双通道光环形器结构的设计及理论分析

提出了一种双通道式多功能光环形器，在结构设计中插入了双尾纤及透镜对，实现了器件功能复用，降低了制造成本与占空比。在理论上用琼斯矩阵对光环形器的插入损耗及隔离度等性能参数进行分析，探讨了影响该双通道光环形器隔离度、插入损耗特性的因素，结果表明，双通道多功能光环形器在器件镀增透膜的基础上具有与传统单通道光隔离器相同低插入损耗和高隔离度等特性。     

LD激光与单模光纤耦合时的失准容忍度分析

本文导出了ＬＤ激光与带端面微透镜的单模光纤直接（ＳＭＦ）耦合时的失准容忍不变量－失准容忍面积。并指出横向与角向的中心失准容忍度分别与ＬＤ的模斑尺寸、ＳＭＦ模斑对应的远场发散角成正比；而横向和角向的最大失准容忍量却分别与ＳＭＦ的模斑尺寸、ＬＤ的远场发散角成正比。最大失准容忍量是中心失准容忍量的Ｋ倍。     

Receiver analysis for synchronous coherent optical fiber transmission systems

A receiver sensitivity expression applicable for both PSK homodyne and heterodyne optical fiber transmission systems is derived taking account of polarization misalignment, reduced modulation depth, preamplifier thermal noise, power coupling ratio of the fiber coupler, local oscillator excess intensity noise, and reference phase errors. From a comparison of recent studies on system performance degradation due to laser phase noise a generalized expression relating beat linewidth to phase error variance for pilot carrier and Costas phase-locked-loop receivers is defined.     

低耦合损耗的光电混合光纤旋转连接器

设计了一种光电混合光纤旋转连接器,能实现相对旋转的光信号在较大对准误差范围内低损耗连接.旋转状态下的自聚焦透镜准直光纤输出的光信号,并由PIN光电探测器将其转换为电信号,冉由激光器根据电信号再生出原始光信号继续在光纤通讯系统中传输.该光电混合光纤旋转连接器在离轴偏移量至520μm或对准倾斜角至0.5°时的附加耦合损耗为0.3 dB,而采用双自聚焦透镜的光纤旋转连接器要获得小于3 dB的插入损耗,其离轴偏移或倾斜角度必须小于100 μm和0.10°相比之下,本文设计的光纤旋转连接器能降低系统对机械加上及装配精度的要求,具有较高的实用价值.     

4×4纵横交换微电机械系统光开关阵列

微电机械系统(MEMS)光开关是微电机系统技术与传统光学技术相结合的新型机械式光开关。采用纵横交换网络和通断型微镜实现4×4微电机械系统光开关阵列,利用球透镜单模光纤准直器作为微电机械系统光开关阵列的输入、输出端口。运用高斯光束耦合理论对光开关阵列插入损耗(IL)进行了理论计算,并对引起插入损耗的主要因素进行了分析。对于失调容限:输入与输出光纤准直器位置失调2μm,定位角度失调0.15°,微镜非垂直反射角度失调0.15°,制作了4×4微电机械系统光开关阵列,对其各个通道的插入损耗进行了实验测试,其中最大值为2.77dB。     

相干激光测风雷达环行器参量对测程的影响

为了提高激光测风雷达性能,采用数学建模的方法,基于环行器工作原理,分析了环行器出射光束质量,讨论了光束发散角对目标距离处激光峰值光强的影响,提出了环行器光束接收效率定义,研究了发射和接收光轴偏轴度对探测距离的影响。并搭建实验平台,取得远场光斑参量,验证了仿真结果。结果表明,随着出射光束发散角增大,相同作用距离处的相对峰值光强减小;雷达探测距离主要受偏轴角度的影响,mrad量级的偏角会使探测距离减小89.7%。因此,应合理增大光学天线准直倍率,并且设计的角度调节结构精度应优于0.1mrad量级。     

光纤微光开关光能传输特性分析

为了明确光纤光开关的光能传输特性,指导光纤光开关的设计、制造,利用光学设计软件ZEAMX建立了光纤光开关的仿真模型,分析了光纤对准误差对光纤耦合效率和输出光斑能量分布的影响.得出的结论是:纵向距离对耦合效率的影响不大,横向偏移和角度偏移对耦合效率的影响较大;光线经过一个玻璃和空气的界面时有3%的能量被反射;横向偏移和角度偏移将使输出光斑的能量分布不均匀、无规律.     

基于DFB激光器的楔形截顶光纤微透镜耦合结构

为了解决分布式反馈激光器的光发射次模块耦合封装中存在最大耦合效率局限的问题, 采用楔形截顶光纤微透镜代替分立式透镜的直接耦合的方法, 得到斜面倾角0.6rad、耦合距离60μm、半宽度15μm的楔形截顶光纤端面模型。在此基础上与分立式和直接耦合进行对比, 讨论了纵向、横向和角度偏移误差。结果表明, 纵向耦合距离在-21.45μm~56.79μm, 角向耦合角度在-8.3°~8.5°, 耦合效率始终大于70%;结构整体容忍度较高, 耦合效率达84.40%。该研究可为下一代分布式反馈激光器的次发射模块耦合封装器件提供新的解决方案。     

用于半导体激光器到单模光纤耦合的圆锥端微透镜设计

介绍了一种用于半导体激光器-单模光纤耦合的圆锥端半球透镜的耦合效率的理论计算.失配不存在时,耦合效率随着锥长的增加而减小.失配存在时耦合效率随轴向和角向失配的增大而减小.     

用于半导体激光器到单模光纤耦合的圆锥端微透镜设计

介绍了一种用于半导体激光器-单模光纤耦合的圆锥端半球透镜的耦合效率的理论计算.失配不存在时,耦合效率随着锥长的增加而减小.失配存在时耦合效率随轴向和角向失配的增大而减小     

基于热扩芯光纤的光纤准直器特性研究

为了提高光纤和光器件之间的耦合效率,设计了由热扩芯光纤和自聚焦透镜构成的新型热扩芯光纤准直器。理论上分析了热扩芯光纤准直器的基本结构参数与光学特性的关系以及由3种失配导致的耦合插入损耗。研究发现,热扩芯光纤准直器的耦合特性与自聚焦透镜的参数有关,热扩芯光纤准直器在轴向间距和角度偏差上的耦合失配容限明显优于普通光纤准直器,横向位移损耗则高于普通光纤准直器。采用模场半径为15.4μm的热扩芯光纤与自聚焦常数为0.295mm-1的自聚焦透镜制备了热扩芯光纤准直器,并对热扩芯光纤准直器因3种失配导致的耦合插入损耗进行了理论和实验比较,结果表明实验数据与理论吻合较好,说明所设计的热扩芯光纤准直器可用于长距离光耦合和旋转连接器件。     

光通信用自聚焦透镜耦合损耗的研究

针对单模光纤与自聚焦透镜（GRIN）的耦合,基于光学矩阵和高斯光学耦合损耗的理论,建立了计算耦合损耗的数学模型。利用这一模型分析了单模光纤与GRIN耦合时透镜的长度、离轴偏差及角度偏差等因素对耦合损耗的影响,得到了相应的规律性曲线。这对于自聚焦透镜系统成像理论的进一步研究和光纤通信耦合设计具有重要的意义。     

自聚焦棒透镜准直系统的装配误差引起的附加耦合损耗分析

一对１／４节距自聚焦棒透镜构成的准直系统通常存在三种装配误差：错位、间隔和倾斜,由此产生一定的附加耦合损耗。理论分析和数值计算结果表明,损耗与装配误差在小范围内近似呈平方递增关系,增幅与透镜聚焦参数有关。根据具体装配工艺选取合适的自聚焦棒透镜,能显著降低耦合损耗。     

Optical fiber tapers--A novel approach to self-aligned beam expansion and single-mode hardware

We investigate the performance characteristics of single-mode optical fiber tapers. These devices have a standard single-mode fiber geometry at one end and gradually increase in cross section so that the size of the core at the other end is comparable or greater to that of a multimode fiber. These tapers effectively expand the single-mode spot size and are envisioned as basic building blocks in a multitude of optical components. Analytical and experimental studies, atlambda = 0.63 mum, show that the dominant mode is preserved while traveling through the taper, from either direction. The excess coupling loss between two tapers is less than 0.1 dB. The sensitivity of the excess loss to lateral and axial displacements for two coupled tapered sections is greatly reduced compared to that between two single-mode fibers. The sensitivity to angular displacement is increased but is within practical limits. For example, for an excess loss of 0.5 dB, the maximum allowed lateral displacement is 3.1 μm for taper coupling, while only 0.73 μm is allowed in the case of fiber coupling. An axial displacement of 291 μm for taper coupling produces 0.5 dB loss while a displacement of only 16.5 μm produces a 0.5 dB loss for fiber coupling. For the same loss, angular displacements of 0.42° for the tapers and 1.77° for the fiber are allowed.     

Optical coupling characteristics of laser diodes to thermally diffused expanded core fiber coupling using an aspheric lens

A discussion is presented of the optical coupling characteristics of a 1.3 mu m laser diode to a thermally diffused expanded core (TEC) single-mode fiber coupling using an aspheric lens. The misalignment tolerance width for a 0.5 dB loss increment of the expanded core fiber was enlarged to 8.4 mu m from 1.9 mu m of a nonexpanded core fiber without a remarkable coupling-loss increase. The TEC fibers will make the LD module assembly easier, and reduce the assembly cost.<>     

激光成像系统中高耦合效率单模光纤耦合器设计

在三维激光成像系统中,其性能表现绝大部分决定于器件接收背反射光能幅度的大小,以及耦合器中空间光到光纤纤芯的光耦合效率的高低.为了增加耦合器中激光能量到纤芯内的耦合效率,提出了一种新型非球面透镜到锥形光纤头的耦合器的设计,得到了该耦合器中耦合效率的解析表达式.通过优化耦合透镜的倒相对孔径,对应波长为1 310 nm和1 ...     

New calculations for coupling laser diode to multimode fiber

A simple and useful method is presented for calculating characteristics of a laser diode to a multimode fiber coupling. Attenuation of higher order modes in multimode fiber is introduced into ray tracing. Maximum coupling efficiencies and misalignment tolerances of optical circuit components are computed for utilization of a relatively large spherical lens and combination of two relatively large spherical lenses. It is clarified that attenuation of higher order modes strongly affects both maximum coupling efficiency and misalignment tolerances. Agreement between theoretical and experimental coupling characteristics is greatly improved compared with the case for conventional ray tracing.     

塑料光纤耦合器的分析和研制

研究了一种新型的塑料光纤耦合器件.采用超声波熔接法制作塑料光纤耦合器,制作过程方便可行.分析了这种耦合器的长度和压缩厚度的变化对耦合比的影响,实验测试结果和计算机模拟分析基本一致.提出了降低工艺过程中的附加损耗的措施,实际制得的塑料光纤耦合器的耦合比和附加损耗能满足短距离通信上的使用要求.     

高精度透射式空间光学系统装调误差分析与动态控制

高分辨率对地观测对航天遥感器的成像质量提出了严格的要求,装框应力和偏心误差是影响大口径高精度透射式光学系统装调质量的重要因素。首先,在理论上分析了透镜装框应力的影响,实验测量了不同装调应力下的透镜面形,分析了装框应力对系统光学传递函数(MTF)的影响。然后,对光学元件的装调偏心误差进行了研究,测量了一个偏心系统的波前干涉图,分析了偏心导致的光学系统像差,仿真计算了不同透镜偏心误差对像差和MTF的影响。介绍了一种在偏心误差小量超差的情况下,利用中心偏测量仪、干涉仪的测量数据对光学系统进行实时仿真,动态控制装调质量的方法,并在实验上对预估结果进行了验证。结果表明:高精度透射式光学系统装调过程中光学偏心和应力导致的面形变化是影响光学系统质量的主要因素,偏心误差的影响大于应力的影响,不同透镜偏心误差对系统质量有着较大的差异且相互补偿。仿真预估方法能够在装调公差日益苛刻的情况下动态评定各误差间的相互影响与补偿,实时评价光学系统的质量,提高装调效率。     

Effect of acoustic birefringence on acoustooptic interaction in birefringent two-mode optical fibers

The acoustic birefringence in a highly birefringent (Hi-Bi) two-mode optical fiber is measured and shown to be about 0.8%. The birefringence is primarily caused by a cladding ellipticity in excess of 1%. The effect of the softer stress-inducing elements is small in comparison. The effects of misalignment of the acoustic and optical axes is studied in detail using both continuous-wave and pulsed acoustooptic interaction. In the Hi-Bi fiber, the misalignment is approximately 20/spl deg/. The acoustic birefringence and misalignment have a profound effect on the spectral characteristic of tunable acoustooptic notch- and passband filters, giving rise to double spectral peaks. The birefringence is not specific to Hi-Bi fibers. The same effect is demonstrated in a birefringent elliptic core fiber, and it should be expected also in standard telecom single-mode fibers. In tunable acoustooptic notch filters based on coupling to cladding modes in standard telecom fibers with ellipticity of the order of 1% the acoustic birefringence may cause double absorption peaks separated by more than 4 nm. It is also shown that acoustic birefringence provides guiding of the spatial orientation of the acoustic flexural waves, even if the fiber is twisted. This guiding effect eases the construction of acoustooptic components with long interaction length.