High-bandwidth, high-numerical aperture graded-index polymeroptical fiber

A new large core (0.5-1.0 mm) graded-index polymer optical fiber was proposed to solve the connection problem of the single-mode silica fiber indoor use for high speed multimedia network. The bending loss for 10-mm bending diameter was dramatically decreased from 20 dB to less than 1 dB by preparing the high numerical aperture graded-index polymer optical fiber. The bandwidth was 585.2 MHz km which was one hundred times larger than that of any existent step-index polymer optical fibers, and the attenuation was 150 dB/km at 650-nm wavelength     

大模场宽频单模光子晶体光纤的设计与制备

文章对无尽单模光子晶体光纤进行了理论设计,并提出了微结构光纤的制造工艺技术和相应的光纤拉丝工艺参数,制造出了较大模场的宽频单模光子晶体光纤,该光纤的芯直径为13.1 μm,微孔直径为3.2 μm,孔间距为8.2 μm,1 550 nm波长的模场直径为14.6 μm,1 550 nm的衰减为0.6 dB/km,1 383 nm水峰为14.9 dB/km.截止波长测试和近场光强分布检验表明,该光子晶体光纤确实具备较宽的单模工作范围.     

Large-core, high-bandwidth polymer optical fiber for near infrareduse

High bandwidth (more than 500 MHz·km) graded-index polymer optical fiber (GI POF) for near infra-red use was successfully fabricated by using partially fluorinated acrylate polymer. Since only three carbon-hydrogen bonds exist in a monomer unit, an absorption loss due to the stretching vibration of the carbon-hydrogen bond was remarkably reduced compared with the conventional POF's. The attenuation of the GI POF at 780-nm wavelength was 135 dB/km, which is much lower than that of the PMMA core POF (800 dB/km). The fluorinated polymer-based GI POF is satisfying a significant segment of high-speed multimedia network applications     

An electric field tunable switch with liquid crystal infiltrated photonic crystal fiber grating

The nematic liquid crystal（NLC）infiltrated photonic crystal fiber（PCF）used as a switch modulated by electric field is demonstrated.The switch consists of the infiltrated solid core PCF into which Bragg gratings are written.It is confirmed that the switch can achieve an accurate operation through measuring the reflected light with the change of electric field intensity from 1.4 kVrms/mm to 2.1 kVrms/mm.When the electric field intensity exceeds the threshold,the change of only 0.01 kVrms/mm can cause the wavelength shift of 1 nm.It is approved that the switch with such a structure provides a high sensitivity.The reflection peak is stabilized at about 15 dB which is high enough to separate from the factors such as system noise and error,and it can improve the control precision.     

A high-speed low-voltage stress-induced micromachined 2×2optical switch

A low-voltage electrostatically actuated 2×2 fiber optic switch is achieved using a stress-induced curved polysilicon actuator. The curved polysilicon beam substantially lowers the electrostatic operating voltage of the switch. Large mirror displacement (300 μm) and low operating voltage (20 V) are obtained simultaneously. Sub-millisecond switching time (<600 μs), low optical insertion loss (0.7 dB), and small polarization-dependent loss (0.09 dB) have been achieved     

光子晶体光纤在全光网中的应用

光子晶体光纤(PCF)以其独特的光学特性和灵活设计的特点,而成为近年来研究的热点.随着各种新型PCF的问世以及研究的深入,使其应用领域不断扩大.文章对PCF在全光网中的各项应用进行了分析,重点对PCF在光纤光栅和光纤激光器、放大器、光开关、波长变换器方面的研究进展进行了介绍.     

High-Speed GaN-Based Green Light-Emitting Diodes With Partially n-Doped Active Layers and Current-Confined Apertures

We demonstrate a high-speed GaN-based green light-emitting diode for plastic optical fiber (POF) communication applications. By using a combination of n-type doping and undoped In_xGa_1-xN/GaN based multiple quantum wells (MQWs), and a 76-mum-diameter current-confined aperture structure, we can obtain an extremely high electrical-to-optical (E-O) 3 dB bandwidth (~330 MHz), which is limited by the spontaneous recombination lifetime of the MQWs. A reasonable coupled power (-264 muW) can be simultaneously achieved for a 2 mm in diameter POF with a 0.5 numerical aperture (NA).     

环烯烃共聚物空芯微结构太赫兹光纤的设计与制造

以环烯烃共聚物（cyclic-olefin copolymer,COC）材料为基质,设计、制造了一种空芯多孔包层太赫兹（THz）纤维。利用comsol 软件模拟了芯径为6 mm 的光纤在0.2~1.5 THz 波段的损耗特性,结果表明:在0.85~1.5 THz 波段存在多个低损耗频带,而且在0.85~1.1 THz 波段有低于3 dB/m 的三个窗口;特别是在0.99 THz,损耗达到0.208 dB/m。芯径为3 mm、4.8 mm 和6 mm 的光纤在0.8~1.5 THz 波段的损耗特性对比分析表明:该COC 微结构多孔包层空芯纤维的损耗随着光纤外径的增加而减小。把设计的太赫兹纤维外径放大7 倍达到7 cm,据此设计制造了光纤预制棒成型专用模具。借助热挤出成型方法得到了结构完整、孔洞表面光滑,长度为22 cm 的空芯多孔包层预制棒。利用该实验室独有的微结构光纤拉丝塔,成功获得了微结构保持完好的光纤样品。损耗分析结果表明:6 mm 芯径的光纤样品在1.27 THz 的平均损耗为2.175 dB/m,与该频率的理论损耗（1.95 dB/m）接近。     

Penalty-free dispersion-managed soliton transmission over a 100-km low-loss PCF

A long photonic-crystal fiber (PCF) with a low loss was successfully fabricated by first preparing a large pure silica glass preform. The fiber is 100 km long and has a low loss of 0.3 dB/km at 1550 nm. The fiber has a Rayleigh scattering coefficient of 0.85 dB/(km/spl middot//spl mu/m/sup 4/), which is the lowest value ever reported in a PCF. Using this fiber, the first penalty-free dispersion-managed soliton transmission at 10 Gb/s was achieved in a PCF.     

Ultrahigh Birefringent Photonic Crystal Fiber With Ultralow Confinement Loss

A photonic crystal fiber (PCF) with circular air holes in the fiber cladding and elliptical air holes in the fiber core is proposed. According to calculation, both ultrahigh birefringence (larger than 0.01) and ultralow confinement loss (less than 0.001dB/km) can be achieved simultaneously over a large wavelength range for a PCF with only four rings of circular air holes in the fiber cladding. The confinement loss in this PCF can be effectively reduced while the birefringence almost remains the same. The proposed design of the PCF is a solution to the tradeoff between the birefringence and the confinement loss for the originally reported highly birefringent elliptical-hole PCF. Moreover, an approach to modify the effective index of fiber core is also suggested in this letter     

塑料光纤性能测试及应用

介绍了塑料光纤在高速度、短距离网络中的优势,并设计实验对PMMA塑料光纤的光谱损耗以及丢包率进行测试,被测塑料光纤在650 nm工作波长的损耗系数为143 dB/km,且在100 Mb/s传输速度下,传输60 m无丢包现象,表明塑料光纤作为传输介质完全可以满足局域网的传输要求.在此结论基础上,提出网络解决方案,将塑料光...     

基于聚合物光纤局域网系统的自由空间光通信

设计了与125 Mbps聚合物光纤局域网兼容的自由空间光通信系统,以实现楼宇间的数据通信,克服聚合物光纤传输距离较短的缺点.自由空间光通信包括发射和接收两个部分,发射部分由650 nm半导体激光器,驱动电路和准直扩束镜组成,接收部分由接收透镜和光电探测器组成.半导体激光器的调制发射功率为3 dBm,光电探测器的探测灵敏度为-27 dBm.分析了大气对光信号的衰减以及大气湍流造成的光斑抖动对通信的影响,记录了系统的信号传输波形和通信眼图.实验表明,自由空间光通信可以延长聚合物光纤局域网的通信距离,使其在实际工程中的应用更加灵活.     

大容量中心束管式光纤带光缆的设计与制造

随着通信行业向着数字化、宽带化、智能化方向的发展,光纤网络的建设将由骨干网转向局域网与城域网,由于连接的节点较多,往往需要铺设大芯数的光纤光缆。中心束管式光纤带光缆因其集成度高、占用路由资源少、成本低等特点,将会得到广泛应用。本文就大容量中心束管式光纤带光缆的设计与制造进行探讨。     

Impulse response analysis of graded index polymer optical fiber

Polymer optical fibers (POF) are of great interest the last decade in optical communication networks for short and medium distance applications. Based on the theory of generalized impulse response of multimode channels, an analytical method for time response evaluation is proposed for a graded index polymer optical fiber (GIPOF) with polymethylmeta-crylate (PMMA) core material.     

低损耗光子晶体光纤的研究进展

损耗是传统光纤和光子晶体光纤得以实用化的重要参量之一,降低损耗是光子晶体光纤制备的首要问题.折射率引导型光子晶体光纤的损耗由1999年的240 dB/km降至0.28 dB/km(1550 nm波长处),光子带隙型光子晶体光纤的损耗也降低到1.2 dB/km(1620 nm波长处).在对比传统石英光纤损耗来源基础上,阐述了光子晶体光纤的损耗机理,并说明了损耗降低的主要途径.     

选择性填充光子晶体光纤应变特性研究

微结构的光子晶体光纤,通过填充光敏等功能材料,具有可调谐、全光纤结构和易于集成等优点,是光纤光子器件发展的重要方向.毛细管法将高折射率的匹配液,填充到空心光子晶体光纤中邻近纤芯的空气孔中,两端熔接单模光纤,制成高灵敏的应变传感器.实验表明,当填充30mm长,折射率为1.508的匹配液时,测得应变灵敏度约为每应变4.36pm.实验结果与仿真结果相符,这种装置可用于高灵敏的应变传感.     

Optical fiber up-tapers with high beam expansion ratios forcomponent fabrication

Optical fibre up-tapers with beam expansion ratios of 10, about twice the previously achieved value for the same taper outer diameter, have been fabricated and characterized. The increased beam expansion is achieved with a near step-index profile for the core of the taper. The excess coupling loss between two tapers is less than 0.1 dB. A lateral offset of more than 20 μm or an axial displacement of 4 mm between tapers caused an excess loss of 1 dB. The angular tolerance for this loss is a manageable 0.3°. These tapers permit, for a given beam expansion ratio, the manufacture of smaller outer diameter, more compact structures of self-aligned beam expansion. They also permit the insertion of optical elements into the expanded beam for the fabrication of inline single-mode passive fiber components     

基于非对称双芯光子晶体光纤的宽带定向耦合器研究

A novel broadband directional coupler based on an asymmetric dual-core photonic crystal fibet(PCF)is proposed.The asymmetry in the fiher is introduced by the enlargement of one air-hole in dual-core PCF.Numerical investigation demonstrate that broadband directional coupling with spectral width as large as 370 nm and polarization-dependent loss and uniformity lower than 0.2 and 0.5 dB,respectively,can be achieved.In addition,the proposed fiber shows large tolerance to the variation of the fiber parameters.In particular,the fiber length allows at least 10%derivation from the proposed fiber length of 7.7 mm.     

Design of Wideband Single-Polarization Single-Mode Photonic Crystal Fiber

The present paper proposes a novel design for achieving single-polarization single-mode (SPSM) operation in photonic crystal fiber (PCF), using a rectangular-lattice PCF with two lines of three central air holes enlarged. The proposed PCF that is composed entirely of silica material is modeled by a full-vector finite element method with anisotropic perfectly matched layers. The position of the region of single polarization can be tuned freely by adjusting the size of the central enlarged air holes. Using this structure, an SPSM PCF with confinement loss less than 0.1 dB/km within the wavelength range from 1.20 to 1.66 mum and effective mode area about 5.9 mum² at 1.55 mum has been successfully designed. The proposed fiber is a nonlinear SPSM, which may be useful for nonlinear optical applications or applications with a wide SPSM operating bandwidth requirement     

Analysis and Simulation of a Plastic Optical Fiber Access Network Based on OCDMA Technology

In this paper a plastic optical fiber (POF) access network based on optical code-division multiple access (OCDMA) technology is proposed. Recently, optical transmission using POF has received much attention due to its low weight, large core diameter, flexibility, and easy installation. Specially, its high bandwidth makes POF a very attractive candidate for a transmission media in an access network based on OCDMA technology. A conventional OCDMA system only allows a finite number of units to transmit and access simultaneously according to the number of channels which is restricted by BER. To resolve this problem a novel protocol is also proposed in this paper. The protocol can efficiently support variable-sized messages, and any new unit can join the network at any time without requiring network initialization. To implement the demonstration, each optical network unit is equipped with a fixed and a tunable optical encoder/decoder. The optical encoder/decoder employing planar holographic optical processors (HOPs) in this system may be of low fabrication cost. The network throughput and average delay using various system parameters has been investigated by numerical analysis and simulation experiments. It is shown that the dynamic control protocol in this POF access network based on OCDMA technology is valid and efficient.