光纤通信用光源亮点凸现

(上接12期) WDM用光源 用于WDM系统的波长可控光源、波长可调光源和多波长光源是目前研究的重点。对应用于WDM系统光源的要求是发光波长必须精确、稳定、可靠性高、成本低、便于集成、并有与之配套的波长监测与稳定技术。目前,已开发了多波长光源、绝对波长光源、分布反馈型激光器和超级周期结构衍射光栅分布反馈型激光器等波长可调半导体激光器以及多波长光纤环形激光器等。     

可控照明有助于精确的紫外固化

Moritex欧洲公司现已开发出一种程控反馈紫外光源。这种新型程控反馈紫外光源具有通用的功率输入的特点。采用专利光学反馈控制技术使石英卤素灯的紫外辐照极其稳定。利用独特光源的反馈输入可以精确地控制紫外辐照的功率水平。紫外光的强度可以通过程控达到恒定的水平、阶跃式增长或实现间歇式脉冲辐照。这种程控光源适于优化紫外固化,亦可应用于等离子体/液晶显示器密封、光纤/套筒接合以及透镜和棱镜的连接。Moritex石英卤素灯在较高的色温(>3000K)下输出稳定。与白炽灯相比,其使用寿命长(500～2000h)。光源设计所要求的安全性和可靠性…     

可控照明有助于精确的紫外固化

Moritex欧洲公司现已开发出一种程控反馈紫外光源。这种新型程控反馈紫外光源具有通用的功率输入的特点。采用专利光学反馈控制技术使石英卤素灯的紫外辐照极其稳定。利用独特光源的反馈输入可以精确地控制紫外辐照的功率水平。紫外光的强度可以通过程控达到恒定的水平、阶跃式增长或实现间歇式脉冲辐照。这种程控光源适于优化紫外固化,亦可应用于等离子体/液晶显示器密封、光纤/套筒接合以及透镜和棱镜的连接。Moritex石英卤素灯在较高的色温(>3000K)下输出稳定。与白炽灯相比,其使用寿命长(500～2000h)。光源设计所要求的安全性和可靠性…     

双发光二极管

据休斯飞机公司报导一种获得高可靠性的双发光二极管,这种双发光二极管同时封装在一个管壳内以获得极高的可靠性。把二个GaAs LED封装成一个单独的组件,其可靠性要比普通的单管封装结构高得多,其中一个作主光源,如果它失效了,可用另一个备用的二极管接通,两个二极管都有一个单独的电源引线,因此两个二极管能同时接通(或断开)或断开(或接通)其中一个。     

利用微区空间分辨漫反射测量组织光学特性

为了准确测量光源附近微区内的漫反射光分布,设计了一维光纤阵列探头,通过两个光开关的通道切换实现了对距离光源0.125～1.250 mm径向范围内10个位置漫反射光强的测量,空间分辨率为0.125 mm.实验测量的漫反射光分布与Monte Carlo(MC)结果相符合,验证了测量系统的可靠性,采用逆MC算法,实现了对生物组织模拟液光学参量的测量,测量结果与文献报道符合较好.     

模糊决策在接收光源信号分析中的应用

对于光学传感器接收光源信号中优先级确定的应用进行了详细介绍。由于模糊评判的应用，提高了区分光源信号的准确性，从而也提高了整个系统工作的可靠性。     

用于单模光纤通信线路中的高可靠性半导体激光器的设计与制造

长途干线远程通信系统,特别是海底光缆系统尤其需要可靠性。本文描述了通过最低限度地减小众所周知的退化损伤而被用作这种单模系统光源的InGaAsP倒置肋波导(IRW)激光器是怎样设计的。本文归纳了大量可靠性保证程序的结果,在七百万小时寿命试验之后得到的结论证实IRW激光器的可靠性性能非常良好。现在这种器件正广泛地用于陆地通信线路系统,并首先用于英国与比利时之间的海底光缆系统。     

科锐新款LED亮度、光色品质和一致性提高到新的水平将全面替代卤素灯

科锐公司(CREE)日前宣布将LED的亮度、光色品质和一致性提高到了新的水平,向全面替代高能耗卤素光源的目标又迈出了新的一步。新款XLamp MT-GLED具备更高的亮度、无与伦比的光色品质和久经考验的照明级可靠性。新款MT-GLED的亮度比原来提     

照相手机内置闪光灯需求激增白光LED后势看涨

闪光灯是一个用途非常广泛的辅助摄像光源,当拍摄时周围环境的自然光源(日光)或人工光源(灯光)等不足的时候,闪光灯就成了弥补这一不足的机动光源,闪光灯与其它光源最大不同点是闪光灯为瞬间明灭的光源,发光时间短促而光度强烈.     

波分复用ROF系统中光发射源的频率稳定度研究

研究了波分复用微波光子(ROF)系统中超连续谱光源的产生及其特性.利用电吸收(EA)外调制10GHz分布反馈式(DFB)激光器产生的超短光脉冲经过高非线性光纤(HNLF),通过数值模拟产生了多波长连续光源.对影响光源频率稳定度的因素进行了分析,数值模拟说明泵浦脉冲为无啁啾超短光脉冲时,生成的多波长光源为高相干性、低相对强度噪声(RIN)的可靠光源;RIN随HNLF光纤长度的增加而变差.     

发光二极管光源疗法在生物医学中的应用

综述了国内外以发光二极管为光源的光疗法在生物医学中的应用研究,主要从动物体试验,动物细胞实验和医学临床进行了分析,对医学临床进行了重点的分析研究。并从安全性、经济性、使用性等多方面比较分析了发光二极管光源疗法与其它光源疗法的优缺点。发光二极管光源疗法将在生物医学领域有广阔的应用,在产品商业化上也会有较大的发展。     

Light wave coupled flat panel displays and solid-state lighting using hybrid inorganic/organic materials

We present a review of light-emitting materials and devices that combine inorganic and organic lumophores and hosts. The essence of this hybrid inorganic/organic (I/O) approach is to combine materials, structures and devices from each category in such a way as to obtain best-of-both-worlds performance. The combination of high power/high efficiency inorganic light pump sources with high conversion efficiency organic lumophores is discussed in detail. In this type of Hybrid I/O device, near-ultraviolet (UV) or blue pump light is selectively converted to various visible colors based on the molecular structure of each lumophore. Since the lumophores are optically pumped their reliability is greatly increased compared to electrically pumped organic emitters. Methods for coupling the light from pumps to lumophores include direct path excitation (DPE) and light wave coupling (LWC). DPE uses one pump per lumophore pixel, which allows for active matrix style addressing, but requires large arrays of pumps. LWC uses either a single source or a small number of pump sources. To obtain pixelation for Hybrid I/O LWC devices we have developed a novel electrowetting switching method. Examples of Hybrid I/O displays and solid-state lighting are discussed.     

对大功率LED车灯芯片结温部分关键影响因素的研究

针对LED车灯芯片照明过程中结温过高的问题,文中对影响芯片结温高低的两种关键因素:LED车灯芯片内部发光源间距和芯片排布间距进行研究,以求有效降低芯片结温。通过ANSYS Workbench16.0软件进行芯片热仿真模拟,随后利用恒温测试平台对仿真结果可靠性进行了验证。验证结果表明,合理设置LED车灯芯片内部发光源之间的间距能有效降低芯片结温,最高可降低8.249 ℃;同时,适当增加LED车灯芯片之间排布间距亦可有效降低结温0.5 ℃。     

A polymer based miniature loop heat pipe with silicon substrate and temperature sensors for high brightness light-emitting diodes

Solid State Lighting (SSL) systems, powered by light-emitting diodes (LEDs), are revolutionizing the lighting industry with energy saving and enhanced performance compared to traditional light sources. However, around 70%–80% of the electric power will still be transferred to heat. As the elevated temperature negatively affects the maximum luminous output, efficiency, light quality, reliability and the lifetime of the SSL systems, thermal management is a key design aspect for LED products. In this work, an innovative thermal management with a package, a silicon substrate with temperature sensors and a polymer based loop heat pipe (LHP) was designed, manufactured and assembled. It can supply a low and relatively stable temperature to maintain higher optical power, more luminous flux and less color shift. In a word, the novel design can provide LEDs with the efficient thermal management and temperature monitoring with reduced weight, easy fabrication, less energy consumption and better light quality.     

Temperature‐controlled light‐emitting diode lamp for photovoltaic rural applications

In recent years, interest in light‐emitting diode (LED) lighting has been growing because of its high efficacy, lifetime and ruggedness. This paper proposes a better adaptation of LED lamps to the technical requirements of photovoltaic lighting domestic systems, whose main quality criteria are reliability and that behave as voltage power supplies. As the key element of reliability in LED lamps is temperature, a solution is proposed for driving LED lamps using voltage sources, such as photovoltaic system batteries, with a control architecture based on pulse width modulation signal that regulates the current applied according to the LED lamp temperature. A prototype of the LED lamp has been implemented and tested to show its good performance at different temperatures and at different battery voltages. Copyright © 2011 John Wiley & Sons, Ltd.     

Generation of ultra-wide and flat optical frequency comb based on electro-absorption modulator and frequency modulator

An ultra-wide and flat optical frequency comb (OFC) generation scheme using multiple continuous wave (CW) light sources based on electro-absorption modulator (EAM) and frequency modulator (FM) is proposed. In the scheme, each CW light source is broadened and modulated by the first EAM and FM, respectively. The second EAM is introduced to flatten the ultra-wide OFC lines. By setting the wavelength spacing of light sources equal to the bandwidth of sub-OFC, an ultra-wide OFC can be obtained. Principle analysis and simulation for the scheme are performed. The results show that in the case of a single light source, a tunable and flat OFC is obtained. With the increase of light sources, the bandwidth of the generated ultra-wide OFC expands rapidly. In the case of 28 light sources, a 22 GHz ultra-wide OFC with bandwidth of 16.52 THz can be generated.     

Design Rules for Addressing Material Asymmetry Induced by Templated Epitaxy for Integrated Heteroepitaxial On-Chip Light Sources

Integrating quantum dot (QD) gain elements onto Si photonic platforms via direct epitaxial growth is the ultimate solution for realizing on-chip light sources. Tremendous improvements in device performance and reliability have been demonstrated in devices grown on planar Si substrates in the last few years. Recently, electrically pumped QD lasers deposited in narrow oxide pockets in a butt-coupled configuration and on-chip coupling have been realized on patterned Si photonic wafers. However, the device yield and reliability, which ultimately determines the scalability of such technology, are limited by material uniformity. Here, detailed analysis is performed, both experimentally and theoretically, on the material asymmetry induced by the pocket geometry and provides unambiguous evidence suggesting that all pockets should be aligned to the [1 $\overline{1}0$] direction of the III-V crystal for high yield, high performance, and scalable on-chip light sources at 300 mm scale.     

可见光MIMO通信系统中级联编码的应用

可见光多输入多输出（MIMO）通信中空时分组编码能够获得较高的分集增益，但是其有效性较差，空间调制编码能够提高系统的频谱利用率但其可靠性较差。因此结合空时分组编码和空间调制编码的优势设计出空时分组-空间调制（STBC-SM）级联编码应用到可见光MIMO通信系统中，根据朗伯光源衰减特性建立了可见光室内传输信道模型，并对系统有效性及可靠性进行了仿真验证。结果表明在确保原有效性和相同误码率前提下，STBC-SM级联编码的可靠性较SM提高了5~8 dB，在确保原可靠性的前提下，STBC-SM级联编码的有效性较STBC提高了。表明文中设计的级联编码可有效的解决通信系统中有效性与可靠性的矛盾问题，为研究室内可见光MIMO通信提供了很好的理论意义。     

Thermal challenges deriving from the advances of display technologies

After a brief overview on development history of solid-state light sources, an light emitting diodes (LED)-backlit liquid crystal display television (LCD-TV) and a diffractive micro-electro-mechanical-system (MEMS) (GxL) laser projector are characterized for key performance indicators for their light sources, with highlight on thermal noise caused by Brownian motion of GxL ribbons. Then, we will propose a solution for thermal challenges in such a flat panel display using light sources with moderate power dissipation density, followed by discussion on necessity of advanced thermal spreader in cooling lasers with extremely high power dissipation density.     

Performance of an incoherent temporal-spreading OCDMA system with broadband light sources

The effect of the coherence time of light sources on the performance of an incoherent temporal-spreading optical-code-division multiple-access (OCDMA) system is studied in this paper. Broadband noise-like light sources, such as amplified spontaneous emission (ASE) sources, are used by the transmitters. Three different kinds of receiver structures are examined and compared. Results show the impact of the nonideal light sources on the system performances relative to the ideal case. Analysis shows that to achieve the best performance when the available optical bandwidth and data rate are fixed, there is an optimal range for the spreading code length.