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     

Near hexagonal close-packed optical fiber array for parallel optical interconnection

In conventional optical fiber based two-dimensional (2-D) parallel optical interconnection (POI), optical fiber arrays are aligned to 2-D light sources and detectors using precisely fabricated hole-plate or stacked V-groove plates. All these structures have problems in making positioning components and assembly with high accuracy. For polymer optical fibers with large diameter, the whole dimension of the array will be too large if they are positioned using V-grooves or hole-plate. This paper proposes a 2-D near hexagonal close-packed (NHCP) optical fiber array for 2-D POI. NHCP array has a cross-sectional profile of near-hexagonal lattice and with fibers precisely positioned at each node of lattice. Compared with perfect HCP lattice, NHCP lattice is slightly stretched in one dimension and still have all fibers with nonuniform diameter packed tightly with high packing fraction. The position of fibers in NHCP array is very important when aligned to 2-D light sources and detectors. This paper deduce the analytically expression for the probability distribution of fiber position which is related to variance of fiber diameter and structure parameters of NHCP array, and verified it by computer simulation. Experiment samples of NHCP array have been made showing that NHCP array is easy to be fabricated.     

Design and characteristics of large displacement optical fiber switch

Plastic optical fiber (POF) is suitable for indoor local area network (LAN), for example, in-home or office networks, because of its flexibility and its ease of connection due to its relatively large core diameter. A 1/spl times/2 optical switch for indoor LAN using POF and a shape memory alloy (SMA) coil actuator with magnetic latches was successfully fabricated and tested. In this paper, the design concept and the characteristics of this switch are described. To achieve switching by the movement of a POF, large displacement is necessary because the core diameter is large (e.g., 0.486 mm). A SMA coil actuator is used for large displacement and a magnetic latching system is employed for fixing the position of the shifted POF. For this design, the insertion loss is 0.40 to 0.50 dB and crosstalk is more than -50 dB without index-matching oil. Switching speed is less than 0.5 s at a driving current of 80 mA. A cycling test was performed 1.4 million times at room temperature. Another optical fiber switch was fabricated and successfully actuated using plastic clad fiber (PCF). PCF also has a large core diameter (e.g., 0.20 mm) and optical switches using PCF will be useful for short distance networks between buildings.     

Optical Fiber System Applications Aspects in Future NTT Networks

This paper describes some aspects of optical fiber cable system applications in future NTT transmission networks, considering voice transmission as predominant even in future transmission networks in accordance with demand forecasts. The desirable optical fiber cable transmission system which should be developed and introduced is discussed taking into account optical fiber costs, demand estimates, pertinent technological developments, etc. It was concluded that the following process of introducing optical fiber cable transmission systems should be feasible. In the first step, approximately 32 Mbit/s and 100 Mbit/s digital transmission systems should be employed for short and medium haul trunks with heavy traffic using graded index optical fibers. A large capacity, long haul digital transmission system, such as a 400 Mbit/s system using graded index or, if possible, single mode optical fiber should be introduced next. The optical fiber cable costs at which fiber systems become economical, depend upon the application area. For short and medium haul systems, 40¢ per meter per core is required, but $2 per meter per core is sufficient for large capacity, long haul systems. For a short haul system operating at approximately 1.5 Mbits/s or 6 Mbits/s, the advantages of its introduction greatly depend on optical fiber costs which should be less than 20¢per meter per core.     

基于磷酸盐玻璃微球腔的全光调谐光纤滤波器

提出并研究了一种基于磷酸盐玻璃微球腔的全光调谐光纤滤波器。利用自制的磷酸盐玻璃预制棒,以拉丝的方式制作出直径为200~500μm、纤芯-包层折射率差为0.004的磷酸盐玻璃光纤。利用大功率CO_2激光器熔融加热光纤制备出Q值达7.28×10⁵的微球腔。利用1550 nm波段的可调谐激光器,通过锥形光纤耦合方式激发微球腔内回音壁模式(WGM)共振,获得带宽约2 pm、插入损耗小于0.3 dB的耦合共振谱。在不同功率泵浦光的注入下,磷酸盐玻璃微球腔具有比普通石英微球腔更高的光敏感特性。实验结果表明:当微腔泵浦光功率增加时,磷酸盐玻璃微球腔内的WGM共振谱向短波长漂移(蓝移),光热调谐灵敏度约为72.727 pm/mW,线性度大于0.99;在相同光功率变化下,普通石英微球腔内的WGM共振谱向长波长漂移(红移),光热调谐灵敏度约为0.086 pm/mW,线性度较低。本文提出的磷酸盐玻璃微球腔全光调谐滤波器具有全光控制、结构紧凑、稳定性好、超窄带宽和调谐效率高等优势,在光纤传感和光纤通信等领域具有重要应用。     

A novel high birefringence equal diameter circular-hole photonic crystal fiber

A novel equal diameter circular-hole photonic crystal fiber (PCF) with high birefringence is proposed and numerically analyzed by employing the finite-element method. The proposed PCF’s birefringence is 10-3, which can reach 2 orders higher than that of traditional high birefringence fiber, and this equal diameter circular-hole structure reduces the difficulty of the actual drawing process. The effect of different parameters on the birefringence of this PCF is investigated, and the application of the Sagnac interferometer based on fiber filling technology in temperature sensing is studied. The result shows that the high birefringence PCF can be used in both optical communication and optical sensing fields.     

Strategies and technologies for planning a cost-effectivesurvivable fiber network architecture using optical switches

A 1:1 diverse routing protection switching architecture using optical protection switches to reduce costs for providing 1:1 (i.e. 100%) protection against fiber cable cuts is proposed. A cost analysis model is used to evaluate cost/survivability merits for 1:1 optical diverse protection architectures. Results show that the best place to deploy the 1:1 photonic diverse protection architecture in future networks is in spans carrying large DS3 demands, which are usually interhub spans. The proposed architecture can be implemented using electronically controlled low-speed single-mode fiber mechanical optical switches as protection switches to meet current performance and availability requirements     

A new compound modulation technique for multichannel analog videotransmission on fiber

An analog transmission technique for multichannel TV transmission on fiber using frequency-modulated/time-division multiplexing (FM/TDM) is described and compared with present digital and analog systems. Analysis and simulations indicate that the proposed system has a very low sensitivity to nonlinearities, similar to digital systems, and much better than current frequency-modulated/frequency-division multiplexed (FM/FDM) systems. This permits the use of higher optical modulation depth (as high as digital systems), which results in achieving high signal-to-noise ratio, large power budget, and/or the use of lower cost optical components. Furthermore, a better spectrum efficiency is possible     

用分段采样啁啾光栅实现谱相位编码

设计并实现了基于采样光纤光栅的光码分多址(OCDMA)谱相位编解码器.根据等效啁啾原理,采用分段采样啁啾的方法将宽谱光源的不同频率分量在时域上分离并重新组合,并将地址码信息用等效相移的方式引入到不同的频率分量上实现谱相位编码.采用该方法制作的编解码器具有制作简单、工艺要求低的特点,便于系统应用.对该编解码器的性能进行了计算机仿真并与实测数据进行了对比,结果显示该编解码器具有较好的性能.     

Silica-air double-clad optical fiber

A new design of the silica-air double-clad optical fiber is proposed. The fiber was prepared from an MCVD preform inserted into a supporting silica tube with a fluorine-doped connective element with a lower refractive index (Δn~-4×10^-3) and air as the second cladding. A numerical aperture as high as 0.3 was measured for the first cladding and for fiber lengths up to 50 cm. Although it is realized that the results are preliminary, the optimization of the fiber parameters promises a new all-glass design for double-clad optical fibers for high-power fiber laser applications     

Evanescently coupled photodiodes integrating a double-stage taper for 40-Gb/s applications-compared performance with side-illuminated photodiodes

The design, fabrication, and performance of double-stage taper photodiodes (DSTPs) are reported. The objective of this work is to develop devices compatible with 40-Gb/s applications. Such devices require high efficiency, ultrawide band, high optical power handling capability, and compatibility with low-cost module fabrication. The integration of mode size converters improves both the coupling efficiency and the responsivity with a large fiber mode diameter. Responsivity of 0.6 A/W and 0.45 A/W are achieved with a 6-/spl mu/m fiber mode diameter and cleaved fiber, respectively, providing relaxed alignment tolerances (/spl plusmn/1.6 /spl mu/m and /spl plusmn/2 /spl mu/m, respectively), compatible with cost-effective packaging techniques. DSTPs also offer a wide bandwidth greater than 40 GHz and transverse-electric/transverse-magnetic polarization dependence lower than 0.2 dB. Furthermore, a DSTP saturation current as high as 11 mA results in optical power handling greater than +10 dBm and a high output voltage of 0.8 V. These capabilities allow the photodiode to drive the decision circuit without the need of a broad-band electrical amplifier. The DSTP devices presented here demonstrate higher responsivities with large fiber mode diameter and better optical power handling capabilities and are compared with classical side-illuminated photodiodes.     

OPCI系统不同掺杂截面EYDFA增益瞬态的比较

为了研究分组与线路集成系统中突发模式大功率Er/Yb共掺光纤放大器(EYDFA)的瞬态性能,在函数极限的基础上采用迭代算法,建立了基于非线性方程速率方程的、不同掺杂截面EYDFA增益瞬态的比较模型,分析比较了有/无反馈条件下,不同掺杂截面的光分组(OPS)和光线路交换(OCS)输出信号的增益瞬态.结果表明,无反馈条件下,纤芯直径为4.6m的EYDFA,其OPS和OCS输出信号功率漂移小于纤芯直径为3.6m的EYDFA,功率漂移的改善约为12%;带反馈条件下,增大掺杂光纤直径,弛豫振荡导致的EYDFA增益抖动随之减小.故增大掺杂光纤直径,能有效抑制EYDFA反馈环路的弛豫振荡.     

Design and performance of nonmetallic optical fiber cable with high-impact-resistant sheath

A nonmetallic optical fiber cable which contains fiber ribbons inserted into slots is proposed. The cable has a high-impact-resistant sheath which affords protection against shotgun pellets. The antiballistic performance and cable diameter are investigated experimentally, and an optimum combination of thicknesses for the protective layer and outer polyethylene sheath is obtained. Based on the results, a nonmetallic 100-fiber cable with a high-strength protective sheath was manufactured, and its performance was evaluated. Excellent transmission, mechanical, and antiballistic characteristics were confirmed.<>     

熔石英棒和光纤构成的新型复合型相位共轭镜

提出一种使用熔石英棒和光纤构成的新型复合型相位共轭装置,并在实验中得以实现.这种组合将具有高的激光损伤阈值的大直径熔石英棒和具有较低的受激布里渊散射(SBS)阈值的光纤结合在一起,构成了振荡-放大形式的双池式受激布里渊散射结构,使得从光纤受激布里渊散射反射的斯托克斯光注入到熔石英介质中形成了强迫受激布里渊散射过程.在这种机制下,该复合型相位共轭镜较之单块熔石英棒、单根光纤或组合芯径光纤这三种形式的相位共轭镜,具有更低的受激布里渊散射阈值和更高的受激布里渊散射反射率,而且可以在较高的输入功率下运行.实验中将其用于高重复频率高功率的激光二极管(LD)抽运激光主振荡放大(MOPA)系统中,在100 Hz重复频率下获得了42.05%的反射率,并且获得了很好的光束质量,光束质量因子M2值从输入光束的3减少到1.6,反射光斑稳定.在400 Hz下光束质量因子M2值达到1.7.     

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.     

用于测量折射率的光纤迈克尔逊干涉型传感器

提出了一种基于单模光纤-四芯光纤-薄芯光纤(SMF-FCF-TCF)迈克尔逊干涉结构的折射率传感器。采用直接熔接的方式将各光纤进行熔接,由于各光纤之间纤芯的直径不匹配,因此在光纤的熔接处会发生光的激发和耦合。薄芯光纤端面涂覆有一层银面反射膜并用紫外固化胶进行保护来增强光在端面的反射率。四芯光纤作为传感结构中的耦合器,激发了更多的光进入薄芯光纤的包层中,提升了传感器的灵敏度。对传感器的折射率和温度传感特性分别进行了实验探究,实验结果表明,在折射率1.3333~1.3794范围内的灵敏度为137.317 nm/RIU,线性度为0.999,并且温度对传感器的影响较小。该传感结构熔接方式简单,在折射率测量领域具有一定的应用前景。     

Temperature-insensitive sensor for glucose brix measurement based on compact spindle-shaped structure with two-mode fiber

A temperature-insensitive sensor for glucose brix measurement based on compact spindle-shaped structure with two-mode fiber (TMF) is proposed. Due to the bending of optical fiber caused by flame baking, some of the light energy transmitted in the core leaks into the cladding area as an evanescent wave, which excites the higher-order cladding mode of the sensor. The experimental results show that when the length of TMF is 3 cm and the bending diameter is 4 mm, the maximum glucose brix sensitivity of the sensor is 0.368 nm/% from 0 to 21%. The sensor is insensitive to temperature from 10 °C to 50 °C, which can avoid the problem of temperature cross-sensitivity. A compact spindle-shaped sensor is a potential effective sensor with a simple structure, easy fabrication and low cost. The sensor can be used to detect glucose content in areas such as crops quality assessment and the research of pharmacy and bioengineering.     

可实现多点测量的波分复用光纤氢气传感系统

随着实际应用的发展,核电站、飞行器发动机、气体燃料等领域均提出了进行大数量点数氢气监测的要求,但目前已有的光纤氢气传感系统仅能实现单点测量。为解决上述问题,将波分复用技术和光纤氢气传感技术相结合,设计了一种可实现多点测量的波分复用光纤氢气传感系统,阐述了该系统的基本原理、光路结构和技术优势,并从理论上分析了进行多点氢气监测的可行性。根据理论分析的结果,基于已有器材搭建了一套4通道的波分复用光纤氢气传感系统,同时设计了一套实验装置并利用该装置对传感系统进行了验证实验。通过对光纤链路各节点传输光光谱和传感头反射信号光功率的测试,验证了所提出的新型氢气传感系统不仅可以实现多点测量,而且各测点具有较好的独立性和性能,一小时内测量稳定性优于1%,测量范围达到了0～4%,基本误差优于2%。理论分析和实验结果对于研究大数量点数氢气测量技术及系统极具参考意义。     

大内径离轴光纤旋转连接器的设计与实现

为了实现旋转系统之间的光信号耦合,设计了一 种新型的大内径离轴光纤旋转连接器。 将光纤准直器 和红外直角棱镜按照一定的规则排布在法兰盘上,使光信号能在较大离轴偏移量下保持持续 传输状态。分 析了影响离轴光信号传输耦合效率的主要因素,通过优化热扩芯光纤(TECF)准直器和红外直 角棱镜进一步减小了 离轴光纤旋转连接器的耦合损耗。研制的离轴光纤旋转连接器法兰盘内径为60mm, 内外法兰盘上的TECF准直器分别为16个, 并行光收发器实现串行光信号的收发。实验结果表明,本文的离轴光纤旋转 连接器在60RPM的转速和1.25Gbit/s的光信号 传输速率下最大插入损 耗为21.73 dB,可以满足旋转系统之间稳定传输光信号的要求。     

可实现多点测量的波分复用光纤氢气传感系统

随着实际应用的发展,核电站、飞行器发动机、气体燃料等领域均提出了进行大数量点数氢气监测的要求,但目前已有的光纤氢气传感系统仅能实现单点测量。为解决上述问题,将波分复用技术和光纤氢气传感技术相结合,设计了一种可实现多点测量的波分复用光纤氢气传感系统,阐述了该系统的基本原理、光路结构和技术优势,并从理论上分析了进行多点氢气监测的可行性。根据理论分析的结果,基于已有器材搭建了一套4通道的波分复用光纤氢气传感系统,同时设计了一套实验装置并利用该装置对传感系统进行了验证实验。通过对光纤链路各节点传输光光谱和传感头反射信号光功率的测试,验证了所提出的新型氢气传感系统不仅可以实现多点测量,而且各测点具有较好的独立性和性能,1小时内测量稳定性优于1%,测量范围达到了0~4%,基本误差优于2%。理论分析和实验结果对于研究大数量点数氢气测量技术及系统极具参考意义。