Wavelength division multiplexed loop buffer memory based optical packet switch

Photonic all-optical switching is widely considered as one of the technique to utilize the enormous optical bandwidth. Optical packet switching provides high speed, data rate transparency, data format transparency, efficient use of bandwidth and flexibility. To resolve the conflict during contention, packets are needed to be buffered. Due to the lack of optical RAM, fiber delay lines (FDLs) are the most suited option to buffer the packets. This paper proposes new optical packet switch architecture alongwith feedback shared buffer utilizing the advantage of WDM loop buffer memory. The loop buffer module used in this switch architecture is a new approach towards WDM buffering of packets. The mathematical modeling is done to validate the results obtained from simulation.     

AWG and EDFA based optical packet switch using feedback shared loop buffer memory

Optical packet switching provides high speed, data rate/format transparency, efficient use of bandwidth and flexibility. The major problem in the implementation of “all-optical” switching is contention which occurs when two or more packets arrive at the same time for the same destination. To resolve the contention, we have proposed an optical packet switch architecture based on WDM loop buffer memory in the feedback configuration. In that architecture, the contending packets are stored in a loop buffer module, and routed in the free time slots. The buffering duration in the recirculating loop is limited by a circulation limit. The analysis was been done to obtain the maximum number of allowed circulations. This paper proposes improved version of that optical packet switch architecture, to increase the number of maximum allowed circulations. The modification is done either by adding an extra erbium doped fiber amplifier (EDFA) in the original switch or by replacing the core space switch with arrayed waveguide grating (AWG). The performance analysis has been done by the simulations.     

Fiber optic aerial cables

While conventional cable elements can tolerate strains on the order of 1%, optical fibers cannot. As aerial cables may suffer contraction and elongation from low temperatures and high ice or wind loads, or high temperatures, respectively, proper designs have to provide the cables with length margins within which the fibers are protected against mechanical loads, except for a very limited bending stress. The well-suited loose tube buffer design, the way of calculation, and a list of reference cable plants are presented.     

光纤声传感器研究

基于光纤的弯曲损耗原理,设计了一种新颖的光强度调制型声波传感器。与同类光纤声传感器相比,有更高的声光转换效率。     

Fiber optic aerial cables

While conventional cable elements can tolerate strains on the order of 1%, optical fibers cannot. As aerial cables may suffer contraction and elongation from low temperatures and high ice or wind loads, or high temperatures, respectively, proper designs have to provide the cables with length margins within which the fibers are protected against mechanical loads, except for a very limited bending stress. The well-suited loose tube buffer design, the way of calculation, and a list of reference cable plants are presented.     

Fiber optic sensor interface standardization

The need for a new avionic interconnection scheme that can provide superior performance, installability and maintainability as compared with copper has become evident. Fiber optics, which has been proposed for this role, is expected to improve environmental immunity, decrease system weight, and increase bandwidth. It has also been suggested that sensors based on fiber optics can offer significant advantages in aerospace applications. Realizing these advantages is a difficult challenge because mature sensing technologies have done a good job at reasonable cost. Furthermore, it has been demonstrated that a wide variety of aircraft electrical sensors can be addressed by a few standard interfaces. Therefore, future fiber optic sensor suites will also need to be interrogated through only a few standard interfaces, and standardization of the fiber optic sensor interface will be a primary issue in furthering fiber optic sensing technology for aerospace applications. This paper discusses the fiber optic sensor standardization process underway in the Avionic Systems Division of the Society of Automotive Engineers.     

Optically controlled loop buffer using a SOA loop mirror and a circulator based reflector

In this paper, an optically controlled loop buffer is proposed and experimentally demonstrated. It utilizes a semiconductor optical amplifier (SOA) based loop mirror as a fast switch to realize the writing and reading of packets within this buffer and a circulator based optical reflector to achieve internal re-circulations. By adding fibers with different lengths between the loop mirror and the circulator, variable delay time per circulations can be obtained. We also demonstrate the performance of the 2.5 and 10 Gb/s data packets in this buffer structure, as well as the influence of the two different control signal formats on the packet signal degradation during buffering. This loop buffer has the merits of low cost and improved performance compared to other similar loop buffer structures. According to the obtained results, the achieved number of circulations is greatly increased.     

A Differentiating Fiber-optic Ring Interferometer

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Fiber optic data busses for aircraft

A variety of fiber optic data busses is being developed for aircraft applications. This article addresses five different data busses under consideration for both military and commercial aircraft. The impact of data bus protocol on component design, the effect of data bus topology on power budget and installation issues, and overall data bus performance are discussed.     

Fiber optic cables for undersea communications

Areas for potential use of low-loss optical fibers in undersea communications are discussed, along with constraints that should be satisfied in incorporating these fibers into practical cables. Recent progress in construction of optical cable units with low attenuation, small diameter, low specific gravity, high tensile strength, and extended flexural endurance is described. Design concepts for six undersea optical cables, with a variety of diameters and capabilities, are presented in detail. Guidelines are discussed for the design of such cables. Related operational requirements on the cable, such as power transfer, are examined to show how unconventional approaches can allow advantages of the optical data link to be more fully utilized.     

Fiber optic cables for undersea communications

Abstract

Areas for potential use of low-loss optical fibers in undersea communications are discussed, along with constraints that should be satisfied in incorporating these fibers into practical cables. Recent progress in construction of optical cable units with low attenuation, small diameter, low specific gravity, high tensile strength, and extended flexural endurance is described. Design concepts for six undersea optical cables, with a variety of diameters and capabilities, are presented in detail. Guidelines are discussed for the design of such cables. Related operational requirements on the cable, such as power transfer, are examined to show how unconventional approaches can allow advantages of the optical data link to be more fully utilized.     

Fiber optic data busses for aircraft

Abstract

A variety of fiber optic data busses is being developed for aircraft applications. This article addresses five different data busses under consideration for both military and commercial aircraft. The impact of data bus protocol on component design, the effect of data bus topology on power budget and installation issues, and overall data bus performance are discussed.     

Single-longitudinal-mode Brillouin fiber laser incorporating an unpumped erbium-doped fiber loop

A long-cavity single-longitudinal-mode (SLM) Brillouin fiber laser is firstly demonstrated by utilizing an unpumped Erbium-doped fiber (EDF) loop. The utilized EDF enables to form a self-induced ultra-narrow grating filter, and thus guarantees the SLM operation.     

Fiber optic beam delivery for endoscropic holography

Fiber optic methods to deliver the object and reference beams in endoholography are described. Two novel approaches are introduced, and quantitatively compared along with two other methods, on the basis of stability, power efficiency, and maximum power density. A method utilizing a three-layer coaxial fiber structure is shown to be most promising. Preliminary holograms have been obtained with a commercial single-mode fiber, the object beam being coupled out of the cladding by a bend in index-matching liquid.     

PMD mitigation using 3R regeneration based on EAM with wavelength conversion

Polarization mode dispersion (PMD) mitigation is performed using an optical 3R (re-amplification, re-shaping, re-timing) regenerator based on electro-absorption modulator (EAM) with wavelength conversion.System performance without and with 3R regeneration was separately studied by eye analysis and bit-error rate (BER) measurements. The signal quality was significantly improved by 3R regeneration under serious first order PMD (up to 40% of the bit interval) combined with second order PMD (up to about 520 ps2).The PMD mitigation margin of the proposed method is also investigated by measuring the sensitivity at BER 10-10. Further studies indicate that 3R regenerators have the potential to combat with the effects of PMD combined with polarization dependent loss (PDL) and polarization hole-burning (PHB).     

闭环光纤陀螺死区及光功率交扰误差的研究

数字闭环光纤陀螺引入的死区问题限制了其向更高性能惯性导航系统的应用。采用数学模型分析了数字闭环光纤陀螺死区的成因是反馈相关误差干扰,通过simulink仿真工具对死区现象进行了仿真,对比陀螺死区测试对模型进行了验证。以此为基础提出了电光合串扰造成死区的干扰模式,分析了干扰误差源的信号频域特征并使用频谱分析仪对受干扰的光功率信号进行了相关频点的测试,同时对比了干扰抑制后无死区的光功率信号相关频点的测试结果。通过抑制相关误差前后的测试结果对比,验证了与数字闭环反馈阶梯波相关的误差输入是死区形成的根本原因,除了电路交叉耦合之外,电路对光强的调制干扰也会造成死区问题。在采用针对干扰信号频率特性的退耦及PCB设计后,闭环光纤陀螺死区由0.2/h降低至0.02/h,满足系统应用需求。     

Fiber optic transversal filters for RF direction finding

A wide-band electro-optic direction-finding (DF) processor employing a network of fiber optic delay lines is described. This DF filter offers a potential instantaneous bandwidth of 20 GHz and allows for multiple, simultaneous beam-angular responses with peaks that are independent of frequency. Preliminary results of an eight-laser feasibility test model DF device with two transversal filters show good agreement between predicted and measured angular responses. This experimental matched-delay filter operates in the 200–1,000 MHz frequency range and can simultaneously monitor two angles of arrival. The laboratory results obtained in this investigation suggest that the fiber optics matched-delay filter can be useful for wide-band direction finding.     

基于湍流振动的光纤干涉仪流量计的研究

针对石油测井中流量是确定石油生产和传输特性极其重要的参数,提出一种非浸入式光纤干涉仪流量测量方法。在油管外壁紧密缠绕传感光纤,当流体流过管壁时可由湍流产生振动,引起管壁的动态压力变化,导致传感光纤内的传输光相位发生变化, 通过检测光相位的变化就可以获得相应的流量。在实验中找出管壁的振动频率特性,在此频率特性范围内确定出由湍流诱发的管壁振动加速度脉动值的标准方差与平均流量的量化关系,实现了5 m3/h~50 m3/h流量实时在线测量。     

Fiber optic transversal filters for RF direction finding

A wide-band electro-optic direction-finding (DF) processor employing a network of fiber optic delay lines is described. This DF filter offers a potential instantaneous bandwidth of 20 GHz and allows for multiple, simultaneous beam-angular responses with peaks that are independent of frequency. Preliminary results of an eight-laser feasibility test model DF device with two transversal filters show good agreement between predicted and measured angular responses. This experimental matched-delay filter operates in the 200-1,000 MHz frequency range and can simultaneously monitor two angles of arrival. The laboratory results obtained in this investigation suggest that the fiber optics matched-delay filter can be useful for wide-band direction finding.