四通道单模光纤旋转连接器的研制

设计了一种基于道威棱镜的光传输特性的四通道单模光纤旋转连接器,采用锥齿轮行星轮结构实现光信号的旋转耦合,并设计了耦合调整方案;分析道威棱镜光轴与旋转轴不重合带来的耦合损耗,确定道威棱镜的装调精度。最终使四通道单模光纤旋转连接器的技术指标达到了国外同类产品水平,且道威棱镜的通光孔径大,可在结构尺寸不变的情况下直接扩展为八通道单模光纤旋转连接器。     

基于SOI光波导的损耗测试与优化

利用电子束光刻技术,制备了带有氧化硅包层的SOI光波导结构,对其传输模态及损耗进行了详细的理论分析,并分别对波导的传输损耗和耦合损耗进行了测试.测试结果验证了单模传输模态时的传输损耗较低,在波导层上添加覆盖层可以将波导传输损耗降低至3.96dB/cm,利用光栅垂直耦合可以大大降低光纤-波导的耦合损耗,耦合效率可以达到32.7%.     

多模光纤损耗测试的误差因素分析

损耗是多模光纤最重要的指标,精确测量光纤损耗不仅要考虑测量中存在的各种误差,还要考虑模式耦合的影响。本文分析了各种误差对测量结果的影响及其与光纤长度的关系.1.模式误差σ_(?)模式误差与光纤的微分模式损耗(DML)有关,DML 大的光纤模式误差也大。这项误差常被称为暂态误差,它一般只存在于光纤输入端的一段距离内,随着模式分布趋于稳态,这项误差就逐渐消失.但是就一根较长的光纤整     

光纤与有机聚合物脊形波导的耦合损耗分析

光纤与有机聚合物脊形波导的耦合是有机聚合物波导器件封装中关键的一步,它直接影响器件的插入损耗.本文利用广角有限差分束传播法和有效折射率法对光纤与有机聚合物脊形波导的耦合损耗进行分析,得出了如下结论:1)耦合损耗随着错位、间隙、夹角的增大而增大;2)因错位而引起的耦合损耗在所有耦合损耗中占有主要位置.     

弹载光纤陀螺旋转惯组误差自补偿技术

目前弹载惯性测量组合测试标定精度受外界干扰影响较大,特别是光纤陀螺温度稳定性低,易受环境温度影响参数变化,导致误差补偿效果不好。针对该问题,提出设计一种光纤陀螺旋转惯性测量组合。在惯性测量组合外加旋转轴,在导弹飞行过程中使惯性测量组合绕旋转轴连续旋转,将射前补偿不完全误差调制为周期项,从而达到误差自补偿的效果。理论分析和仿真结果表明,通过旋转不仅能自动补偿与转轴垂直方向惯性仪表的常值误差和部分安装误差,而且能补偿加速度计部分一次项误差、二次项误差和部分交叉轴耦合项误差,选择合适的旋转方案还可以完全消除旋转速度与陀螺仪标度因数误差、安转误差的耦合误差。     

氢与光纤的物化反应对井下永久性测量的影响

用于井下永久性测量的光纤传感器,由于在高温高压等恶劣环境下会与井下物质发生各种反应从而引起光纤吸收损耗的增加.为了掌握井下永久性测量用光纤吸收损耗的增加情况,本文针对影响光纤吸收损耗的重要因素-氢与光纤的物理及化学反应进行了研究,分析了其影响机理,讨论了其对光纤测量性能及使用寿命的影响,仿真计算了氢与光纤发生的各种反应所导致的光纤吸收损耗的增加情况,得到了化学反应引起的吸收损耗增加是影响永久测量性能的主要因素的结论,并由此给出了有效减少氢对光纤井下永久测量影响的预防措施.     

熔锥型光纤声光可变衰减器

利用耦合模理论对光纤熔锥声光器件进行了数值模拟,得到了全光纤声光衰减器传输谱和可调谐性。分析了带宽与声波长、耦合长度的关系。数值分析结果表明,声波在光纤熔锥中引起的轴向电介质微扰、耦合长度和工作波长都会对器件的传输谱产生影响,选择合适的设计参数可以制作较为理想的声光衰减器。实验上获得了损耗小于0．2dB,带宽大于200nm,动态范围为20dB的单模光纤熔锥可变衰减器,所得结果与理论分析相符合。这种器件可用于光纤通信及光纤传感。     

光纤冷压端接工艺技术研究

本文结合我公司目前所使用的光纤连接器的结构特征,重点分析了该类连接器端接夹具的设计和研磨参数的计算,最后根据该类连接器的结构特征设计了相应的检测仪器。本课题在光纤端面加工工艺所涉及的相关技术和检测仪器的研究,对提高光纤连接器端面加工质量,改善光纤连接器性能以及光纤连接器端接工艺的研究具有实际意义。     

用于全站仪检定之棱镜的精确定位及控制装置研究

本研究涉及一种用于检定全站仪的棱镜精确定位控制装置及方法,它依靠轴承组件与棱镜安装组件的重力作用,实现棱镜的精确定位,避免了全站仪旋转电机自身的设备误差给棱镜定位带来影响.本文就该定位控制装置的结构及方法,进行试验和分析,结果表明,采用本装置实测,使测量结果得到了改进,数据更加精准.     

高斯光束到光纤的单透镜耦合

分析了基模高斯激光束到单模和多模光纤的单透镜耦合过程中的各种损耗,把多模光纤的光场用高斯分布近似,采用模场耦合理论计算了基模高斯光束到单模和多模光纤的单透镜耦合效率.模拟计算了当激光-光纤耦合系统的工程参数(光束束宽、光纤数值孔径和光纤的纤芯芯径)一定时,单透镜耦合效率与所选用透镜的焦距之间的关系.并利用532mn激光(M2≤1.05)在几种不同焦距的透镜下对纤芯直径为3.μm的单模光纤和25μm的多模光纤进行了耦合效率的测定实验,得到了与理论计算基本吻合的实验结果.     

Dove prism with increased throughput for implementation in a rotational-shearing interferometer

An analytical expression is derived for the tilt introduced into a wave front by a Dove prism with manufacturing errors in the prism's base angles and pyramidal angle. We found that the tilt decreases when the base angles are increased above the values of traditional design. The increase in the length-aperture ratio of a prism is detrimental to the prism's performance. However, a Dove prism with a widened aperture increases throughput and maintains a manageable prism weight for implementation in a rotational shearing interferometer. Thus we propose a Dove prism designed with a widened aperture to increase throughput in a rotational shearing interferometer and with larger base angles to minimize the wave-front tilt introduced by manufacturing errors. Experimental results implemented in a rotational shearing interferometer demonstrate the feasibility of this design.     

基于光学定心加工的道威棱镜装配方法

本论文针对如何实现道威棱镜光轴与旋转轴平行,将道威棱镜转像理论与光学定心加工结合,提出了基于光学定心加工的道威棱镜组件装配方法.该方法根据道威棱镜旋转轴偏转时其出射光束发生变化的特性确定道威棱镜光轴,并通过车削的方式保证其镜筒外圆旋转轴与其光轴平行.本文具体提出两种道威棱镜组件定轴方案,分别为平行光管定轴方案以及激光定...     

Dove prisms and polarized light

Abstract

A Dove prism inverts the transmitted image and, when rotated, rotates the image at twice the rotation frequency of the prism. However, although the image is rotated, for a wide range of design parameters the polarization state of the transmitted light is not rotated. This has important implications when using Dove prisms within laser cavities, interferometers and other optical experiments.     

Prism Coupling to Long-range Coupled-surface Modes

Abstract

Using the virtual mode theory for attenuated total reflection (ATR) experiments the long-range coupled-surface modes supported by symmetrically bound thin films have been examined to study the influence of prism coupling. Approximate analytic results show that in certain circumstances prism coupling may result in a decrease of mode loss from the unperturbed eigenvalue. This is well illustrated for the long-range surface exciton-polariton. Detailed numerical evaluations confirm the analytic results. The generally accepted conclusion that prism coupling always results in an increase in mode loss is thus not supported by these results which show convincingly that for more complex ATR geometries simplistic treatments are invalid.     

Image inversion and magnification by negative index prisms

A Dove prism and an anamorphic prism pair are investigated in negative index imaging systems. An equilateral triangular prism with refractive index of -1 operates as a negative index Dove prism that inverts as well as images the incident field. A negative index anamorphic prism pair acts as a negative index imaging system with magnification. The relationship between achievable magnification and aberrations is discussed. Both prism systems can be implemented by using negative index photonic crystals, and their performance is demonstrated numerically by the finite-difference time-domain method. These negative index prism structures enhance the functionalities of negative index flat lenses and broaden the applications of negative index materials.     

Image reconstruction in optical tomography in the presence of coupling errors

Image reconstruction in optical tomography is a nonlinear and generally ill- posed inverse problem. Noise in the measured surface data can give rise to substantial artifacts in the recovered volume images of optical coefficients. Apart from random shot noise caused by the limited number of photons detected at the measurement site, another class of systematic noise is associated with losses specific to individual source and detector locations. A common cause for such losses in data acquisition systems based on fiber-optic light delivery is the imperfect coupling between the fiber tips and the skin of the patient because of air gaps or surface moisture. Thus the term coupling errors was coined for this type of data noise. However, source and detector specific errors can also occur in noncontact measurement systems not using fiber-optic delivery, for example, owing to local skin pigmentation, hair and hair follicles, or instrumentation calibration errors. Often it is not possible to quantify coupling effects in a way that allows us to remove them from the data or incorporate them into the light transport model. We present an alternative method of eliminating coupling errors by regarding the complex-valued coupling factors for each source and detector as unknowns in the reconstruction process and recovering them simultaneously with the images of absorption and scattering. Our method takes into account the possibility that coupling effects have an influence on both the amplitude and the phase shift of the measurements. Reconstructions from simulated and experimental phantom data are presented, which show that including the coupling coefficients in the reconstruction greatly improves the recovery of absorption and scattering images.     

Improvements in the accuracy and the repeatability of long trace profiler measurements

Modifications of the long trace profiler at the Advanced Photon Source at Argonne National Laboratory have significantly improved its accuracy and repeatability for measuring the figure of large flat and long-radius mirrors. Use of a Dove prism in the reference beam path corrects phasing problems between mechanical errors and thermally induced system errors. A single reference correction now completely removes both of these error signals from the measured surface profile. The addition of a precision air conditioner keeps the temperature in the metrology enclosure constant to within +/-0.1 degrees C over a 24-h period and has significantly improved the stability and the repeatability of the measurements. Long-radius surface curvatures can now be measured absolutely with a high degree of confidence. These improved capabilities are illustrated with a series of measurements of a 500-mm-long mirror with a 5-km radius of curvature. The standard deviation in the average of ten slope profile scans is 0.3 microrad, and the corresponding standard deviation in the height error is 4.6 nm.     

Measurements of an ultra-low loss polarizer for λ = 1064 nm using a high finesse optical cavity

Abstract

We present experiments performed on a specially designed calcite polarizer based around a modified Nicol prism optimized for use at 1064 nm. The polarizer combines the physics of birefringence, Brewster's angle and total internal reflection to achieve a combination of close to zero insertion loss and high extinction ratio for one of the incident light polarizations, limited in theory only by absorption losses in the calcite. We describe optical cavity based measurements which reveal the loss properties to be around 220 ppm, setting an upper limit on the bulk absorptance of calcite at 1064 nm, and offering a polarizer with lower loss than high grade anti-reflection coated components.     

Jones matrix for image-rotation prisms

The polarization-transforming properties of rotational prisms are analyzed with polarized light by using the Jones calculus and the exact ray-trace. A general expression of the Jones matrix for a rotational prism is derived, incorporating an explicit dependence on the image-rotation angle or the wave-front-rotation angle. The Jones matrix for the Pechan, Dove, Reversion, and Delta prisms is derived where the explicit dependence on the angle of rotation of the image is given. An experiment with a rotating Dove prism is also conducted to determine the output states of polarization for incident linearly polarized light. Experimental results agree with theoretical expectations.