DFB光纤激光器

本文采用耦合波方程对DFB光纤激光器进行了理论的分析、计算,并在这些计算的基础上,成功研制出 DFB光纤激光器.     

楔形光纤排与半导体激光器耦合技术研究

首先从半导体激光器列阵的发光特性出发,利用楔形光纤排对大功率半导体激光器列阵光束进行耦合,最后得到一只含有19个纤芯,每个纤芯为200μm,数值孔径为0.12的大功率半导体激光器光纤耦合模块,输出功率为32.48W, 耦合效率为81.2%.     

光纤激光器透镜耦合系统的优化设计

准直一聚焦双透镜系统是光纤激光器中常用的一种泵浦耦合技术,但是对于大功率LD泵浦源尾纤输出的多模类高斯光束,难以解析表达其中高阶模式的透镜变换规律,根据此设计透镜耦合系统过程也很复杂。本文用几何光学的方法保证数值孔径的匹配,以类高斯光束光斑尺寸作为基模高斯光束束腰,用基模高斯光束传播规律来简化大功率光纤激光器透镜耦合系统的优化设计.最后给出了一个利用MAT-LAB优化工具函数设计双透镜聚焦耦合系统的实例。     

974nm半导体激光器的光纤耦合研究

根据半导体激光器和单模光纤模场分布特点,用模式耦合理论研究了单模光纤与半导体激光器的耦合,结果表明将光纤端面制作成楔形微透镜可以使光纤与半导体激光器的耦合满足模场匹配和相位匹配的要求。用遗传算法对楔形光纤微透镜参数进行优化,得到楔角为88°,柱透镜半径为3.44μm,耦合距离为6.13μm时耦合效率达到最佳值,用Zemax光学仿真软件对耦合模型进行仿真,得到耦合效率为88.9%,耦合好的模块经激光点焊及高低温环境测试后,得到最大耦合效率为81.36%。实验结果与仿真结果相差不大,耦合输出功率满足了作为光纤激光器种子源的功率要求。     

全金属化耦合封装的大功率半导体激光器模块

大功率半导体激光器模块对耦合封装工艺要求较高,耦合封装工艺直接影响模块的可靠性。采用金属化楔形微透镜光纤与大功率半导体激光器对准耦合,耦合效率达到87%;采用激光焊接定位的方式对大功率半导体激光器与楔形微透镜光纤进行耦合固定,实现了大功率半导体激光器模块的全金属化封装。通过环境考核试验证明,模块储存温度达到-60～120℃,能够满足许多特殊环境对半导体激光器模块的要求。     

微透镜提高光纤耦合效率

据我国台湾研究人员报道，把单模光纤的耦合端制成微透镜结构可以提高光纤与激光二极管的耦合效率。实验中，耦合端具有非对称椭圆锥微透镜（AECSM）的光纤与激光二极管（纵横比为5）的耦合效率最高达85％。而且他们制作AECSM结构的技术只需一步即可完成，可重复性好。     

与光纤阵列耦合的微透镜阵列设计与损耗分析

设计了2种不同冠高的圆形微透镜阵列,将平行光耦合进16路单模光纤阵列和多模光纤阵列。每种微透镜阵列均由16个直径为120pm的平凸微透镜排成一行组成,相邻微透镜间距为127μm。模拟其成像特性知,2种微透镜可以将平行光会聚成在其像平面直径分别为8．0μm和32．5μm的光斑。分析了微透镜与光纤存在横向、纵向和角向误差3种位置失配时的耦合损耗,并得出对耦合损耗影响最大的因素是角向误差,由此得出：在微透镜与光纤耦合对准过程中,要注意减小角向误差。     

用于激光到光纤最佳耦合的二元光学微透镜

采用位相平衡设计法设计了用于激光到光纤最佳耦合的二元光学微透镜，把二元光学微透镜看成是一种沿径向分布的特殊周期性位相结构，并用叠加积分法作了衍射分析，结果表明在不考虑光纤端面反射损耗的情况下，当用多模光纤接收时，设计的二元微透镜能使１００％的入射激光耦合至多模光纤，在光纤中激起的基模比例为９９．６０％；当用单模光纤接收时，设计的二元微透镜能使９９．９５％的入射激光耦合至单模光纤     

基于DFB激光器解调技术的光学电流互感器

针对交流电流的测量,提出了一种基于分布式反馈（DFH）激光器解调技术的光学电流互感器（0CT）。OCT的传感部分运用光纤Bragg光栅（FBG）和超磁致伸缩材料（GIⅢ①作为传感器探头,同时应用DFB激光器对FBG进行解凋,实现交流电流的测量。对于这种新型的OCT进行了理论分析和实验研究,实验测得系统传感灵敏度可达到1...     

Dependence of single-longitudinal-mode probability on DFB laser facet structure

The probability of single-longitudinal-mode (SLM) operation is calculated for three kinds of DFB facet structures. To obtain high SLM probability, a DFB laser with cleaved facets requires relatively large kL, but the introduction of asymmetry to facet reflectivity greatly relaxes the kL requirements.     

Coupling coefficient dependence on oscillation frequency stability of self-pulsating DFB laser diodes

Grating coupling strength effects in self-pulsating distributed feedback lasers were investigated. Choosing the coupling coefficient appropriately, improvements in the timing jitter as well as the injection locking sensitivity were observed experimentally. The results are attributed to a co-ordination of optical feedback strengths between dual lasing modes.     

Effect of Rayleigh backscattering from optical fibers on DFB laser wavelength

The effects of Rayleigh backscatter feedback from single-mode fibers on the spectral behavior of 1.5μm InGaAsP DFB lasers were measured. Rayleigh backscattering narrows the laser linewidth and induces frequency hops. The probability distribution for finding the laser at a particular frequency is reasonably approximated by a Gaussian distribution which has a width proportional to the laser-fiber coupling efficiency. Laser frequency excursions up to 1 GHz were observed and larger shifts are predicted to occur for stronger laser-fiber coupling. The experimental results agree well With a theory based on the Van der Pol oscillator model.     

Bidirectional optical subassembly with prealigned silicon microlens and laser diode

We have succeeded in developing a low-cost bidirectional optical subassembly chip using a silicon microlens for fiber-to-the-home application. The main optical elements of the bidirectional function were automatically aligned and integrated on a silicon optical bench. The cost of subassembly was markedly lowered both by reducing the part number and simplifying the assembly process. The prototype bidirectional optical component was successfully fabricated on the basis of the proposed chip. A receiver minimum sensitivity of -28.5 dBm was experimentally demonstrated even at 75 /spl deg/C.     

基于1665 nm激光器测量甲烷气体浓度的研究

介绍了一种以1665 nm分布反馈(DFB)激光器为光源,使用双光路差分吸收光谱技术(DAS)测量甲烷浓度的检测系统。双光路差分吸收光谱技术能有效抑制由于光源光强变化、探测器零点漂移等因素所引起的测量的不准确。文中对这种检测方法进行了理论和实验分析,系统的最小探测浓度为100×10-6,响应时间约为14 s。     

High-efficiency operation of phase-adjusted DFB laser by asymmetric structure

Differential efficiency has been increased by 50% in a phase-adjusted DFB laser by the introduction of an asymmetric structure. The problem of mode degeneracy in DFB lasers has been resolved without penalty on efficiency and output power.     

基于像散曲面微透镜的半导体激光准直研究

为了实现半导体激光器的光束准直,分析了半导体激光器光束沿快、慢轴方向的准直原理。采用单个半导体激光器作为被准直单元,提出了基于像散曲面微透镜的半导体激光器光束准直方法。讨论了半导体激光器填充因子对像散曲面微透镜准直性能的影响。对填充因子0.5的半导体激光器进行模拟验证。准直后,快轴方向剩余发散角约为0.34,慢轴方向剩余发散角约为2.69。结果表明,像散曲面微透镜不但可以对高填充因子的半导体激光器光束进行准直,而且准直后出射光斑面积小。该研究为高功率半导体激光器堆栈光束的准直提供了可行性方案。     

Multiwavelength DFB laser array transmitters for ONTCreconfigurable optical network testbed

We discuss the design, fabrication, and performance of experimental multiwavelength laser array transmitters that have been used in the reconfigurable optical network testbed for the Optical Network Technology Consortium (ONTC). The experimental four-node multiwavelength network testbed is SONET/ATM compatible. It has employed multiwavelength DFB laser arrays with 4 nm wavelength spacing for the first time. The testbed has demonstrated that multiwavelength DFB laser arrays are indeed practical and reproducible. For the DFB laser arrays used in such a network the precise wavelength spacing in the array and the absolute wavelength control are the most challenging tasks. We have obtained wavelength accuracy better than ±0.35 nm for all lasers, with some registered to better than ±0.2 nm. We have also studied the array yield of our devices and used wavelength redundancy to improve the array yield. Coupling efficiencies between -2.1 to -4.5 dB for each wavelength channel have been obtained. It is achieved by using specially designed lensed fiber arrays placed on a silicon V-grooved substrate to exactly match the laser spacing. The transmitter consisted of a multichip module containing a DFB laser array, an eight-channel driver array based on GaAs IC's, and associated RF circuitry     

Effect of laser chirp on optical systems?initial tests using a 1480 nm DFB laser

Initial assessment of the effect of laser ?chirp? on optical systems is described. Measurements of the wavelength shift and its effect on the received pulse after 4 km and 80 km of dispersive fibre are presented. The results are in good agreement with simple modelling, which predicts no penalty for this system Further tests are needed to determine whether this behaviour is typical.