Exciting the optical response of nanowire metamaterial films on the tip of optical fibres

This Letter reports on the assembly on the tip of an optical fibre of a metamaterial film fabricated by a self‐assembly bottom‐up method, composed of silver nanowires embedded in an alumina matrix. By illuminating the film through the fibre in a reflection configuration, we observe experimentally the optical response of the metamaterial in agreement with theoretical predictions and interpreted as the excitation of surface plasmon‐polaritons in the cylindrical surface of the nanowires. These results pave the way for low‐cost optical fibre devices that incorporate metamaterial films.

     

Nonlinear control of the propagation of optical pulses in doped optical fibers

Results of study of nonlinear processes occurring during the propagation of light pulses in optical fibers doped with atoms of rare-earth elements under conditions of atomic coherence and interference are presented. For a three-level Λ scheme of interaction, the linear (χ⁽¹⁾) and nonlinear (χ⁽³⁾) susceptibilities of such a medium are calculated. It is shown that the coefficients of Kerr nonlinearity and nonlinear absorption can reach extremely large values and can be negative. The competition between linear and nonlinear processes in the Λ scheme allows one to obtain compensation regimes when the coefficients of dispersion or absorption of the optical fiber material vanish. The efficient control of the optical properties of such a system over wide limits proves to be possible owing to variations in the parameters of light pulses at the input of the medium. The necessary conditions for realizing regimes with “slow” light, as well as for self-compression of a probing pulse on ultimately small spatial scales in a doped optical fiber, were obtained.     

Measurement of the optical absorption coefficient for liquid based on optical microfiber

An inline measuring method of the optical absorption coefficient for liquid based on optical microfiber (OM) is studied. If an OM is immersed into absorptive liquid, the additional loss of the OM will increase. We have analyzed the relationship between the additional loss of the OMs and the absorption coefficients of the liquids, and found that the OM with determinate construction will be useful for measuring the absorption coefficients of the liquid whose refractive index is lower than that of the OM. Two OM samples are prepared to measure the absorption coefficient of pure water. A supercontinuum source is launched into the OM sample which is immersed into pure water, and absorption spectrum from 1400 to 1700 nm has been achieved by monitoring the additional loss. The trend of the absorption spectrum is similar with that of the reported result, showing that the inline measurement of the optical absorption coefficient is a feasible method for those lower refractive index liquids.     

Physical processes upon the optical discharge propagation in optical fiber

Recent theoretical works on the physics of the fiber fuse effect in optical fiber are reviewed. A qualitative interpretation of the significant increase in the absorption of quartz glass with increasing temperature is presented. The results of the 2D simulation of the optical discharge propagation in optical fiber are analyzed. The results of the simulation are in agreement with the recent measurements of the spatial distribution of the bright-spot radiation intensity. It is demonstrated that the recently demonstrated fast propagation of the optical discharge can be interpreted as light detonation. A mechanism for the formation of a chain of cavities in the fiber-fuse track is considered. It is demonstrated that this effect cannot be interpreted using the Rayleigh capillary instability due to the relatively high viscosity of glass. The periodicity of the cavities can be related to an instability of a new type. A high-density double layer of charges emerges at the plasma-liquid interface. A tendency towards an increase in the surface owing to the repulsion of like charges provides for a development of the instability that causes the formation of the chain of cavities.     

Characterization of optical properties of optical polymers

Possible applications of polymer materials in optical systems and devices are defined mainly by their optical properties in terms of refractive indices, transmission, dispersion and thermo-optic coefficients. We have examined more than twenty types of optical plastics including basic, commercial and some new development materials. Detailed measured refractometric data and transmission spectra in the visible and near infrared regions are presented. Variation of refractive indices with temperature is considered to obtain the thermo-optic coefficients. Discussion on dispersion of studied optical polymers and comparison to glass is included on the base of a number of dispersive characteristics and curves.     

制导光缆中光纤寿命预期

介绍了光纤寿命预期的疲劳实验方法和筛选实验方法。采用这两种方法，利用电子万能材料试验机和光纤筛选复绕机对室温下光纤进行了疲劳性能实验。实验得出，在张力小于850g的情况下，制导光纤的寿命可以达到10年以上；光纤的韦伯参数md和疲劳参数nd的大小影响光纤寿命。实验表明，当光纤的使用状态受力较大时，或使用贮存状态相差较大时，宜选用动态方法进行寿命预期；当贮存和使用状态受力变化不大时，宜选用筛选复绕方法预期光纤寿命。制导光纤寿命模型宜选用动态疲劳模型，通信光纤可选用筛选实验模型。实验还表明，提高光纤的抗疲劳因子nd和减小光缆中光纤的应变，可以更好地保持光缆中光纤的使用寿命和可靠性。     

光镊系统中光放大倍数对测量结果的影响

从实验和理论两方面，讨论了在光镊系统中，光放大倍数在500—1000倍、间隔为100倍的范围内，对四象限探测器位移测量信号的幅值及其线性度的影响.实验结果与理论结果符合很好，得出相同的结论：当微粒的影像半径约为四象限探测器探头半径(50—60)%时，可以得到幅值大、线性好的输出信号. 关键词： 光镊系统 放大倍数 四象限探测器     

光纤端面的质量与光纤光学性能的关系

光纤的透过性能是光纤传输的重要特性之一。影响光纤透过性能的因素除了纤芯、包层玻璃的质量和几何缺陷以外,还与光纤端面的质量有关。在光纤的加工过程中,光纤端面的平整度、磨料的使用等都会影响端面的质量。讨论了影响光纤透过性能的因素;光纤端面的反射损失对透光性能的影响;增透膜对光纤端面反射的控制;加工后光纤端面的几何形状对透过性能的影响;加工后纤维端面折射率的变化情况;抛光液酸碱性的控制;抛光后光纤端面的处理。通过对光纤端面进行加工过程的控制和对光纤端面进行涂层的处理可改善光纤的透光性能。     

Temperature distribution in the bright spot of the optical discharge in an optical fiber

2D simulation of the optical discharge propagation in an optical fiber is performed. In contrast to the previous works, the temperature dependences of the transfer coefficient are taken into account for the bright-spot plasma. The results are compared with the recently published measurements of the spatial distribution of the bright-spot radiation intensity. Good agreement is obtained for the discharge propagation velocity and the dependence of the bright-spot size on the laser power.     

Influence of temperature on the optical and structural properties along the diameter of optical fibres

Multiple-beam Fizeau fringes technique with an opto-thermal device is used to study the effect of temperature on the optical properties of Philips graded-index optical fibres. The refractive index profile of the optical fibre is measured at different temperatures. From these profiles the opto-thermal coefficient, the profile shape parameter α, the cladding/core maximum refractive index difference Δn and some guidance parameters of the optical fibre that play an important role in communication are determined. The variation of oscillation and dispersion energies along the diameter of the optical fibre (energy profile) are calculated at different temperatures. An empirical formula of the energy profile is obtained. Microinterferograms are given for illustrations.     

利用光学薄膜模型研究垂直腔面发射激光器的光学特性

可以把垂直腔面发射激光器看作是多层光学薄膜,应用光学薄膜原理对其光学薄膜的特性进行了研究。计算分析了布拉格反射镜和谐振腔模的反射谱受器件结构变化的影响。通过利用菲涅耳系数矩阵法计算,得到了光在垂直腔面发射激光器器件结构中形成的驻波场分布。结果表明,利用菲涅耳系数矩阵法设计垂直腔面发射激光器的光学薄膜是一种快捷准确的方法。     

Remote optical control of an optical flip-flop

We experimentally demonstrate control of a holding-beam-enabled optical flip-flop by means of optical signals that act in a remote fashion. These optical-control signals vary the holding-beam power by means of cross-gain modulation within a remotely located semiconductor optical amplifier (SOA). The power-modulated holding beam then travels through a resonant-type SOA, where flip-flop action occurs as the holding-beam power falls above and below the switching thresholds of the bistable hysteresis. Control is demonstrated using submilliwatt pulses whose wavelengths are not restricted to the vicinity of the holding beam. Benefits of remote control include the potential for controlling multiple flip-flops with a single pair of optical signals and for realizing all-optical control of any holding-beam-enabled flip-flop.     

Performance of optical links with optical amplifiers

In this work a comparison between the performances of single and multichannel systems is reported for links with optical amplifiers, considering conventional and soliton signals, Time Division Multiplexing (TDM), and Wavelength Division Multiplexing (WM) techniques. The performance evaluation is obtained by means of numerical simulations taking into account the effects of the chromatic dispersion, the Kerr nonlinearity, and the ASE noise of the optical amplifiers. Both the regimes of constant and fluctuating chromatic dispersion along the link are studied. The possibility of implementing high-capacity optical systems for a high-bandwidth European network is evaluated.     

弱光反馈对相干光差分相移键控系统性能的影响

本文讨论了弱光反馈对相干光差分相移键控系统误码率的影响。指出:在适当的反馈条件下,弱光反馈可以改善系统的误码率性能。     

含非球面光学系统多功能光学设计程序

本FORTRAN程序普适于球面和含有非球面的光学系统.用它可在微机上完成包括自动设计和OTF计算在内的全部设计过程.自动设计子程序贯穿了复合优化思想;提出了新的病态处理方法;实现了自动设计与OTF评价的方便结合,与传统设计手段的方便结合.     

Rotation of single bacterial cells relative to the optical axis using optical tweezers

Using a single-beam, oscillating optical tweezers, we demonstrate trapping and rotation of rod-shaped bacterial cells with respect to the optical axis. The angle of rotation, θ, is determined by the amplitude of the oscillation. It is shown that θ can be measured from the longitudinal cell intensity profiles in the corresponding phase-contrast images. The technique allows viewing the cell from different perspectives and can provide a useful tool in fluorescence microscopy for the analysis of three-dimensional subcellular structures.     

Measurement of cross-phase modulation in optical materials through the direct measurement of the optical phase change

We measure the cross-phase modulation (XPM) nonlinear indices of optical materials resulting from the interaction of an ultrashort pump pulse at 800 nm with a weak ultrashort probe pulse at 400 nm through the direct measurement of the optical phase change, using frequency-resolved optical gating. The materials studied include fused silica (SiO(2)) , borosilicate glass (BK-7), beta-BBO , and KD(*)P . This method results in a XPM nonlinear index that is in agreement with calculations based on nonlinear indices from previous self-phase modulation measurements.     

Tomography of the near-field optical signal

In near-field optics, measurement of vertical variations of the near field is of great interest for characterizing the efficiency of resonances such as surface plasmon polaritons. The use of the signal obtained through the lock-in amplifier using a feedback on the vertical vibration of the probe is shown to enable the reconstruction of the near field without the use of the slower technique of approach curves. Therefore, a tomography of the near field is directly available.     

光学特异材料的设计(英文)

In this contribution we review our latest achievements of combined experimental and theoretical studies to tailor the properties of optical metamaterials(MMs) at will. We give three examples of metamaterial designs that have been realized by means of electron-beam lithography and whose spectroscopic characteristics have been comprehensively investigated. In every case, our experiments are complemented by rigorous numerical simulations. Particular emphasis is put on the significance of such tailored effectiv...     

多级石英晶体旋光光学滤波器的滤波特性

根据石英晶体的旋光色散特性,利用光学矩阵方法对多级石英晶体旋光光学滤波器的滤波原理进行了详细的理论分析,推导出多级石英晶体旋光光学滤波器的透射主峰波长和通带半宽度的计算公式.利用分光光度计对单级和多级石英晶体旋光光学滤波器的滤波特性进行了实验研究,结果表明单级和多级石英晶体旋光光学滤波器滤波特性与理论曲线一致.从理论和实验上证明了多级石英晶体旋光光学滤波器与单级相比通带半宽度得到了有效的压缩,且随滤波器级数的增大,压缩的程度也随之增大. 关键词： 光学滤波器 偏振 石英晶体 旋光色散