Low-loss coupling of multiple fiber arrays to single-mode waveguides

A method for obtaining permanent low-loss couping between arrys of single-mode fiber and Ti:LiNbO3waveguides is described. The technique, based on the use of silicon chip V-grooves, simplifies the coupling problem by simultaneously aligning the entire array and by providing a large surface area for a higher integrity adhesive bond. Atlambda = 1.3 mum, we measure an average 1.9-dB coupling loss (exclusive of propagation loss) for the assembled array. The average excess loss due to the fiber array is 0.8 dB. We present an analysis of the effect of various types of array misalignment on coupling efficiency. Angular alignment and array periodicity are found to be critical. If the fiber and waveguide periodicities are matched exactly, the fibers need only be placed withinpm 1.3mum of their optimum position to maintain coupling efficiencies greater than 90 percent.     

Measurement of the birefringence of UV-written channel silicawaveguides by magnetooptic polarization-mode coupling

We report the measurement of the birefringence in integrated-optical waveguides using magnetooptical coupling between the two principal polarizations of the fundamental mode. We demonstrate this measurement technique for directly ultraviolet (UV)-written channel waveguides in silica on-silicon and silica-on-silica. The dependence of the waveguide birefringence on the UV-writing power and UV polarization is investigated. The results are compared with the birefringence of etched waveguides in comparable material systems. An analytical formula for the form birefringence in buried channel waveguides is developed, and measured data are compared with theoretical results     

Low-loss dispersion-shifted single-mode fiber manufactured by the OVD process

The development of a low-loss dispersion-shifted single-mode fiber with a segmented-core profile is reported. The combination of low dispersion in the 1550-nm window, 0.21-dB/km median attenuation at 1550 nm, excellent bend resistance (lambda_{c} = 1200nm), and good splicing behavior make this fiber an economically viable alternative for long-haul high-data-rate operation utilizing multilongitudinal mode lasers. System experiments have demonstrated bit rates as high as 1.3 Gbit/s over 107 km and repeaterless spans of up to 233 km.     

Low-loss fibre-chip coupling by buried laterally tapered InP/InGaAsP waveguide structure

A passive InP/InGaAsP spot-size transformer for low-loss coupling of semiconductor optoelectronic devices to single-mode fibres has been fabricated entirely on InP. Using a buried two-layer laterally tapered section, spot-size transformation is demonstrated from below 2 mu m up to 8 mu m, the spot size of a dispersion-shifted fibre at 1550 nm. For a chip without antireflection coating a total insertion loss of 2.7 dB was achieved at a taper length of approximately 600 mu m.<>     

Determining the mode-field diameter of single-mode optical fiber: An interlaboratory comparison

The National Bureau of Standards, in cooperation with the Electronic Industries Association, conducted an interlaboratory measurement comparison among fiber manufacturers. Evaluated were transverse splice offset, near-field, far-field, and variable aperture far-field methods for determining mode-field diameter. Measurements were performed on five single-mode fibers at both 1300- and 1550-nm wavelengths. At 1300 nm, agreement was fairly good with the average one standard deviation being 0.15 μm for mode-field diameters in the8-11 mum range. Distinct systematic differences among various techniques were observed at 1550 nm where mode distributions are not as Gaussian.     

Low-loss fiber-chip coupling by InGaAsP/InP thick waveguides forguided-wave photonic integrated circuits

A generic waveguiding structure is reported with low coupling loss (⩽1 dB/facet) with lensed fibers and low propagation loss (⩽1 dB/cm). This structure is suitable for low loss guided-wave photonic integrated circuits including active elements such as switches, and passive interconnections such as mirrors, and allows low polarization dependent operation. Which is required for instance in wavelength demultiplexers. This structure based on a single epitaxy is of interest for low cost photonic switching fabrics     

基于硫系光纤交叉相位调制的波长转换研究

全光波长转换器(AOWC)是全光通信网络的关 键器件,它是实现光波长路由的必要手段。本文提出了一种 基于硫系光纤交叉相位调制的波长转换方案。将信号光和探测光同时输入普通硫系光纤产生 XPM,然后用光带通滤波器(BPF) 滤得转换光的单个边带,从而实现相位-强度转换,还原出数字信号。本文详细分析了系统 的工作原理,并通过仿真,验证了 方案的可行性。该方案只需1m长度的光纤就能产生显著的XPM,对输入光信号峰值功率的要 求低,信号光可由40 Gb/s的归 零码数字信号驱动MZM调制获得,而不需要特殊的高功率超短脉冲激光。波长在1550 nm处的转换光信号眼图性能良好, 与原始信号相比,只有大约1dB的功率代价。该系统的波长转换的距离可达25 nm。该方案实现简单,不需要因为色散对硫 系光纤做特殊处理,适合于高速光传输系统,具有极大的应用前景。     

耦合器衰减实现的两种全光波长变换

在以往对全光波长变换的研究中,都是利用变换光实现波长变换,而利用闲频光的全光波长变换还没有相关报道.文章通过模拟耦合器衰减对全光波长变换的影响,发现在不同的泵浦光与信号光功率条件下,调节耦合器衰减可分别实现利用变换光的全光波长变换和利用闲频光的全光波长变换.     

Multiple-wavelength conversion with gain by a high-repetition-rate pulsed-pump fiber OPA

The authors propose and demonstrate a novel multiple-wavelength converter with gain, based on a pulsed-pump fiber optical parametric amplifier (OPA). It generates multiple replicas of the signal, as well as spectrally inverted versions. The device is modeled by using quasi-steady-state OPA gain equations, as well as by the split-step Fourier method. Predicted conversion gains of up to 20 dB have been confirmed by experiments. A 10-Gb/s nonreturn-to-zero (NRZ) input signal was converted into several replicas, with penalties ranging from 0.26 to 1.24 dB for frequency shifts of /spl plusmn/k/spl times/100 GHz (k=1, 2, 3, 4).     

ICCD的光纤耦合技术

文中主要介绍ICCD光纤耦合工艺技术的研究工作,并介绍了国内外相关技术的历史及发展现状。文中所述的ICCD的耦合工艺,继承了国肉研究的技术特点,同时,参考了国际上一些著名公司的相关技术,例如以色列的ORLIL公司、法国的PHOTONIS公司、荷兰的DEP公司和ADMEC公司、俄罗斯的ELECTRON公司等。因此,具有相当的先进性、代表性和参考价值。     

双环掺铒光纤激光器混沌的耦合反馈相移控制

提出了双环掺铒光纤激光器混沌耦合反馈相移控制方法和物理模型,利用耦合器将系统的输出量反馈到系统中,选取适当的反馈系数,并在反馈通道上加入相移控制器PC控制反馈光的相移,通过对反馈系数和反馈光相移的控制可以实时、动态、有效地控制激光混沌到稳定态和周期态;结合混沌耦合反馈相移控制方法和物理模型,建立了该控制模型的动力学方程;运用数值计算分析了系统输出状态随着控制参数变化的演化规律,表明控制参数反馈系数和反馈光相移的变化可以使系统的输出产生丰富的具有一定规律性的激光动力学现象;最后讨论了混沌被控制到单周期态时系统输出的振荡周期的变化规律与控制量的关系,在选取适当的控制参数,快速达到所需输出状态时,可以充分利用这一关系。     

多模光纤到单模光纤耦合效率的研究分析

由于多模光纤的纤芯直径远大于单模光纤的纤芯直径,且多模先纤的数值孔径也大于单模光纤的数值孔径,因此多单模转换效率极低.为了提高多模光纤到单模光纤的耦合效率,采用自聚焦透镜对从多模光纤出射的光束进行汇聚,使其半径大小尽量与单模光纤的芯径大小相匹配,然后再利用球透镜来减小被汇聚过的光束的发散角,在不考虑各种连接损耗的前提下,通过ZEMAX来求解多模光纤到单模先纤的耦合效率.采用这种新型组合透镜耦合的方法可以极大提高多单模耦合的耦合效率,其最高耦合效率可达到38.7%.因此,这种组合透镜法是可行的.     

Light coupling by a vortex lens into graded index fiber

This paper reports a novel launch scheme for coupling light into the skew rays of a graded index fiber. This is accomplished by utilizing a diffractive optical element in conjunction with a single mode fiber to mode match a graded index fiber. Results are used to confirm the fact that the element does improve the coupling into the skew rays of graded index fiber. This approach offers an alternative to existing methods based on tilting and angular offsets for the conditioned launch problem     

用于光纤耦合的无衍射光束研究

在光纤耦合理论及圆锥透镜产生无衍射光束理论的基础上提出了无衍射光束在光纤耦合中的方法.相对于其他方法,无衍射光束更容易耦合进入光纤,特别是单模光纤,并且在其最大准直距离内耦合效率几乎不变,可以减小装调难度.对此方法进行理论分析,并进行实验,加工了光纤耦合使用的圆锥透镜,其锥角为10°,通光半径为5mm.波长为0.632...     

两种LDA光纤耦合系统的比较研究

由于LDA本身的结构特点使其出射光束存在着大发散角、大像散等缺陷,采用LDA与光纤耦合的方式不但可以整形光束,还可以扩大LDA的应用领域.设计了LDA与微球端面光纤列阵和单根微球端面光纤耦合两种光束整形方式,分别进行了实验测试并分析了它们的输出特性.实验表明:利用LDA与微球端面光纤列阵耦合,可以实现31W的高功率连续激光输出,LDA与单根微球端面光纤耦合后出射的激光功率能够达到25W,光纤数值孔径为0.22.     

Frequency demodulation of a semiconductor laser by FM-AM conversion in an optical fiber

It is theoretically demonstrated that the FM light output of a semiconductor laser can be detected through FM-AM conversion using an optical fiber. The analysis is made in the case of narrow-band FM and for the fundamental mode in a step-index monomode fiber. It is shown that for a 10 GHz modulation frequency, the fiber length necessary to achieve maximum demodulation lies in the range of 10 km.     

单模光纤耦合控制器的LabVIEW程序设计

单模光纤耦合控制系统设计是全光纤激光雷达、光纤通信等领域的一个重要的前沿课题.基于LabVIEW开发环境完成了耦合控制器对三轴精密光学平台的精确自动控制,精度达到0.05微米,并实现了友好的仪器界面.实际应用表明,该系统具有操作简便、控制准确的特点,达到了设计要求.     

Microlens for efficient coupling between LED and optical fiber

A new fabrication method of a microlens is proposed that can be easily applied to optical devices and microlens systems. The proposed microlens is formed by self-surface tension and cohesion of UV curing material. Since the microlens is hardened by short time UV exposure, the fabrication process is very simple. Integration with surface emitting-light emitting diode (SE-LED) results in enhanced coupling to optical fiber with coupling efficiency larger than the conventional case by 1.5 times. We also made a hemispheric microlensed fiber using this method. Compared with a typical arc-lensed fiber and a flat-end fiber, the coupling efficiency is improved to 18% and 40%, respectively     

PPT光纤波片耦合模方程的解析解

理论分析了PPT光纤波片耦合模方程,得出了一定条件下的解析解,将该解析解和渐进近似结果进行了比较,它们在实际应用的PPT光纤波片中具有很好的一致性。     

Low-loss and high-extinction-ratio silica-based strictlynonblocking 16×16 thermooptic matrix switch

A low-loss and high-extinction-ratio silica-based 16×16 thermooptic matrix switch is demonstrated. The switch, which employs a double Mach-Zehnder interferometer switching unit and a matrix arrangement which reduces the total waveguide length, is fabricated with 0.75% refractive index difference waveguides on a 6-in silicon wafer. The average insertion loss and the average extinction ratio are 6.6 and 55 dB, respectively. The total power consumption is 17 W