Integrated optical fiber data link transmitter/receiver for local area network application

Optical fiber data link transmitters and receivers have been developed for local area network applications. The features are of wide-bit-rate range and wide dynamic range as well as compact and of highly reliable construction. State-of-the-art LSI technology has been applied for the circuit electronics integration. Design emphasis was also placed on the optical connector development for ease of operation as well as reliable connection and compact size.

The data link transmitter and receiver developed utilize an AlGaAs light-emitting diode and a Si PIN photodiode as the light source and detector, respectively. Performance data were obtained for a bit rate range of dc to 35 Mbps and an 18–dB dynamic range.     

High-Performance Fiber-Optic Link for Electronic Countermeasure Antenna Remoting

The ability to remotely radiate microwave signals has become an essential feature of modern electronic countermeasure (ECM) systems. The use of fiber optics allows remote microwave links to be constructed that have very low propagation loss and dispersion, are very flexible and light in weight, and have a high degree of immunity from external electromagnetic fields, cross talk, and environmental effects. This combination of desirable characteristics is beneficial to avionic ECM antenna remoting as well as many other applications. GEC-Marconi has developed high-per formance fiber components for use in a towed radar decoy. The resulting rugged and compact optical transmitter and receiver modules have been proven to maintain the required performance over the full hostile range of environmental conditions en countered on a fast jet. Packaged fiber-optic links have been produced that can achieve a compression dynamic range of 87 dB in a 1-MHz bandwidth over a 2- to 18-GHz range.     

Optimization of an Externally Modulated RF Photonic Link

The noise figure and sub-octave spurious-free dynamic range of a carrier-suppressed analog RF photonic link are examined. Expressions for noise figure and dynamic range are derived as a function of the modulator bias angle. A closed form expression for the bias angle that optimizes link noise figure and spurious-free dynamic range is also derived. Experimental results are presented and shown to agree with calculations. These experimental results include some of the lowest noise figure and highest dynamic range results published to date for an RF photonic link incorporating a standard Mach-Zehnder modulator: 6 dB and 122 dB·Hz^2/3, respectively.     

Linearized analog photonic links based on a dual-parallel polarization modulator

A linearized analog photonic link (APL) is proposed based on an integratable electro-optic dual-parallel polarization modulator (DPPolM), which consists of two polarization beam splitters and two polarization modulators (PolMs). Theoretical analysis shows that the APL is potentially free from the third-order nonlinear distortion if a polarization controller placed before the DPPolM is carefully adjusted. A proof-of-concept experiment is carried out. A reduction of the third-order intermodulation components as high as 40 dB and an improvement of the spurious-free dynamic range as large as 15.5 dB is achieved as compared with a single PolM-based link. The DPPolM-based APL is simple, compact, and power efficient since it requires only one laser, one modulator, and one photodetector.     

Optimization of an Externally Modulated RF Photonic Link

Abstract

The noise figure and sub-octave spurious-free dynamic range of a carrier-suppressed analog RF photonic link are examined. Expressions for noise figure and dynamic range are derived as a function of the modulator bias angle. A closed form expression for the bias angle that optimizes link noise figure and spurious-free dynamic range is also derived. Experimental results are presented and shown to agree with calculations. These experimental results include some of the lowest noise figure and highest dynamic range results published to date for an RF photonic link incorporating a standard Mach-Zehnder modulator: 6 dB and 122 dB·Hz^2/3, respectively.     

Fluorescence lifetime-based biosensing of zinc: Origin of the broad dynamic range

Fluorescence lifetime-based chemical sensors have recently been described for applications in medicine, environmental monitoring, and bioprocess control. These sensors transduce the level of the analyte as a change in the apparent fluorescence lifetime of an indicator phase. We have previously developed a wavelength-ratiometric fluorescence biosensor for zinc based on binding of zinc and dansylamide to apo-carbonic anhydrase which exhibited high sensitivity and selectivity. We demonstrate that the apo-carbonic anhydrase/dansylamide indicator system is very well suited for lifetime-based sensing, with a subnanomolar detection limit and greater than 1000-fold dynamic range. The theoretical basis for the wide dynamic range is discussed.     

Adaptive control of laser modal properties

An adaptive optical system for precise control of a laser beam's mode structure has been developed. The system uses a dynamic lens based on controlled optical path deformation in a dichroic optical element that is heated with an auxiliary laser. Our method is essentially aberration free, has high dynamic range, and can be implemented with high average power laser beams where other adaptive optics methods fail. A quantitative model agrees well with our experimental data and demonstrates the potential of our method as a mode-matching and beam-shaping element for future large-scale gravitational wave detectors.     

Airborne laser radar for mapping two-dimensional contours of aerosol concentration

An improved version of a compact dye laser radar system with real-time data analysis capability has been developed for aircraft installation. The system is designed for use in mapping two-dimensional contours of aerosol backscattering coefficients both above and below the aircraft. The laser radar is part of a larger system which has been developed to characterize the optical properties of aerosols as well as their spatial and temporal variability.     

高速双光谱遥感图像传输系统

提出并设计了一种高速舣光谱遥感图像传输系统.对该系统所采用的传输策略,传输帧结构以及时序恢复等问题进行了深入的研究.首先,将双探测器一行数据中有效部分提取后传输,采用行有效标志中断发送的方式在接收端恢复时序,保证了系统输入输出数据、时序的完全一致;接着,采用发送与接收缓存机制,利用时分复用打法将双探测器的数据在单根光纤...     

Second-harmonic generation frequency-resolved optical gating analysis of low-intensity shaped femtosecond pulses at 1.55 mum

We illustrate observation and characterization of medium- and low-intensity shaped ultrashort pulses at lambda=1.55mum through single-shot geometry (multishot-average) second-harmonic generation-frequency-resolved optical gating. The pulses are shaped by amplitude filters in the Fourier plane of a compact folded shaper. Sensitivity to pulses with energies of less than 20 pJ and high dynamic range is reported for this configuration. Application of this method to the propagation of ~170-fs pulses through a 50-m fiber link is also illustrated.     

Tunable ultraviolet optical parametric oscillator for differential absorption lidar measurements of tropospheric ozone

A pulsed optical parametric oscillator (OPO) with intracavity sum frequency mixing was developed generating energies of up to 16 mJ in the 281–293 nm wavelength range. Both OPO process and sum frequency mixing are pumped by the harmonics of a single, medium-sized Nd:YAG laser. The system is characterized by a high overall efficiency (∼4% conversion from 1064 nm to the UV), a very compact set-up and stable and reliable operation. This system was successfully employed to measure tropospheric ozone using the differential absorption lidar (DIAL) technique and shows much promise as a lidar transmitter in airborne case studies as well as in unattended lidar systems for long-term monitoring. An unattended ozone profiling system could already be successfully realized. Received: 1 April 2002 / Revised version: 30 May 2002 / Published online: 2 September 2002 RID="*" ID="*"Corresponding author. Fax: +49-8153/28-1271, E-mail: Andreas.Fix@dlr.de     

一种远程HPM测量数据采集系统的设计与实现

为获取某型高功率微波辐射系统辐射至空中靶目标处(数十m至数百km处)的微波脉冲参数,基于某升空平台无线数传链路,设计了一种结构简单、紧凑的远程无线高功率微波辐射场测量数据采集系统。该系统具备运行状态动态指示、测量参数远程设置以及波形数据实时显示等功能,质量小于2 kg,瞬时动态范围大于15 dB。试验结果表明:测量系统具备高重频微波脉冲参数测量能力,能实时有效捕获辐射场微波波形,运行稳定可靠,可满足百km级距离上的空中辐射场测量需求。     

强流电子束二极管陶瓷真空界面

从绝缘和机械强度两方面优化设计了一种应用于强流电子束二极管的陶瓷真空界面。首先,依据真空沿面闪络机理及其影响因素,针对外径220mm的陶瓷板,应用ANSYS静电场模拟,通过对阴极电极形状和阳极外壳尺寸的调整,使得陶瓷沿面电场和阴、阳极三结合点场强均得到了有效控制。模拟结果显示:陶瓷沿面电场分布均匀,阴、阳极三结合点场强小于30kV/cm,电场线与陶瓷表面所成角度基本保持在45°;其次,针对陶瓷与电极的约束结构,通过静力和瞬态冲击分析,确定了该陶瓷界面可承受的最大静压和冲击波最大峰压分别为4.8MPa和60MPa;最后,在脉宽200ns的脉冲功率驱动源上进行了实验研究,陶瓷真空界面平均绝缘场强达到44kV/cm,二极管运行稳定,机械性能可靠,实验结果与理论设计相符。     

Optical performance models for FDDI links

A loss budget model has been developed to predict optical perjormnce of the fiber distributed-data interjace (FDDI) type of networks in the premises-distribution environment. This model tailors existing statistical loss budget models to the FDDI standard. It is expected that as FDDI becomes popular, fiber-based distribution systems will become common. When designing a fiber-distribution system, it is important to understand the constraints placed on link perjormance by the cable plant. To determine these constraints, the model is examined numerically using a large range of initial conditions. The total link length is used as the dependent variable. This set of initial conditions corresponds to an ensemble ofpossible link configurations, and these link configurations are studied in the context of the premises-distribution environment.

The model is extended to include the use of optical bypass switches. Laboratory measurement data are presented to verify the accuracy of the bypass switch model. The extended model, including the bypass switch, is examined numerically for a similar set of initial conditions. These constraints are applied to the use of bypass switches in wiring closets, between Jlaors, and at the work location. Distance limitations are determined for FDDI links utilizing optical bypass switches.     

像元间距为25μm、160×120元无热电制冷器的非致冷非晶硅探测器（英文）

介绍用非晶硅微型辐射热量计制成的160×120元非致冷红外焦平面阵列的特点和性能，该阵列集成在一个无铅芯片载体封装中，像素间距为25μm，适合于大批量生产。 25μm像元结构得益于较小的热时间常数，该技术使我们能够设计出更高的热隔离性能，从而能以35μm技术为基础开发出25μm技术。通过采用新的像素设计和更进一步推动设计方法，在没有采用复杂昂贵的双层结构的前提下，保持了较高填充因子。从读出集成电路结构、封装、可操作性和光电性能入手对该探测器进行了介绍。为该探测器设计了一种新型集成读出电路。可以通过串行链接对增益、图像翻转和积分时间等高级功能进行操控，降低电气对接的数量。研制的小型无铅芯片载体封装便于大规模生产探测器，主要用途为便携式摄像机或头盔摄像机。     

基于双平行马赫-曾德尔调制器的大动态范围微波光子下变频方法

为了提高微波光子下变频链路的性能,提出了基于集成双平行马赫-曾德尔调制器的微波光子下变频方法.通过理论推导和数值仿真分析了系统的增益和无杂散动态范围,实验搭建了基于双平行马赫-曾德尔调制器的下变频链路,控制直流偏置电压使双平行马赫-曾德尔调制器工作在高载波抑制的双边带调制模式,并对链路进行了性能测试.实验结果表明:该下变频链路的增益为7.43 d B,无杂散动态范围达到了110.85 d B/Hz2/3,工作频段可覆盖5—18 GHz的宽频范围.基于双平行马赫-曾德尔调制器的下变频方法可优化设计输出频谱,系统结构简单、易于实现,为微波光子下变频链路提供了有效的解决方案.     

MONTE CARLO STUDIES OF RADIATION DAMAGE INDUCED BY FUSION DYNAMIC SIMULATION OF SPUTTERING

In this paper, the sputtering caused by fusion of ⁴He particles in the first wall materials is investigated by using the dynamic Monte Carlo simulation, which is based on the binary collision approximation. The dependences of sputtering yields on the incident energy and angle, as well as the comparisons of results calculated using the Monte Carlo methed with results from experiments, are discussed. Energy spectrum and angular distributions of sputtered species, the depth of origin of the sputtered particles as well as range distributions of incident ions are given. From a comparison between the related experimental data and the calculated results with static and dynamic simulation it has been found that a better agreement is obtained for dynamic simulation.     

On the dynamics and control of a polymer film compact heat exchanger

Process intensification has the potential to change the state of the chemical and process industries. The polymer film compact heat exchanger (PFCHE) is a new type of intensified heat exchanger. The potential market is seen as being large [1] but as yet the unit has not been adopted by industry. The advantageous heat transfer characteristics of such a unit have been shown in previous work [2]. This work investigates the dynamic behaviour of the PFCHE and the process control problems that may arise.The PFCHE available at Newcastle University has been used to generate dynamic temperature data. The data have been employed to formulate and validate time series type models. These models were then used in simulated process control studies. The dynamic behaviour of the unit appeared to be linear and response times were quick. It was found that the responses of the model to disturbances in inlet temperatures could be controlled well using a digital form of PI control. There were, however, doubts as to the ability of the model to completely replicate the system.     

Interchip link system using an optical wiring method

A chip-scale optical link system is presented with a transmitter/receiver and optical wire link. The interchip link system consists of a metal optical bench, a printed circuit board module, a driver/receiver integrated circuit, a vertical cavity surface-emitting laser/photodiode array, and an optical wire link composed of plastic optical fibers (POFs). We have developed a downsized POF and an optical wiring method that allows on-site installation with a simple annealing as optical wiring technologies for achieving high-density optical interchip interconnection within such devices. Successful data transfer measurements are presented.     

Effective and simplified hybrid TEA laser design and operation

A compact hybrid TEA CO₂ laser has been developed which, when operated with the low pressure section well below oscillation threshold, demonstrates that little cw gain is necessary to ensure single longitudinal mode (SLM) output pulses with peak power, energy and pulse shape approaching those of normal multi-mode operation. This has allowed reliable SLM operation to be obtained with a very short, wide bore rf-excited low-pressure section, making feasible simple single-mode, large-aperture TEA lasers with high peak powers and energies.