程实现.针对此问题,提出了一种易于工程实现的MIMO雷达检测器结构.首先对MIMO雷达和普通单基地雷达的回波信号模型进行分析,指出了MIMO雷达回波和单基地雷达快起伏目标多脉冲回波之间的相似关系.借鉴单基地雷达针对快起伏目标的检测器结构,提出分散型MIMO雷达可以采用类似的包络检波级联累加器的检测器结构形式.就所设计检测器结构对不同空域起伏目标的检测性能进行了研究,给出了检测性能的理论和仿真曲线.     

红外探测器滤光膜的研究与制备

为满足红外探测器在1.064 m和3~5 m双波段透射,在1.2~2.8 m波段反射,可适应复杂的环境条件、具有高稳定性和可靠性等要求,依据薄膜的设计理论,选择合理的膜系设计方法,借助TFC膜系设计软件对膜系结构进行优化设计。并采用电子束真空蒸发和离子辅助沉积技术,在蓝宝石晶体基底上镀制红外多波段滤光膜。同时对所使用的薄膜材料的光学、物理、化学和机械特性进行分析与研究。通过反复试验,优化工艺参数,使多波段滤光膜得以实现。对所制得的薄膜进行测试,基本满足红外探测器的使用要求。     

便携式超声探伤仪器的功能分析与设计

针对火车轮对超声探伤问题,提出一种便携式数字化超声探伤系统的设计方案,该方案采用高速数据采集,ADC的采样速率为15Msps,软件设计上有距离补偿、峰值搜索和包络检测等功能,对于便携式超声探伤仪的研制有借鉴意义。     

Micro air vehicle: configuration, analysis, fabrication, and test

This paper presents the development of two electrically powered micro air vehicle (MAV) prototypes with wingspans of 380 and 360 mm, respectively. A miniature flight control system is constructed using small and light components. A vision system consisting of a micro radio frequency (RF) transmitter and a miniature vision-receiving antenna with a low-noise amplifier is designed, which exhibits advantages over commercial ones. The aerodynamics of several airfoil sections at low chord Reynolds numbers are theoretically analyzed, for the layout of on-board components and the airfoil design. A small-sized propulsion/power testing setup is developed to measure and analyze the static performance of the motor/propeller/battery combination used for MAV prototype. The materials and methods used to build MAV prototypes are also presented. Two MAV prototypes, TH380 and TH360, have been successfully tested in the flight, where TH360 MAV with a payload of a home-made micro vision system can acquire the images of objects and transmit them back to the ground station.     

ARROW-type vertical coupler filter: design and fabrication

Vertical coupler filters (VCF) exhibiting narrow bandwidth and low sidelobe levels have been designed and demonstrated. Narrow bandwidth filter response is achieved due to the strong asymmetry between the waveguides of the filter and the nondispersive characteristics of the anitresonant reflecting optical waveguide (ARROW) structure. An ARROW-type VCF with a conventional parallel coupled directional coupler configuration with a full width at half-maximum (FWHM) of 1.36 nm and a maximum sidelobe level of -8.5 dB was fabricated using a compound glass consisting of SiO₂ and SiO₂-Ta₂O₅ . The filter sidelobe levels were then further suppressed by using an X-crossing arrangement to provide coupling strength apodization along the device. The sidelobe levels of this modified X-crossing filter were suppressed to below -23 dB and the measured FWHM was 3.9 nm. The central wavelength of the reported filters are in the 1.55 μm region. The measured results are in good agreement with theoretical results from an analysis procedure that combines the coupled mode theory with the finite difference complex mode solver     

Experimental demonstration of fast simultaneous wavelength switching and time demultiplexing using a nonlinear optical loop mirror

Simultaneous all-optical high-speed wavelength switching and time demultiplexing is experimentally demonstrated using a nonlinear optical loop mirror, an integrated passive wavelength router, and fast optical space switches. With >1.2-GHz wavelength switching speeds and 2.5 Gb/s time demultiplexing speeds, both packet switching and isolated-bit extraction are demonstrated. The time switching can potentially be applied to data rates >100 Gb/s.     

双光纤布拉格光栅波长锁定器的设计与制备

运用耦合模理论推导了双光纤布拉格光栅的透射率和反射率的解析表达式,利用相关表达式计算和分析了双光纤布拉格光栅的反射特性,并与单光纤布拉格光栅作了比较.讨论了双光纤布拉格光栅反射特性与光栅间距、光栅长度和折射率微扰最大值之间的关系,为双光纤布拉格光栅波长锁定器的设计与制备提供了理论依据.最终获得双光纤布拉格光栅的结构和特性参数,并与实测的数据进行比较,结果表明两者较为一致.     

片式无源温度补偿衰减器——原理、设计、制作、应用及发展趋势

无源温度补偿衰减器主要用于稳定射频微波放大器的增益随温度的变化。本文对该类器件的原理、设计、制作、应用及发展趋势等各方面做了系统的介绍。相对于其他补偿方案,使用此类器件具有设计简单、成本低、性能优异等特点。无源温补衰减器的核心设计在于选取正温度系数(PTC)和负温度系数(NTC)热敏电阻的阻值及其温度系数,以使衰减量随温度接近线性变化而保持特征阻抗基本不变。目前,此类器件主要采用厚膜工艺制作,其关键材料为系列化的热敏电阻浆料。薄膜化是器件未来发展的重要方向,而其中NTC热敏电阻的薄膜化仍面临重大的技术挑战,需要解决材料性能及其系列化等难题。     

The design of point detector arrays, I

This paper considers the design of a detection system to optimally detect known signal fields--scalar functions of a vector argument--corrupted by an additive noise field. The detection system has as its inputsnsamples (in Space) of the signal-plus-noise field; each spatial sample is the output of a point detector. Optimal processing of the point-detector outputs, as well as the locations of the point detectors, is considered. For a fixed array and under assumptions that are often physically reasonable, the optimum detector is separable into a spatial combiner and a temporal processor. The probability of error of the optimum detector is a monotonic function of the array gain. Convenient expressions of the array gain are found for circular arrays; by using these expressions, optimal radii for circular arrays are found.     

Bismuth oxide nonlinear fibre-based 80 Gbit/s wavelength conversion and demultiplexing using cross-phase modulation and filtering scheme

Reported is the experimental demonstration of wavelength conversion and subsequent demultiplexing of an 80 Gbit/s OTDM signal using the cross-phase modulation and spectral filtering technique in short lengths of bismuth oxide-based nonlinear fibre with a nonlinearity of /spl gamma/=/spl sim/1100 W/sup -1/ /spl middot/ km/sup -1/. Error-free, overall operation is readily achieved over a wavelength tuning range of /spl sim/10 nm.